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  • 1995-1999  (1,814)
  • 1955-1959  (3,070)
  • 1925-1929  (4,111)
  • 1890-1899  (8,112)
  • Inorganic Chemistry  (17,066)
  • genetic engineering
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  • 1
    Electronic Resource
    Electronic Resource
    Keeping Up with the Cloneses -- Issues in Human Cloning (1999)
    Springer
    The journal of ethics 3 (1999), S. 51-71 
    Details
    ISSN: 1572-8609
    Keywords: biotechnology ; cloning ; ethics of biotechnology ; ethics of cloning ; ethics of human cloning ; ethics for reproductive technology ; genetic engineering ; human cloning ; religious ethics ; reproductive technology ; secular ethics ; social ethics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Philosophy
    Notes: Abstract The advent of cloning animals has created a maelstrom of social concern about the “ethical issues” associated with the possibility of cloning humans. When the “ethical concerns” are clearly examined, however, many of them turn out to be less matters of rational ethics than knee-jerk emotion, religious bias, or fear of that which is not understood. Three categories of real and spurious ethical concerns are presented and discussed: 1) that cloning is intrinsically wrong, 2) that cloning must lead to bad consequences, and 3) that cloning harms the organism generated. The need for a rational ethical framework for discussing biotechnological advances is presented and defended.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009775715165
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  • 2
    Electronic Resource
    Electronic Resource
    Genetic engineering of shikonin biosynthesis hairy root cultures of Lithospermum erythrorhizon transformed with the bacterial ubiC gene (1999)
    Springer
    Plant molecular biology 39 (1999), S. 683-693 
    Details
    ISSN: 1573-5028
    Keywords: genetic engineering ; 4-hydroxybenzoic acid glucoside ; Lithospermum erythrorhizon ; menisdaurin ; shikonin ; ubiC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The biosynthetic pathway to 4-hydroxybenzoate (4HB), a precursor of the naphthoquinone pigment shikonin, was modified in Lithospermum erythrorhizon hairy root cultures by introduction of the bacterial gene ubiC. This gene of Escherichia coli encodes chorismate pyruvate-lyase (CPL), an enzyme that converts chorismate into 4HB and is not normally present in plants. The ubiC gene was fused to the sequence for a chloroplast transit peptide and placed under control of a constitutive plant promoter. This construct was introduced into L. erythrorhizon by Agrobacterium rhizogenes-mediated transformation. The resulting hairy root cultures showed high CPL activity. 4HB produced by the CPL reaction was utilized for shikonin biosynthesis, as shown by in vivo inhibition of the native pathway to 4HB with 2-aminoindan-2-phosphonic acid (AIP), an inhibitor of phenylalanine ammonia-lyase. A feeding experiment with [1,7-13C2]shikimate showed that in the absence of AIP the artificially introduced CPL reaction contributed ca. 20% of the overall 4HB biosynthesis in the transgenic cultures. ubiC transformation did not lead to a statistically significant increase of shikonin formation, but to a 5-fold increase of the accumulation of menisdaurin, a nitrile glucoside which is presumably related to aromatic amino acid metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006185806390
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  • 3
    Electronic Resource
    Electronic Resource
    Questions about the complexity of chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase (1999)
    Springer
    Photosynthesis research 60 (1999), S. 29-42 
    Details
    ISSN: 1573-5079
    Keywords: enzyme catalysis ; evolution ; genetic engineering ; photosynthesis ; protein assembly ; protein degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) has played a central role in our understanding of chloroplast biogenesis and photosynthesis. In particular, its catalysis of the rate-limiting step of CO2 fixation, and the mutual competition of CO2 and O2 at the active site, makes Rubisco a prime focus for genetically engineering an increase in photosynthetic productivity. Although it remains difficult to manipulate the chloroplast-encoded large subunit and nuclear-encoded small subunit of crop plants, much has been learned about the structure/function relationships of Rubisco by expressing prokaryotic genes in Escherichia coli or by exploiting classical genetics and chloroplast transformation of the green alga Chlamydomonas reinhardtii. However, the complexity of chloroplast Rubisco in land plants cannot be completely addressed with the existing model organisms. Two subunits encoded in different genetic compartments have coevolved in the formation of the Rubisco holoenzyme, but the function of the small subunit remains largely unknown. The subunits are posttranslationally modified, assembled via a complex process, and degraded in regulated ways. There is also a second chloroplast protein, Rubisco activase, that is responsible for removing inhibitory molecules from the large-subunit active site. Many of these complex interactions and processes display species specificity. This means that attempts to engineer or discover a better Rubisco may be futile if one cannot transfer the better enzyme to a compatible host. We must frame the questions that address this problem of chloroplast-Rubisco complexity. We must work harder to find the answers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006240202051
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  • 4
    Electronic Resource
    Electronic Resource
    Wounding by bombardment yields highly efficient Agrobacterium-mediated transformation of carnation (Dianthus caryophyllus L.) (1999)
    Springer
    Molecular breeding 5 (1999), S. 367-375 
    Details
    ISSN: 1572-9788
    Keywords: transgenic carnation ; genetic engineering ; microprojectile bombardment ; stable transformation ; kanamycin selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Highly efficient Agrobacterium-mediated transformation of carnation (Dianthus caryophyllus L.) was obtained by first wounding stem explants via microprojectile bombardment. When this was followed by cocultivation with disarmed Agrobacterium in the dark, the transformation frequency-based on transient GUS expression-increased to over 10-fold that of explants wounded by other means and cocultivated under constant light. Two cycles of regeneration/selection on kanamycin were employed to generate stably transformed carnation plants and eliminate chimeras: first, plantlets were regenerated from inoculated stem explants and then leaves from these plantlets were used to generate transgenes in a second selection cycle of adventitious shoot regeneration. Agrobacterium strain AGLO, carrying the binary vector pCGN7001 containing uidA and nptII genes, was used in the stable transformation experiments. The combination of wounding via bombardment, cocultivation in the dark and two cycles of kanamycin selection yielded an overall transformation efficiency of 1–2 transgenes per 10 stem explants for the three carnation varieties analyzed. Histochemical and molecular analyses of marker genes in T0 and T1 generations confirmed the transgenic nature of the selected plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009671131200
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  • 5
    Electronic Resource
    Electronic Resource
    Genetic Engineering of Protein-Based Polymers: Potential in Controlled Drug Delivery (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 813-815 
    Details
    ISSN: 1573-904X
    Keywords: genetic engineering ; polymers ; drug delivery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011999810298
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  • 6
    Electronic Resource
    Electronic Resource
    Review: Application of biotechnology to forestry – molecular biology of conifers (1998)
    Springer
    World journal of microbiology and biotechnology 14 (1998), S. 321-330 
    Details
    ISSN: 1573-0972
    Keywords: Conifer transformation ; forestry ; genetic engineering ; plantation forestry ; tree improvement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Genetic improvement in plantation forestry relies significantly on conventional breeding techniques which have been used extensively to improve various characteristics in forest trees such as growth and form, volume yield, resistance to pathogens and quality of the end product. This review concentrates on molecular techniques which have been used successfully in agriculture and which have more recently become available to improve further characteristics of forest trees and introduce new traits which are currently not available in the breeding population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008848824626
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  • 7
    Electronic Resource
    Electronic Resource
    Crystal structures and properties of de novo circularly permuted 1,3-1,4-β-glucanases (1998)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 30 (1998), S. 155-167 
    Details
    ISSN: 0887-3585
    Keywords: X-ray diffraction ; protein folding ; genetic engineering ; circular permutation ; 1,3-1,4-β-glucanase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The 1,3-1,4-β-glucanases from Bacillus macerans and Bacillus licheniformis, as well as related hybrid enzymes, are stable proteins comprised of one compact jellyroll domain. Their structures are studied in an effort to reveal the degree of redundancy to which the three-dimensional structure of protein domains is encoded by the amino acid sequence. For the hybrid 1,3-1,4-β-glucanase H(A16-M), it could be shown recently that a circular permutation of the sequence giving rise to the variant cpA16M-59 is compatible with wildtype-like enzymatic activity and tertiary structure (Hahn et al., Proc. Natl. Acad. Sci. USA 91:10417-10421, 1994). Since the circular permutation yielding cpA16M-59 mimicks that found in the homologous enzyme from Fibrobacter succinogenes, the question arose whether de novo circular permutations, not guided by molecular evolution of the 1,3-1,4-β-glucanases, could also produce proteins with native-like fold. The circularly permuted variants cpA16M-84, cpA16M-127, and cpA16M-154 were generated by PCR mutagenesis of the gene encoding H(A16-M), synthesized in Escherichia coli and shown to be active in β-glucan hydrolysis. CpA16M-84 and cpA16M-127 were crystallized in space groups P21 and P1, respectively, and their crystal structures were determined at 1.80 and 2.07 Å resolution. In both proteins the main parts of the β-sheet structure remain unaffected by the circular permutation as is evident from a root-mean-square deviation of main chain atoms from the reference structure within the experimental error. The only major structural perturbation occurs near the novel chain termini in a surface loop of cpA16M-84, which becomes destabilized and rearranged. The results of this study are interpreted to show that: (1) several circular permutations in the compact jellyroll domain of the 1,3-1,4-β-glucanases are tolerated without radical change of enzymatic activity or tertiary structure, (2) the three-dimensional structures of simple domains are encoded by the amino acid sequence with sufficient redundancy to tolerate a change in the sequential order of secondary structure elements along the sequence, and (3) the native N-terminal region is not needed to guide the folding polypeptide chain toward its native conformation. Proteins 30:155-167, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Genetic engineering approaches to enzyme design and mechanism (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 536-539 
    Details
    ISSN: 0894-3230
    Keywords: enzyme design ; enzyme mechanism ; genetic engineering ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Aspartate aminotransferase (AATase) and aminocyclopropane carboxylate synthase (ACC synthase) are pyridoxal phosphate (PLP)-dependent enzymes whose common junction of mechanistic divergence is after the formation of a Cα carbanion from the amino acid substrate bound to PLP as a Schiff base (aldimine). AATase catalyzes the reversible interconversion of α-amino acids and α-keto acids, while ACC synthase effects the irreversible decomposition of S-adenosylmethionine (SAM) to 1-aminocyclopropane-1-carboxylate (ACC) and 5′-methylthioadenosine (MTA). ACC is subsequently converted to ethylene, the plant ripening and senescence hormone, by ACC oxidase, the next enzyme in the pathway. AATase and ACC synthase exhibit many similar phenomenological characteristics that result from different detailed mechanistic origins. The kcat/KM versus pH profiles for both enzymes are similar (AATase, acidic pKa = 6.9, basic pKa = 9.6; ACC synthase, acidic pKa = 7.5, basic pKa = 8.9); however the acidic pKa of AATase reflects the ionization of an enzyme proton from the internal Schiff base, and the basic one is that of the α-amino group of the substrate, while the opposite situation obtains for ACC synthase, i.e. the apparent pKa of 7.4 is due to the α-amino group of SAM, whereas that of 9 reflects the Schiff base pKa. The mechanistic imperative underlying this reversal is dictated by the reaction mechanism and the low pKa of the α-amino group of SAM. The low pKa of SAM requires that the enzyme pKa be moved upward in order to have sufficient quantities of the reacting species at neutral pH. It is shown by viscosity variation experiments with wild-type and active site mutant controls of both enzymes that the reaction of SAM with ACC synthase is 100% diffusion controlled (kcat/KM = 1.2 × 106 l mol-1 s-1) while the corresponding reaction for the combination of L-aspartate with AATase is insensitive to viscosity, and is therefore chemically not diffusion limited. Tyr225 (AATase) or Tyr233 (ACC synthase) forms a hydrogen bond with the PLP in both enzymes, but that formed with the former enzyme is stronger and accounts for the lower pKa of the Schiff base. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 7 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Stable Production of Human Insulin-like Growth Factor 1 (IGF-1) in the Milk of Hemi- and Homozygous Transgenic Rabbits Over Several Generations (1998)
    Springer
    Transgenic research 7 (1998), S. 437-447 
    Details
    ISSN: 1573-9368
    Keywords: bioreactor ; gene farming ; genetic engineering ; mammary gland ; milk composition ; recombinant protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One transgenic rabbit line was generated carrying a fusion gene consisting of the cDNA for human IGF-1 fused to a mammary gland specific expression cassette derived from bovine alpha-S1-casein sequences. Transgene expression was shown to be strictly tissue and lactation period specific. The transgenic rabbit line was bred for six generations. All transgenic animals showed stable production of biologically active IGF-1 over the generations and no apparent effect on the physiological or reproductive performance was observed. The absence of adverse effects on homozygous transgenic rabbits suggested the absence of insertional mutagenesis. Eight hemizygous transgenic offspring analysed produced on average 363 ± 12μg/ml (ranging from 223 ± 61 to 484 ± 39 μg/ml) mature human IGF-1 in their milk, whereas three homozygous animals produced on average 543 ± 41 μg/ml (ranging from 360 ± 15 to 678 ± 80 μg/ml). Homozygous huIGF-1 females clearly showed a significantly increased production performance of the recombinant protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008831028620
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  • 10
    Electronic Resource
    Electronic Resource
    Metabolic engineering of rice leading to biosynthesis of glycinebetaine and tolerance to salt and cold (1998)
    Springer
    Plant molecular biology 38 (1998), S. 1011-1019 
    Details
    ISSN: 1573-5028
    Keywords: choline oxidase ; genetic engineering ; glycinebetaine ; low-temperature tolerance ; salt tolerance ; transgenic rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genetically engineered rice (Oryza sativa L.) with the ability to synthesize glycinebetaine was established by introducing the codA gene for choline oxidase from the soil bacterium Arthrobacter globiformis. Levels of glycinebetaine were as high as 1 and 5 μmol per gram fresh weight of leaves in two types of transgenic plant in which choline oxidase was targeted to the chloroplasts (ChlCOD plants) and to the cytosol (CytCOD plants), respectively. Although treatment with 0.15 m NaCl inhibited the growth of both wild-type and transgenic plants, the transgenic plants began to grow again at the normal rate after a significantly less time than the wild-type plants after elimination of the salt stress. Inactivation of photosynthesis, used as a measure of cellular damage, indicated that ChlCOD plants were more tolerant than CytCOD plants to photoinhibition under salt stress and low-temperature stress. These results indicated that the subcellular compartmentalization of the biosynthesis of glycinebetaine was a critical element in the efficient enhancement of tolerance to stress in the engineered plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006095015717
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  • 11
    Electronic Resource
    Electronic Resource
    Expression of a chitinase transgene in rose (Rosa hybrida L.) reduces development of blackspot disease (Diplocarpon rosae Wolf) (1998)
    Springer
    Molecular breeding 4 (1998), S. 187-194 
    Details
    ISSN: 1572-9788
    Keywords: chitinase ; Diplocarpon rosae ; disease resistance ; genetic engineering ; Rosa hybrida L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Blackspot, caused by the Ascomycete fungus Diplocarpon rosae, is the most widespread and pernicious disease of cultivated roses. While some species of rose possess resistance to D. rosae, none of the modern-day rose cultivars are fully resistant to the pathogen. In the current study, Biolistic gene delivery was used to introduce a rice gene, encoding a basic (Class I), chitinase into embryogenic callus of the blackspot-susceptible rose (Rosa hybrida L.) cv. Glad Tidings. The plasmid used for transformation carried the neomycin phosphotransferase (nptII) gene facilitating the selection and regeneration of transgenic plants on medium containing 250 mg/l kanamycin. Southern analysis confirmed integration of 2–6 copies of the chitinase gene into the rose genome; gene expression was confirmed by enzyme assay. Bioassays demonstrated that expression of the chitinase transgene reduced the severity of blackspot development by 13–43%. This degree of resistance to the pathogen correlated with the level of chitinase expression in the transgenic rose plants. The introduction of disease defence genes into rose provides a method of producing blackspot-resistant rose cultivars sought by breeders and growers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009642707505
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  • 12
    Electronic Resource
    Electronic Resource
    How will bioinformatics influence metabolic engineering? (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 58 (1998), S. 162-169 
    Details
    ISSN: 0006-3592
    Keywords: bioinformatics ; metabolic engineering ; genetic engineering ; mathematical analysis ; stoichiometry ; enzyme kinetics ; modal analysis ; genetic circuits ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ten microbial genomes have been fully sequenced to date, and the sequencing of many more genomes is expected to be completed before the end of the century. The assignment of function to open reading frames (ORFs) is progressing, and for some genomes over 70% of functional assignments have been made. The majority of the assigned ORFs relate to metabolic functions. Thus, the complete genetic and biochemical functions of a number of microbial cells may be soon available. From a metabolic engineering standpoint, these developments open a new realm of possibilities. Metabolic analysis and engineering strategies can now be built on a sound genomic basis. An important question that now arises; how should these tasks be approached? Flux-balance analysis (FBA) has the potential to play an important role. It is based on the fundamental principle of mass conservation. It requires only the stoichiometric matrix, the metabolic demands, and some strain specific parameters. Importantly, no enzymatic kinetic data is required. In this article, we show how the genomically defined microbial metabolic genotypes can be analyzed by FBA. Fundamental concepts of metabolic genotype, metabolic phenotype, metabolic redundancy and robustness are defined and examples of their use given. We discuss the advantage of this approach, and how FBA is expected to find uses in the near future. FBA is likely to become an important analysis tool for genomically based approaches to metabolic engineering, strain design, and development. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:162-169, 1998.
    Additional Material: 4 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    Genetic engineering of Serratia marcescens with bacterial hemoglobin gene: Effects on growth, oxygen utilization, and cell size (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 477-483 
    Details
    ISSN: 0006-3592
    Keywords: Vitreoscilla hemoglobin ; bacterial hemoglobin ; Serratia marcescens ; genetic engineering ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The bacterial hemoglobin from Vitreoscilla has been shown to increase growth yield and yield of genetically engineered product in Escherichia coli. To test the generality of this phenomenon, the approximately 560-bp bacterial (Vitreoscilla) hemoglobin gene (vgb) (including the native promoter), cloned into the vector pUC8 in two constructs containing about 1650 and 850 bp, respectively, of Vitreoscilla DNA downstream of vgb, was transformed into Serratia marcescens. After several transfers of the transformants on selective media, both plasmids became stable in this host and the resulting strains produced hemoglobin. Both transformants were compared, regarding growth in liquid Luria-Bertani (LB) medium, with untransformed S. marcescens and S. marcescens transformed with pUC8. The vgb-bearing strains had about 5 times lower maximum viable cell numbers than the strains without hemoglobin, but the former also had late log or early stationary phase cells that were 5-10 times larger than those of the latter. Further, on a dry cell mass basis the presence of vgb inhibited cell growth in liquid media. In contrast, growth of the vgb-bearing strains on LB plates based on cell mass (determined from colony size) was markedly enhanced compared with that of the pUC8 transformant. Respiration of the vgb-bearing strains was lower than that of the strains without vgb on a cell mass basis. These results show that the presence of vgb can have idiosyncratic effects and is not always an aid to cell growth so that its use for genetic engineering must be tested on a case by case basis. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 477-483, 1998.
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  • 14
    Electronic Resource
    Electronic Resource
    Genetically engineered syntheses of tandem repetitive polypeptides consisting of glycine-rich sequence of spider dragline silk (1998)
    New York : Wiley-Blackwell
    Biopolymers 45 (1998), S. 269-279 
    Details
    ISSN: 0006-3525
    Keywords: spider dragline silk ; genetic engineering ; glycine-rich sequence ; β-sheet structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We described genetically engineered syntheses of tandem repetitive polypeptides consisting of glycine-rich sequence, GlyLeuGlyGlyGlnGlyGlyGlyAlaGlyGlnGlyGlyTyrGly, designated SCAP(1), in spidroin I of spider dragline silk from Nephila clavipes and the secondary conformational analyses in the solid state by Fourier transform ir measurements. The polypeptides composed of 4, 5, 6, 7, 11, 12, or 13 repeats of SCAP(1) were expressed in Escherichia coli, purified by nickel chelate affinity chromatography, and then cleaved with cyanogen bromide to release N- and C-terminal extensions. Typical yields were from 1.2 to 5.2 mg of lyophilized uncleaved polypeptides per liter of fermentation medium at an absorbance of 2.0 at 600 nm, and the production levels increased with decreasing the molecular weight of the expressed polypeptides. The lyophilized powder of cleaved SCAP(13) adopted the random coil, whereas the cast film from formic acid formed the β-sheet structure. The conformational results might indicate that the glycine-rich sequence formed β-sheet structure in spidroin I. Cleaved SCAP(13) started to decompose under nitrogen at ca. 230°C, which was in agreement with the decomposition temperature of the spider dragline silk from N. clavipes. © 1998 John Wiley & Sons, Inc. Biopoly 45: 269-279, 1998
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  • 15
    Electronic Resource
    Electronic Resource
    Engineered cell lines for insulin replacement in diabetes: current status and future prospects (1997)
    Springer
    Diabetologia 40 (1997), S. S42 
    Details
    ISSN: 1432-0428
    Keywords: Keywords Insulin ; genetic engineering ; cell lines ; transplantation ; molecular biology.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The recently completed diabetes complications and control trial has highlighted the need for improvement of insulin delivery systems for treatment of insulin-dependent diabetes mellitus. Despite steady improvement in methods for islet and whole pancreas transplantation over the past three decades, the broad-scale applicability of these approaches remains uncertain due in part to the difficulty and expense associated with procurement of functional tissue. To address this concern, we and others have been using the tools of molecular biology to develop cell lines with regulated insulin secretion that might serve as a surrogate for primary islets or pancreas tissue in transplantation therapy. This article seeks to provide a brief summary of the current status of this growing field, with a particular emphasis on progress in producing cell lines with appropriate glucose-stimulated insulin secretion. [Diabetologia (1997) 40: S 42–S 47]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001250051398
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  • 16
    Electronic Resource
    Electronic Resource
    Genetic engineering of bacteria and their potential for Hg2+ bioremediation (1997)
    Springer
    Biodegradation 8 (1997), S. 97-103 
    Details
    ISSN: 1572-9729
    Keywords: Escherichia coli ; genetic engineering ; mercury bioaccumulation ; mercury transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ion exchange or biosorptive processes for metalremoval generally lack specificity in metal bindingand are sensitive to ambient conditions, e.g. pH,ionic strength and the presence of metal chelators. Inthis study, cells of a genetically engineered Escherichia coli strain, JM109, which expressesmetallothionein and a Hg2+ transport system afterinduction were evaluated for their selectivity forHg2+ accumulation in the presence of sodium,magnesium, or cadmium ions and their sensitivity to pHor the presence of metal chelators during Hg2+bioaccumulation. The genetically engineered E.coli cells in suspension accumulated Hg2+effectively at low concentrations (0-20 µM) overa broad range of pH (3 to 11). The presence of 400 mMsodium chloride, 200 mM magnesium chloride, or100 µM cadmium ions did not have a significanteffect on the bioaccumulation of 5 µm Hg2+,indicating that this process is not sensitive to highionic strength and is highly selective against sodium,magnesium, or cadmium ions. Metal chelators usuallyinterfere with ion exchange or biosorptive processes.However, two common metal chelators, EDTA and citrate,had no significant effect on Hg2+ bioaccumulationby the genetically engineered strain. These resultssuggest that this E. coli strain could be usedfor selective removal of Hg2+ from waste water orfrom contaminated solutions which are resistant tocommon treatments. A second potential applicationwould be to remove Hg2+ from Hg2+-contaminated soil, sediment, or particulates bywashing them with a Hg2+ chelator andregenerating the chelator by passing the solutionthrough a reactor containing the strain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008233704719
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  • 17
    Electronic Resource
    Electronic Resource
    Nif gene transfer and expression in chloroplasts: Prospects and problems (1997)
    Springer
    Plant and soil 194 (1997), S. 193-203 
    Details
    ISSN: 1573-5036
    Keywords: chloroplast ; genetic engineering ; nif genes ; nitrogenase ; plant transformation ; plastid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The engineering of plants capable of fixing their own nitrogen is an extremely complex task, requiring the co-ordinated and regulated expression of 16 nif genes in an appropriate cellular location. We suggest that plastids may provide a favourable environment for nif gene expression provided that the nitrogenase enzyme can be protected from oxygen damage. Using the non-heterocystous cyanobacteria as a model, we argue that photosynthesis could be temporally separated from nitrogen fixation in chloroplasts by restricting nitrogenase synthesis to the dark period. We report preliminary data on the introduction and expression of one of nitrogenase components, the Fe protein, in transgenic tobacco and Chlamydomonas reinhardtii. Finally we discuss potential avenues for further research in this area and the prospects for achieving the ultimate goal of expressing active nitrogenase in cereal crops such as rice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004296703638
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  • 18
    Electronic Resource
    Electronic Resource
    Plant nutrition in the 20th and perspectives for the 21st century (1997)
    Springer
    Plant and soil 196 (1997), S. 163-174 
    Details
    ISSN: 1573-5036
    Keywords: fertilizers ; food production ; genetic engineering ; macronutrients ; micronutrients ; nutrient absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper briefly presents the knowledge of plant nutrition in 1900 and its expansion since then in two areas - the discovery of the micronutrients and the absorption of nutrients from soils. Application of macro- and micronutrient fertilizers has contributed substantially to the huge increase in world food production experienced this century. In developed countries, excessive fertilizer use has led to serious problems of nutrient pollution; here, plant nutritionists will be concerned with monitoring nutrient status of crops and soils to maintain crop production with minimum loss of nutrients to the environment, and development of cultivars with high nutrient efficiency in soils with luxury supplies of nutrients. In many developing countries, soil infertility limits productivity; here, plant nutritional research can raise productivity by diagnosis of nutrient deficiencies and toxicities of crops on previously unfertilized soils, their correction with minimal fertilizer and treatment costs, and development of cultivars with high nutrient efficiency in deficient soils and high tolerance of natural toxicities. The pre-occupation of developed countries with pollution is blinding them to the urgent needs of developing countries for fertilizers and fertilizer research to increase crop production ha-1 as an alternative to clearing more land.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004208621263
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  • 19
    Electronic Resource
    Electronic Resource
    Mitochondria transfer into mouse ova by microinjection (1997)
    Springer
    Transgenic research 6 (1997), S. 379-383 
    Details
    ISSN: 1573-9368
    Keywords: genetic engineering ; heteroplasmy ; mouse ; mitochondria ; mitochondria transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method for mitochondria isolation and interspecific transfer of mitochondria was developed in mice. Mitochondria were isolated from Mus spretus liver samples for microinjection into fertilized ova obtained from superovulated M. musculus domesticus females. Electron microscopic observations of mitochondria preparations used for microinjection demonstrated intact mitochondrial vesicles with little microsomal contamination. Species-specific nested PCR primers complementary to sequence differences in the mitochondrial DNA D-loop region revealed high rates of successful transfer of foreign mitochondria after isolation and injection into zygotes cultured through the blastocyst stage of embryonic development. Of 217 zygotes, 67 survived mitochondria injection and 23 out of 37 zygotes developed were at the blastocyst-stage of embryonic development after 4.5 days of in vitro culture. All 23 of these blastocysts contained detectable levels of foreign mitochondria. These results represent an initial step in developing a model system to study mitochondrial dynamics and development of therapeutic strategies for human metabolic diseases affected by aberrations in mitochondrial function or mutation
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018431316831
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  • 20
    Electronic Resource
    Electronic Resource
    Rice transformation: bombardment (1997)
    Springer
    Plant molecular biology 35 (1997), S. 197-203 
    Details
    ISSN: 1573-5028
    Keywords: genetic engineering ; particle bombardment ; plant biotechnology ; transgenic rice ; Oryza sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bombardment-based methodology is responsible for the effective genetic manipulation of major cereals including rice. Many groups reported significant advances on various aspects of rice molecular biology and genetic engineering using procedures based on bombardment technology. Molecular and genetic characterization of large numbers of these plants (more than 500 independent transgenic plants) provided information on structure, expression and stability of integrated DNA through multiple generations. Such evaluations were carried out in the greenhouse and in the field. Stability of expression was found to be dependent on the nature of the promoter and the transgene, and in specific cases on gene copy number. Direct DNA transfer utilizing particle bombardment for the delivery of foreign DNA into rice tissue results in the recovery of large numbers of independently derived transgenic plants in a variety-independent fashion. Gene copy number, level and stability of expression of transgenes can be compared to other DNA delivery methods, direct or indirect, including Agrobacterium-mediated gene transfer. In this paper, the technology is summarized and discussed in terms of present and future applications, including field trials and potential commercialization of transgenic rice expressing a number of genes of agronomic interest such as pest and herbicide resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005791230345
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  • 21
    Electronic Resource
    Electronic Resource
    Is there any possibility of detecting the use of genetic engineering in processed foods? (1997)
    Springer
    European journal of nutrition 36 (1997), S. 155-160 
    Details
    ISSN: 1436-6215
    Keywords: Detection method ; genetic engineering ; polymerase chain reaction ; processed food ; Gentechnik ; Nachweisverfahren ; Polymerasekettenreaktion ; verarbeitete Lebensmittel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Bier, Sojaöl, verarbeitete Tomaten- (Ketchup, Mark, Pizzatomaten, Schältomaten, Suppe) und Kartoffelprodukte (Pommes frites, Chips, Püree, Mehl, Stärke, Bratkartoffeln) sowie ein Enzympräparat (Natuphos) wurden mittels PCR daraufhin untersucht, ob ein Nachweis des Einsatzes der Gentechnik bei ihrer Herstellung möglich ist. PCR-fähige DNA ließ sich aus Pizzatomaten, Schältomaten, Pommes frites, Bratkartoffeln, Kartoffelmehl und Kartoffelchips isolieren, so daß der Nachweis des Einsatzes der Gentechnik bei deren Herstellung möglich wird. Bestimmte Biere (Pils, Export, Nutfield lyte), Sojaöl, Tomatensuppe, Kartoffelstärke, Kartoffelpüree und Natuphos entziehen sich einem solchen Nachweis, da die PCR-Analyse keine Hinweise auf das Vorliegen von DNA in diesen Produkten ergab. Daß das durchgeführte Nachweisverfahren grundsätzlich in der Lage ist, geringe Mengen an DNA auch in diesen Produkten spezifisch nachzuweisen, wurde nach Zugabe vonEscherichia coli DNA bestätigt.
    Notes: Summary To elucidate if there is any possibility to identify highly processed foods as produced through genetic engineering, beer, soya bean oil, processed tomato (ketch-up, paste, pizza tomatoes, peeled tomatoes, soup) and potato (french fries, crisps, mashed potatoes, flour, starch, fried potatoes) products as well as an enzyme preparation (Natuphos) were investigated by PCR. In pizza tomatoes, peeled tomatoes, french fries, fried potatoes, potato flour and potato crisps DNA suitable for PCR was found. Therefore, it is possible to identify these products as produced through genetic engineering. Such an identification is impossible in certain beers (pilsener, export, Nutfield lyte), soya bean oil, tomato soup, potato starch, mashed potatoes and Natuphos since PCR-analysis gave no indication of the presence of DNA in these products. As it was shown by addingEscherichia coli DNA the used method is, in principle, capable of detecting specifically small amounts of DNA in such products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01611394
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  • 22
    Electronic Resource
    Electronic Resource
    Asymmetric Catalysis, 105Part 104: Ref.. Stereoselective Hydrogenation of Folic Acid with Immobilized Optically Active Rhodium(I)/Diphosphane Catalysts (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 55-62 
    Details
    ISSN: 0009-2940
    Keywords: Diastereoselective hydrogenation ; Folic acid ; Immobilized optically active rhodium(I)/diphosphane catalysts ; Leucovorin ; HPLC analysis of 5-formyltetrahydrofolic acid derivatives ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For the hydrogenation of the C=N bonds in the pyrazine ring of the vitamin folic acid (1) optically active rhodium(I)/diphosphane complexes immobilized on supports such as silica gel or Al2O3 were used. The reduction was carried out at 50 bar hydrogen pressure in an aqueous solution buffered to pH 7. Thus, 5,6,7,8-tetrahydrofolic acid (2) was obtained which contains a new asymmetric center at C-6 of the pterine system. Therefore, in combination with the (S) configuration of the natural L-glutamic acid part of the molecule two diastereomers with (6S,S) and (6R,S) configuration arise. The relatively unstable tetrahydrofolic acid (2) was converted into its 5-formyl derivative folinic acid (4) by treatment with methyl formate/formic acid in a 5:1 mixture of DMSO/pyridine. The Ca salt of folinic acid (4) is the widely used drug leucovorin. The diastereomers were separated by silica gel HPLC. To the column bovine serum albumine (BSA) is covalently bound. With optically active rhodium(I)/diphosphane catalysts, immobilized on silica gel supports, a diastereoselectivity of up to 90% could be achieved in the hydrogenation of folic acid (1).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300109
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  • 23
    Electronic Resource
    Electronic Resource
    Conformational Mobility and Preferences of Allyl-Type Organometallic Intermediates: Dodec-2-enylpotassium (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 83-88 
    Details
    ISSN: 0009-2940
    Keywords: Torsional (Z/E) isomerization ; Selectivity, regio- and stereo- ; Allylsilanes ; Allylic oxidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alk-2-enylpotassium compounds having the endo conformation are synthetically very valuable precursors of (Z)-olefinic derivatives substituted at the outward allylic position. They may be generated by „stereoconservative‘ metalation of the readily available (Z)-alk-2-enes by using the superbasic mixture of butyllithium and potassium tert-butoxide or by metalation under similar conditions of stereorandom mixtures of alk-2-enes or alk-1-enes followed by torsional isomerization of the concomitantly formed exo conformers to the thermodynamically more stable endo species. The principal factors that dictate the rate and the extent of the endo/exo equilibration are the substrate geometry, the solvent, the temperature, the reagent stoichiometry, and catalysis.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300113
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  • 24
    Electronic Resource
    Electronic Resource
    Organophosphorus Compounds, 114. Tetracyclic Phosphorus-Aluminium-Carbon Compounds - Synthesis by Cooligomerization of Kinetically Stabilized Phosphaalkynes with Trialkylaluminium CompoundsDedicated to Professor Michael Hanack on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 255-259 
    Details
    ISSN: 0009-2940
    Keywords: Phosphaalkynes ; Triorganoaluminium compounds ; Cooligomerization ; Cage compounds ; Aluminium compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When the trialkylaluminium reagents 5 are allowed to react with phosphaalkynes 4 in n-pentane, a highly selective phosphaalkyne cyclotrimerization with incorporation of two organometallic units occurs (→ 6). The tetracyclooctane derivatives 6a-e represent the first examples of phosphorus-aluminium-carbon cage compounds. The polycyclic products 6 are able to function as ligands in transition-metal complexes (→ 7), which is illustrated by the reactions of 6b, c with nonacarbonyldiiron and pentacarbonyl(tetrahydrofuran)tungsten, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300219
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  • 25
    Electronic Resource
    Electronic Resource
    On the Ligating Properties of Sulfonate and Perchlorate Anions Towards Zinc (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 283-289 
    Details
    ISSN: 0009-2940
    Keywords: Zinc ; Sulfonate ligands ; Perchlorates ; Coordination modes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Attempts are reported to incorporate sulfonate and perchlorate anions as ligands in zinc complexes of tripodal ligands. Using tris(benzimidazolylmethyl)amine (BIMA) only the aqua complexes [ (BIMA)Zn-OH2](RSO3)(ClO4) and [(BIMA)Zn-OH2](RSO3)2(R=CH3, CF3, p-tolyl) were accessible. Using substituted pyrazolylborates (Tp*), the same three sulfonate anions were found to be ligands in the complexes Tp*Zn-OSO2R. Spectroscopic evidence for perchlorate coordination in Tp*ZnClO4 · 2 DMSO conflicts with crystallograpic evidence against it in Tp*ZnClO4 · pyridine. The crystal structures of [(BIMA)Zn-OH2](CH3SO3)2, TpCum,MeZn-OS02CH3, TPtBu,MeZn-OSO2C6H4-p-CH3, and [TpCum,MeZn · NC5H5]ClO4 were determined.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300223
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  • 26
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    Multiple Bonds Between Main-Group Elements and Transition Metals, CLXIV. Alkylrhenium(VI) Oxides-Synthesis and Characterization (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 295-298 
    Details
    ISSN: 0009-2940
    Keywords: Rhenium ; Oxides ; Alkyl ligands ; Dirhenium compounds ; Metal-metal interactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Most alkylrhenium(VII) oxides, e.g. ((cyclo)-C3H5)Re03 (2) are rather sensitive to temperature and moisture with the prominent exception of methyltrioxorhenium (1). The corresponding alkylrhenium(VI) oxides of formula [RR′(O)- Re(μ-O)]2 [R=R′=(cyclo)-C3H5 (3), iPr (4); R=CH3, R′=C2H5 (5), R=CH3, R′=iPr (6)] are much more stable in this regard. They can be handled in air at room temperature. They were synthesized from Re207 and dialkylzinc precursors, fully characterized and are available in much higher yields than their ReVII congeners. Mixed tetraalkyltetraoxodirhenium(VI) complexes (R # R′) synthesized from 1 and dialkylzinc compounds form as a mixture of cis/trans isomers. They are oily liquids at room temperature. The Re=O and Re-Re stretching force constants as a measure of the bond strengths, were determined from IR and Raman data.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300225
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  • 27
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    Heterobimetallic Complexes with a Propynylidene C3-Bridge: General Synthetic Routes to Bimetallic Ethynylcarbene Complexes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 479-488 
    Details
    ISSN: 0009-2940
    Keywords: Heterobimetallic complexes ; Carbene complexes ; Alkynes ; Coupling reaction ; Bridging ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sequential reaction of the dimethylamino(trimethylsilylethylnyl)carbene complexes [(CO)5M'=C(NMe2)C≡CSiMe3] [M' = W (1a)] with KF/THFMeOH, nBuLi and transition metal halides, [XMLn], affords heterobimetallic propynyliden complexes of the type [(CO)5M'=C(N-Me2)C≡CMLn] [MLn = Ni(PPh3) Cp (4a, b). Ni(PMe2Ph)2- {Mes) (Mes=2,4,6-C6H2Me3) (5a), Rh(CO)(PPh3)2 (6a), Fe(CO)2Cp (7a,b)]. In contrast, reaction of 1a with MeLi · LiBr and [IFe(CO)2Cp] yields the novel N-metallated complex [(CO)5W=C{N(ME)Fe(CO)2Cp}C≡CSiMe3] (8a). The complexes [(CO)5M'=C(NMe2)C≡CMLn=Fe(CO)2Cp (7a, b), Ru(CO)2Cp (10a,b), Ru(CO)(PPh3)Cp (11a), Mn(CO)5 (12a), Re(CO)5 (13a)] are accessible by Pd-catalyzed coupling of the C-stannylated carbene complexes [(CO)5M'=C-(NMe2)C≡CSnBu3] (9a, b) with [XMLn]. The related monomethylaminocarbene complexes [(CO)5M'=C(NHMe)C≡ CSnBu3] (16a, b), obtained by stannylation of [(C))5M'=C(NHMe)C=CH] (15a, B) with Bu3SnNEt2, react with [IFe(CO)2Cp] to give the bimetallic complexes [(CO)5M'=C(NHMe)C≡CFe(CO)2Cp] (17a, b). The complexes 4a, 5a, 7a and 10a were characterized by X-ray structural analysis. The spectroscopic and structural data suggest that the two metal centers in 4-7, 10-13, and 17 interact only weakly.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300407
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  • 28
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    Diazosulfonate Substitutents: A Route to Transition-Metal Complexes with Switchable Water Solubility (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 515-520 
    Details
    ISSN: 0009-2940
    Keywords: Water-soluble ligands ; Diazo compounds ; Photolysis ; Cleavage reactions ; Zinc ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The single-crystal X-ray structure analysis of the diazosulfonate p-H2N-C6H4-N=N-SO3Na 3 features a Z configuration of the diazo moiety and a nitrogen-sulfur bond. Each sodium atom is coordinated by one diazosulfonate substitutent in a chelating manner. Upon reaction of 3 with excess salicylaldehyde, the highly water-soluble Schiff base ligand 6 is obtained in good yield. Treatment of ZnCl2 with 2 equiv. of 6 gives the zinc complex 7. In all cases, the solubilizing diazosulfonate groups can be cleaved off photolytically, which offers an opportunity to precipitate the molecules from their aqueous solutions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300411
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  • 29
    Electronic Resource
    Electronic Resource
    Organoamido- and Aryloxolanthanoids, 15Part 14: Ref. [1a].. Organometallic Compounds of the Lanthanoids, 116Part 115: Ref. [1b].. Syntheses of Low Coordination Number Divalent Lanthanoid Organoamide Complexes, and the X-ray Crystal Structures of Bis[(N-2,6-diisopropylphenyl)(N-trimethylsilyl)amido]bi(tetrahydrofuran)samarium(II)and -ytterbium(II) (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 409-415 
    Details
    ISSN: 0009-2940
    Keywords: Mercury ; Lanthanides ; Lanthanoid(II) complexes ; (N-2,6-Diisopropylphenyl)(N-trimethylsily)amide complexes ; Bis(trimethylsilyl)amide complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Mercury(II) amide complex Hg[N(SiMe3)(2,6-iPr2C6H3)]2 (1) was prepared by reaction of HgBr2 with Li[N(SiMe3) 2,6-iPr2C6H3)] in diethyl ether solvent. Redox transmetallation reactions of 1 with elemental samarium, europium or ytterbium in THF solvent (THF = tetrahydrofuran), generated the novel divalent complexes Ln[N(SiMe3)(2,6-iPr2C6H3]2(THF)2 with Ln = Sm (2), Eu (3) and Yb (4). 4 was also synthesized by reaction of elemental ytterbium, HgPh2 and HN(SiMe3)(2,6-Me3)2]2(THF)2 [Ln = Sm (5), Yb (6)] by reaction of the metals with HgPh2 and HN(SiMe3)2. Thermal desolvation of 4 under high vacuum gave Yb(N)(SiMe3)2,6-iPr2C6H3)]2 (THF) (7), whereas under identical conditions 6 yielded the solvent-free complex [Yb[N{SiMe3)2]2]2. (8). The new compounds 1-4 and 7 are hydrocarbon soluble and 171Yb-NMR spectra were recorded for 4, 6, 7 and 8. X-ray crystal structure determinations of 2 and 4 revealed four-coordinate, distorted tetrahedral metal environments augmented by weak Ln…ipso-C(aryl) interactions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300316
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    Electronic Resource
    Electronic Resource
    Recent Developments in the Chemistry of Covalent Azides (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 443-452 
    Details
    ISSN: 0009-2940
    Keywords: Ab initio calculations ; Azides ; Density functional calculations ; Covalent azides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The experimental and theoretical chemistry of covalently bound azides is an area that has seen considerable renaissance over the past 10 years. This review is not exhaustive in scope but rather focuses on and highlights certain aspects in this field. In particular, the stability and dissociation of HN3 is discussed at a very high level of theory (CASSCF and MCSCF-CI) and compared and contrasted with experimental data and results from „medium“-level ab initio computations (MP2, B-LYP). From these results credence is given to those values calculated for larger systems and heavy elements for which very high level computations are not possible. The experimentally well-characterized covalent halogen azides (XN3, where X = F, Cl, Br, I) as well as the heavy-element group-15 compound Sb(N3)3 are discussed. The review also includes discussion of the bond properties of the highly unstable N-bound azides ON-N3 and (FSO2)2N-N3. In the final chapter attention is drawn to the recently predicted and eventually experimentally verified elusive species OCN-NCO, which is isoelectronic to the hitherto unknown diazide N6.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300403
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    Divalent Tin and Lead Compounds EX2 Acting as Bridging Ligands in [{(CO)5M}2EX2]2- (E = Sn, Pb; M = Cr, Mo, W): Preparation and PropertiesDedicated to Professor G. E. Herberich on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 687-699 
    Details
    ISSN: 0009-2940
    Keywords: Tin ; Lead ; 119Sn NMR ; Salt metathesis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of Na2[M2(CO) 10] (M = Cr, Mo, W) with SnHal2 (Hal = Cl, Br) is a well established procedure for the synthesis of anions of type A, [{(CO)5M)SnHal3]-. Conditions are described which, for the same type of procedure, result in the additional formation of dianions of type B, [{(CO)5M}2SnHal2]2-. Procedures for separating these two types of anions in the form of their stable [Ph4P]+ or [nBu4N]+ salts by appropriate salt metathesis are presented. The structures of theses species have been characterized by X-ray analysis of three salts containing type A anions and two salts containing type B anions. The reactivity of the type B salts containing the bulky cations [Ph4P]+ or [nBu4N]+, respectively, is remarkably low; the salts are, however, transformed into highly reactive sodium salts by further metathesis with Na[BPh4]. In such salts the halide substitutents are easily exchanged as shown by the synthesis of ]})CO(5Cr}2oxinato]- (4)- from [Na-(THF)x]2[{(CO)5Cr}2SnCl2] and sodium 8-oxoquinolate, Na[C9H6NO]. The structure of the anion, 4 is compared to the structure of [[(CO)5Cr)SnCl2· THF] and sodium 8-oxochinolate. The preparation of the dinuclear anions [{(CO)5Cr}2E(OOCCH3)2]2- (E = Sn, 2g; E = Pb, 3) is accomplished by the reaction of [Ph4P]2[Cr2(CO)10] with the corresponding acetates E(OOCCH3)2. While 2g and 3 are formal analogues of the type-B anions, their structures reveal an asymmetrical η2-coordination of the two acetato ligands, in each case ending up in a 4+2 coordination for the main group centres, instead of the four-coordination observed for [{(CO)5M}2SnHal2]2-, All compounds have been characterized by usual spetroscopic and analytical techniques. X-ray analyses have been performed for selected examples. 119Sn-NMR data are presented for all of the compounds which contain tin-centred ligands.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300604
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    Organophosphorus Compounds, 118Part 2: 117: Ref1. Reactions of 1-Chloro-1H-phosphirenes with Nucleophiles (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 711-723 
    Details
    ISSN: 0009-2940
    Keywords: Phosphorus heterocycles ; 1H-Phosphirenes ; Nucleophilic substitution reactions at 1H-phosphirenes ; Metal-complexation of functionalized 1H-phosphirenes ; Carbonyl complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The halogen atoms in the 1-chloro-1H-phosphirenes, 5a-c, are easily substituted on reaction with organolithium and Grignard reagents, 14a-p, with formation of the corresponding O-, N-, C-, Si-, and Ge-substituted 1H-phosphirenes, 15a-t. C1/H exchange reactions also occur on reaction with lithium metal hydrides (5a → 17). Furthermore, substitution reactions are also realized with the alkali metal borates, 18a-g (→19a-g); the same is true for reactions with trimethylsilyl cyanide and azide (→22a-d). Some of the substitution products have been characterized in the form of their metal complexes, 16, 23, 24, and 25.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19971300607
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    Synthesis of Germatranyl Derivatives of Esters of Carboxylic Acids via Organometallic (Si, Ge, Sn) Reagents (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 739-746 
    Details
    ISSN: 0009-2940
    Keywords: Germatranes ; Organotrihalogenogermanes ; Organometallic (Si, Ge, Sn) reagents ; Transmetallation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Trialkylstannyl esters of tris(2-hydroxyalkyl)amines, N(CH2CHROSnAlk3)3 (9-11 (R = H, Me; Alk = Et, Bu), react with X3GeC(R1)(R2)COOR3 (12-17) (X = Cl or Br; R1, R2=H, Me, Ph, SiMe3, COOEt; R3=Me, Et) to give esters of α-germatranylcarboxylic acids, N(CH2CHRO)3GeC(R1)(R2)-COOR3 (1-8), in high yields. The synthesis of esters 12-17 is reported. Esters of α-germatranyldiphenylacetic acid 24 and 25 can be obtained by treatment of diphenylketene with Et3SnOMe to give in situ Et3SnC(Ph2)COOMe (23), followed by reaction with GeCl4 to give in situ Cl3GeC(Ph2)COOMe (22 and further reactions with 9 or 11, respectively. Reduction of germatrane 6 with LiAlH4 in diethyl ether leads to cleavage of the germanium-carbon bond with subsequent formation of (2-hydroxyethyl)trimethylsilane. The crystal structures of 3, 6 and 7 are reported. 1-Acyloxygermatranes 26 and 27 are obtained by treatment of 1-methoxygermatrane (28) with diphenyl- and dichloroacetic acid, respectively.
    Additional Material: 4 Ill.
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    Base-Induced Synthesis of a Tetrastannatriazabicyclo[3.1.1]heptane from Tris)dimethylchlorostannyl)amineDedicated to Professor W. Sieber on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 765-769 
    Details
    ISSN: 0009-2940
    Keywords: Tin - Nitrogen cage compounds ; Sn—X—Sn intramolecular bridges ; Distannylamine pyridine adduct ; Tin ; Moessbauer spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tris(dimethylchlorostannyl)amine (2a) reacts with pyridine in a 3:4 molar ratio to produce the tin-nitrogen containing bicyclo[3.1.1]heptane (3) with elimination of the adduct Me2SnCl2·2 py. Treatment of the distannylamine 2,6-[Pr2H3N(SnMe2Cl)2 (4) with pyridine, however, leads to the formation of the 1:1 pyridine adduct 4 and this can be regarded as a model to explain the route to 3. The molecular structures of 3 and 5 were determined by multinuclear magnetic resonance spectroscopy in solution, as well as by X-ray structure analysis of their crystals. Typical structural features for both compounds are intramolecular Sn—X—Sn bridges. Support for the structures comes from MS fragmentation patterns, IR spectra, and the Mössbauer spectra.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300615
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    Thermal Reactions of 5-Alkylidene-4,5-dihydro-3H-1,2,4(λ3)-diazaphospholes (4-Phosphapyrazolines) - A Route to Various P—Heterocycles and to 2-PhosphabutadienesDedicated to Professor M. Hanack on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 779-788 
    Details
    ISSN: 0009-2940
    Keywords: 1,2,4-Diazaphospholes ; Phosphiranes, alkylidene- ; 2-Phosphabutadienes ; Phosphorus heterocycles ; pyrazolines, thermolysis ; Rearrangements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 5-alkylidene-4,5-dihydro-3H-1,2,4(λ3)-diazaphospholes (4-phosphapyrazolines) are thermally much more stable than related compounds without the exocyclic double bond. Thermolysis reactions typically occur in the range 110-150°C in toluene solution, and different, mostly competing, reaction pathways are observed. Thermal extrusion of nitrogen from 8a-g gives rise to β-phosphanaylsiloxyalkenes 10, benzo[c]-phosphole derivatives 11, 14 and 115, (β-siloxyalkylidene)-Phosphiranes 12, and dihydro-1,3-oxaphospholes 13. The thermolysis of 5-alkylidene-4,5-dihydro-4-trimethylsilyl-3-trimethylsilyloxy-3H-1,2,4-dizaphospholes 17 afforded three products, including the highly substituted and stable 2-phosphabutadienes 18 formed by nitrogen extrusion and rearrangement. Finally, the 4-chloro-3-trimethylsilyloxy-substituted heterocycle 21 was transformed at 170°C into 4H-1,2,4-diazaphosphole 23. The structures of 13c and 18a were determined by single-crystal X-ray diffraction.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300617
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    N-Alkylation of Ammine - Undecahydro-Closo-dodecaborate(1-)Dedicate to Prof. Dr. Walter Siebert on the occasion of hbis 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 795-799 
    Details
    ISSN: 0009-2940
    Keywords: Boron ; Alkylations ; N ligands ; Dodecaborate ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of the ammine-undecahydro-closo-dodecaborate(1-) anion with alkyl halides have been studied in detail. The degree of alkylation of the nitrogen was found to be dependent upon the steric demands of the alkyl groups. The derivatives were characterized by NMR and infrared spectroscopy. Four compounds were crystallized for single crystal X-ray diffraction studies. The tetrahedral coordination of the nitrogen atom of the bis-alkylated derivatives was found to deviate towards planarity with increasing steric hindrance of the substitutents. - The syntheses, crystal structures, and spectral properties of four N-alkyl derivatives of [H3N—B12H11]-, ammine - undecahydro-closo-dodecaborate(1-) (3), are reported. Alkylation of 3 with ethyl iodide was achieved in dimethyl sulfoxide using potassium hydroxide as base. This led to orthorhombic crystals of [N(nC4H94][(CH3CH2)3N—B12H11] (4). The reaction of 3 with benzyl chloride resulted in the bisbenzylated product, isolated as triclinic crystals of [PPN][(C6H5CH2)2 NH—B12H11] (5). The alkylation of 3 with 2-bromopropane gave a mixture of the mono- and bisalkylated products. The monoalkylated derivative [PPN][(CH3)2CH)NH2-12H11] (6, crystallized in the triclinic space group p1) and the bisalkylated product [PPN]{[(CH3)2NH—B12H11) (7, monoclinic, P21./c) were separated on the basis of their different water solubilities. The solid-state structures of the compounds 4-7 revealed a slight distortion of the B12 icosahedron. The length of the B(1)-N(1) bond was found to be dependent on the steric requirements of the attached amine, e.g. primary amine 〈 secondary amine 〈 tertiary amine. This is demonstrated by the variation in the B—N bond length; from 157.8(2) pm for 6, 158.5(5) pjm for 5, 160.0(3) pm for 7, to 163.7(6) pm for 4.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300619
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    Unusual Ring-Closure Reactions During the Oxidation of 1,1′-Bi(3-methylphosphol-2-ene) with Hexafluoroacetone  -  Formation of a Tricyclic Fluorine-Containing PhosphoraneDedicated to Professor Rudolf Taube on the occasion of hbis 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 819-822 
    Details
    ISSN: 0009-2940
    Keywords: Hexafluoroacetone ; Phosphorus, pentacoordinated ; Diphosphane diselenide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reduction of the isoprene - PCl3 adduct 1 with magnesium powder, or with Si2Cl6, furnished P-chloro-3-methyl-phosphol-2-ene, 2, in satisfactory yield. Further reduction of 2 with Si2Cl6 gave the new trichlorosilyl-3-methylphosphol-2-ene, 3. The reaction of 2 with magnesium powder, with 3, or with 1/2 equivalent of Si2Cl6 provided the new γ3P-γP-diphosphane 1,1′-bi(3-methylphosphol-2-ene) 4. Reduction of 4 with Si2Cl6 led to 3. Oxidation of 4 with selenium gave the 1,2-diphosphane diselenide, 5. The oxidation of 4 with hexafluoroacetone led to a mixture of products, from which a novel tricyclic phosphorane 6 was separated. the structure of 196 was determined by X-ray diffraction; the coordination geometry at phosphorus in distorted trigonal bipyramidal, with a very long equatorial P - C(CF3)2 bond of 193.2(2) pm.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300623
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    Organophosphorus Compounds, 119Part 118: Ref.. The Phosphaalkyne Cyclotetramer System  -  Syntheses, Valence Isomerizations, and Reactions (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 823-834 
    Details
    ISSN: 0009-2940
    Keywords: Phosphaalkynes ; Phosphaalkyne cyclotetramers ; Cage compounds ; Valence isomerization ; Cyclotetramerization ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In contrast to their all-carbon analogues, phosphaalkyne cyclooligomers only became accessible a few years ago. A milestone in the chemistry of cyclotetramers was the synthesis and structural characterization of the tetraphosphacubane 5, obtained as a thermolysis product of tert-butylphosphaacetylene (1). Since then, the construction of eleven cyclotetramers has been achieved, covering seven different frameworks (A-G). As a consequence of the use of kinetically stabilized phosphaalkynes as starting materials, all known cyclotetramers bear sterically demanding substituents (tert-butyl, tert-pentyl, 1-adamantyl). Cyclotetramerizations are not only achieved by thermolysis of 1, but also by alternative and selective routes such as transition-metal-mediated, Lewis acid- and base-induced processes, as well as by cycloadditions to phosphaalkyne cyclotrimers. Interestingly, these tetramers can be interconverted by various valence isomerizations. The results of thermal and photochemically-induced rearrangements are in good agreement with MO calculations carried out for the parent compounds. Phosphaalkyne cyclotetramers exhibit a highly interesting reactivity and other peculiar features. One outstanding example is the tetraphosphacubane 5, which shows unusual structural and spectroscopic properties as a result of its unique bonding arrangement.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300703
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    2-Phosphanylphosphinines as Bridging Ligands for Dinuclear Transition Metal Carbonyls (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 843-849 
    Details
    ISSN: 0009-2940
    Keywords: P ligands ; Phosphorus heterocycles ; 2-Phosphanylphosphinines ; Dinuclear complexes ; Metal carbonyls ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2-phosphanyl-4,5-dimethylphosphinines 1-5 are powerful bridging ligands able to stabilize metal-metal single and triple bonds between low-valent transition metal centres. Their reaction with Mn2(CO)10 in refluxing xylene yields the corresponding Mn2(CO)8 complexes 6 and 7. Reaction with [Fe2Cp2(CO)4] under UV irradiation similarly yields the Fe-Fe-bridged Fe2Cp2(CO)2 complexes 8 and 9. An additional observation is that the 2-phosphininyl-3,4-dimethylphosphaferrocene 10 is formed upon reaction of the 2-phospholylphosphinine 5 with [Fe2Cp2(CO)4] at high temperature under CO pressure. A clean addition occurs at the Mo≡Mo triple bond of [Mo2Cp2(CO)4] to give the Mo-Mo single-bonded complexes 11-15. The thermolysis of these complexes succeeds when the phosphanyl group is a phosphonite P(OEt)2 (13) or P(OAr)2 (14), affording cleanly the Mo2Cp2(CO)4 triple-bonded complexes 16 and 17, respectively. The metal-metal triple bonds of these complexes readily add two molecules of CO to reform 13 and 14, or one molecule of tBu-N≡C to give 18 and 19. The X-ray crystal structure analysis of the MO2C2(CO)4 complex 13a, with the 2-P(OEt)2- phosphinine, shows a gauche orientation of the two Cp rings and very short P-Mo bonds of 2.3565(4) and 2.406(2) Å to the phosphinine and P(OEt)2 groups, respectively.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300706
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    On the Polymorphism of White PhosphorusDedicated to Professor Gottfried Huttner on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1235-1240 
    Details
    ISSN: 0009-2940
    Keywords: Phosphorus ; Phase transitions ; Molecular crystal ; Crystal growth ; Low-temperature crystal structure ; Librational motion ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: White phosphorus occurs in three modifications. The α form, which exists at roomtemperature, transforms reversibly to the β form at -77°C. The α · β transformation may be strongly delayed. Quenching the α form to -185°C followed by slow warming results in an exothermic reactions with formation of the γ form which transforms into the β form at -120°C in an endothermic reaction. A transition β · γ is not observed. The γ form is characterized by its powder diagram. The structure of the β form is redetermined from a single crystal at -185°C (P., α = 547.88(5), b = 1078.62(11), c = 1096.16(11)pm, α= 94.285(8), β = 99.695(7), γ = 100.680(7)., V = 623.79(10) · 106 pm3, Z = 6 formula units per cell). The P4 molecules exhibit pronounced librational motion in spite of the low temperature of investigation. The arrangement of the centers of the tetrahedra corresponds to the atom positions in the γ-plutonium structure, which is discussed in relation to the bcc structure.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300911
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  • 41
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    Chiral Polysiloxane-Fixed Metal 1,3-Diketonates (Chirasil-Metals) as Catalytic Lewis Acids for a Hetero Diels-Alder Reaction -Inversion of Enantioselectivity Upon Catalyst -Polymer Binding (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 879-885 
    Details
    ISSN: 0009-2940
    Keywords: Asymmetric catalysis ; Cycloadditions ; Lewis acids ; Polymers ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A dimethylpolysiloxane chain is covalently bound to the monomeric Lewis acid catalyst (1R)-(+)-oxovanadium(1V) bis[3- heptafluorobutanoylcamphorate] [(+)-5a] at the C-10 position of the camphor moiety yielding the novel chiral polymeric (1S)-( +)-oxovanadium(1V) bis[3-heptafluorobutanoylcamphorate] -dimethylpolysiloxane [( +)-6a][1]. The Lewis acid promoted hetero Diels-Alder reaction of trans-l-methoxy-3-(trimethylsilyloxy)- 1,3-butadiene (1) and benzaldehyde (2) is studied in the presence of the enantiomerically pure monomeric (5a, 5b) and polymeric (6a, 6b) catalysts. The monomeric and polymeric catalysts of identical chirality[1] invoke opposite enantioselectivities toward the formation of 2-phenyl- 2,3-dihydro-4H-pyrone (4). This remarkable result is corroborated by numerous control experiments. Thus, it is demonstrated that the environment of the active site of the catalyst is changed when the complex is fixed to a polymeric chain. In contrast to 5 and 6, the monomeric 12 and polymeric 13 europium(III) tris[3-heptafluorobutanoylcamphorates] of identical chirality invoke the same enantioselectivity toward the formation of 4. The concept of polymer attachment is utilized to recover the catalyst from the reaction mixture by precipitation and to recycle it for subsequent catalytic runs.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300711
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  • 42
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    Cp3Zr(acetonitrile)+: Structure of an Electron-Rich Organometallic d0-Cation (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 899-902 
    Details
    ISSN: 0009-2940
    Keywords: Cp3Zr complexes ; Cationic organometallic Lewis acid ; d0-Configured metal complex ; Acetonitrile ; crystal structure analysis of Zirconium ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The organometallic salt [Cp3Zr(N≡C-CH3)]+ [CH3B-(C6F5)3]- (3a) has been prepared by treatment of Cp3ZrCH3 with B(C6F5)3 followed by the addition of acetonitrile. X-ray crystal structure analysis of 3a shows that its cation consists of three uniformly coordinated η5-cyclopentadienyl ligands about the zirconium atom. The acetonitrile ligand is end-on coordinated. In the linear [Zr] -N≡C-CH3 unit the C≡N triple bond [N-C2 1.126(5) Å] is slightly shorter than in the free acetonitrile molecule [dC≡N = 1.141(2) Å], the structure of which was determined as a reference by X-ray diffraction of a crystal obtained by IR-laser-induced zone melting on the diffractometer.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300714
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    Benzophenoneimine Complexes of Copper(1)Dedicated to Professor J. Strähle on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 947-950 
    Details
    ISSN: 0009-2940
    Keywords: Copper ; N ligands ; Copper(I) complexes ; (Imine)copper(I) complexes ; Ketimines ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of [(MeCN)4Cu]BF4 with two or three equivalents of benzophenoneimine lead to the formation of [(Ph2C=NH)2]BF4 (1) and [ (Ph2C=NH)3Cu]BF4 (2), respectively. A further equivalent of the ligand does not coordinate to the cation of complex 2. The crystal structures of both compounds were determined. 1 shows a linearly two-coordinated copper(I) center with a Cu-N distance of 1.877(2) Å. In compound 2 a distorted trigonal planar coordination of copper is observed with N-Cu-N angles of 114.5(2), 112.9(2) and 132.4(2)°, corresponding to two nearly equal Cu-N distances [Cu-N2 1.947(5) and Cu-N3 1.934(5) Å] dnd a significantly longer third one (Cu-N1 2.011(5) Å]. A comparison of these data with recently determined structures of bis(benzophenoneimine)silver(I) and -gold(I) complexes shows that the covalent radii of the monovalent coinage metals decrease in the order Ag(I) 〉 Au(I) 〉 Cu(I).
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300721
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    Organoantimony Oxides: Preparation and Crystal Structures of [(2-PhOC6H4)O (C6H4)2Sb]2O2 and (o-Tol2Sb)4O6Dedicated to Prof. Dr. Gottfried Huttner on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 959-961 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Air oxidation of (Oxydi-2,1-phenylene)(2-phenoxyphenyl)stibane (1) gives the phenoxystibane oxide [(2-PhOC6H4)O(C6H4)2Sb]2O2 (2). Single crystals of (o-Tol2Sb)4- O4(O2)2 (3) were obtained by air oxidation of o-TolSb-(SiMe3)2. Crystal structures of 2 and 3 are reported.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300724
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    Zinc Pyrazolylborate Complexes with Phenoxide and Alkoxide LigandsDedicated to Professor Wolfgang Beck on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 975-980 
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    ISSN: 0009-2940
    Keywords: Zinc complexes ; Phenoxide complexes ; Alkoxide complexes ; Terminal alkoxide ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The zinc hydroxide complexes Tp*Zn-OH of highly substituted pyrazolylborate ligands react with phenols, and alcohols, of sufficient acidity, in a condensation reaction with release of H2O. Starting with phenols the following were attached:phenolate, p-nitropehnolate, o-vanillinate, o-hydroxymethylphenolate, o,o-bis(hydroxymethyl) -p-methylphenolate. Whilst aliphatic alcohols and benzyl alcohol did not react, their derivatives, with highly electronegative substituents could be incorporated. Thus, the arylmethoxides OCH2C6F5 and OCH2C6H4NO2-p, as well as the alkoxides OCH2CF3 and OCH2CCl3, were attached. 2-Mercaptoethanol was bound via its thiolate function. The crystal structures of TpCum,Me ZN-OC6H4NO2-p,TpCum,Me ZN-OCH2-C6F5, TpCum,Me ZN-OCH2CF3, TpCum,Me ZN-OCH2CCl3 and TpCum,MeZn-SCH2CH2OH were determined.
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    URL: http://dx.doi.org/10.1002/cber.19971300727
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    Pseudoelement Compounds, XPart IX: Ref. Synthesis and Crystal Structure of New Complexes of the Type trans-[Pt(H)X(PPh3)2 with Cyanamide and Cyanomethanide LigandsDedicated to Professor S. Engels on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1007-1012 
    Details
    ISSN: 0009-2940
    Keywords: Platinum ; Nitrocyanamide ; Nitrosodicyanomethanide ; 1,1,3, 3-Tetracyano-2-azapropenide ; 1,1,2,3,3-Pentacyanopropenide ; Hydrido complexes ; Coordination modes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The new coordination compounds trans-[Pt(H)X(PPh3)2] with NCN- and C(CN)2-functionalized anions (X- = [N(O)C(CN)2]-, [NO2NCN]-, [N{C(CN)2}2]-, [NCC{C-(CN)2}2]-, have been characterized by 1H-, 31P-, 13C-NMR, and IR spectroscopy and elemental analyses the crystal structures of trans-[Pt(H)N(O)C(CN)2(PPh3)2], trans- [Pt(H)N{C(CN)2}2(PPh3)2], and trans-[Pt(H)NCC{C(CN)2}2-(PPh3)2) have been determined by X-ray diffraction. Remarkably, [N(O)C(CN)2]- is coordinated through the central nitrogen atom, while [N{C(CN)2}2]- and [NCC(C(CN)2]2]- are bonded through terminal nitrogen atoms of a C(CN)2 unit.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300730
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    New Coupling Reactions and Phosphorylations Using Organozinc Reagents (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1021-1027 
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    ISSN: 0009-2940
    Keywords: Zinc ; Chirality ; Cross-coupling ; Phosphorylations ; Catalysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This Microreview on the chemistry of organozinc reagents starts by briefly showing the methods of preparation of organozinc compounds and then discusses the considerable synthetic utility of zinc organometallics for the formation of new carbon-carbon bonds in the presence of transition-metal catalysts. Finally, the use of organozinc chemistry for the preparation of polyfunctional and chiral phosphanes is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300802
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    Synthesis and Structures of Bis(tetramethylipiperidino)aluminum Halides-X-ray Crystal Structures of tmp2AlX (X = Cl, Br, I) and [tmp2A1(μ-F)l2 (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1047-1052 
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    ISSN: 0009-2940
    Keywords: Bis(tetramethylipiperidino)aluminum halides ; Alkoxy((tetramethylpiperidino)aluminum halides ; 27Al-NMR spectra ; Aluminum ; Amides ; Synthetic methods ; Bridging ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Lithio-2,2,6,6-tetramethylpiperidine [Li(tmp)] reacts with AlX3 (X = Cl, Br) in diethyl ether/ n-hexane solution to generate the products of substitution and ether cleavage, [tmpAl(X)(μ-OEt)], (la, X = Cl; 1b, X = Br). However, when the reaction is allowed to proceed in n-hexane alone, an almost quantitative yield of compounds tmp2AlX (2a, X = Cl; 2b, X = Br; 2c, X = I) is obtained. According to 27AI-NMR spectroscopy, mass spectroscopy, cryoscopy, and X-ray crystal structure determinations, these compounds are monomeric in the solid state, in solution, and in the gas phase. 2b reacts with AgBF4 yielding the fluoride-bridged dimer (tmp2AlF), 2d, as shown by X-ray crystal structure determination.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300805
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    Structure and Reactivity of Sodium Phenoxide - Following the Course of the Kolbe-Schmitt Reaction (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1461-1465 
    Details
    ISSN: 0009-2940
    Keywords: Kolbe-Schmitt reaction ; Solid-state structures ; Sodium phenoxide ; Solvent Complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solvent-free sodium phenoxide (NaOPh) crystallises as a polymer and forms a polymeric chain in the [0 0 1] direction. The low coordination of the sodium atoms, as evident in the crystal structure, is confirmed by the easy coordination of oxoligands (α-donors). Hence, the four-membered ring chain of the solvent-free sodium phenoxide is separated by oxoligands, and forms partial structures as the polymer fragments. Thus, NaOPh crystallises in THF with the formation of an Na6O6 core, consisting of two face-fused heterocubes, and in N, N, N′, N′-tetramethyl urea (TMU) with the formation of a Na4O4 heterocubane. The solvent-free NaOPh-CO2 complex obtained from the addition of CO2 to a solution of sodium phenoxide is, when exposed to a temperature of 80°C, subject to an irreversible phase transition, as demonstrated by FT-IR and DTA studies. The complex formed at 80°C is, apparently, another intermediate of the Kolbe-Schmitt reaction.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301017
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  • 50
    Electronic Resource
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    1,8-Bis(phosphanyl)naphthalenes: 1,8-Bis[(diethylamino)phosphanyl]-naphthalene, 1,8-Bis(dichlorophosphany)naphthalene, and 1, 3-Dichloro-2,-3-dihydro-1,3-dioxo-2-oxa-1,3-diphosphaphenaleneDedicated to Professor Huns Burger on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1485-1489 
    Details
    ISSN: 0009-2940
    Keywords: Naphthalenes ; Phosphanes ; Phosphorus heterocycles ; Protecting groups ; Strained molecules ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1.8-dilithionaphthalene 1 reacted with bis(dimethylamino)-chlorophosphane to form 1,8-bis[(diethylamino)phosphanyl]-naphthalene 2, whose structure was confirmed by X-ray crystal structure analysis; there are two independent molecules, in which the P(NEt2)2 groups adopt an eclipsed conformation. Reaction of 2 with gaseous HCl gave in low yield 1,8-bis-(dichlorophosphanyl)naphthalene 3, which was characterized by 1H- and 31P-NMR spectroscopy, mass spectrometry and elemental analysis. Attempted recrystallization of 3 led to oxidative hydrolysis which furnished 4, an anhydride of a bis(chlorophosphonic acid), whose structure was elucidated by X-ray crystal structure analysis. The geometry of 4 reveals a relief of strain from the bis (aminophosphane) 2; the naphthalene groups are less distorted and the P atoms are displaced less far from the naphthalene best plane.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301021
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  • 51
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    Coordination Compounds of Coinage Metals with Vinylidenebis(diphenyl-phosphane) and Its Disulfide and Their Reactivity towards NucleophilesDedicated to Professor P. Royo on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1513-1517 
    Details
    ISSN: 0009-2940
    Keywords: Gold ; Silver ; Diphosphane ; Diphosphane Disulfide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vinylidenebis(diphenylphosphane) reacts with gold(I) or gold(III) compounds to give dinuclear {[{Au(C6F5)]2[(PPh2)2C=CH2{] or [Au{PPh2C(=CH2)Ph2P)]2(ClO4)2] or mononuclear complexes ([Au(C6F5)3(PPh2C(=CH2)Ph2P)]}, respectively. The latter reacts with gold(I) or silver(I) compounds to afford dinuclear [[Au(C6F5)3[PPh2C(=CH2)Ph2P}AuX], X=Cl or C6F5) or trinuclear species {[{Au(C6F5)3{PPh2C(=CH2)Ph2P{]2M]ClO4, M=Au or Ag}. No addition of nucleophiles to the C=C double bond is observed in these complexes, which contain the diphosphane acting as bridging or monodentate ligand. (SPPh2)2C=CH2 reacts with AgClO4 to give [Ag{SPPh2C(=CH2)Ph2PS}]2-(ClO4)2or[Ag[PPh2C(=CH2)Ph2P]2]ClO4. The crystal structure of [Au(C6F5)3{PPh2C(=CH2)Ph2P}Au(C6F5)] has been established by X-ray crystallography, and confirms the expected square planar and linear geometry for the Au111 and Au1 centres, respectively.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301026
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  • 52
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    Diastereoselective Synthesis and Molecular Structure of a Bicyclic and a Cage Phosphane (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1547-1550 
    Details
    ISSN: 0009-2940
    Keywords: Phosphane ; 1,3α., 5,7β-Tetrakis(trifluoromethyl)-6,-9-dioxa-2-phosphabicyclo[3.3.1]nonane-3β, 7α-diol ; 1,7-Trifluoromethyl-3,5-methyl1-2,4.8-trioxa-6-phosphaadamantane ; Phosphorus heterocycles ; Ketones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A two-step formal insertion of 1,1,1,5,5,5-hexafluoro- (2a) and 1,111-trifluoropentane-2,4-dione (2b) into the P-H bonds of phosphane gave the primary a-hydroxyphosphanes 3 and 4, precursors for the resulting secondary phosphanes, 6,9-dioxa-2-phosphabicyclo[3.3.l]nonane (6a) and 2,4,8-trioxa-6-phosphaadamantane (7), both formed diastereospecifically. The molecular structures of 6a and 7 were established by single-crystal X-ray structure analysis which revealed two independent molecules for 6a in the unit cell possessing a chair-boat conformation with a C-P-C angle of 95.4(2)°, and a characteristic heteroadamantane geometry for 7, with the corresponding angle being smaller by 4.9°.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301031
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  • 53
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    Reactions of Complex Ligands, LXXVII. Axial-Chiral Metal Carbenes: Synthesis and Structure of 1,1-Binaphthyl-Derived Carbonyl-Carbene Complexes of Chromium (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1605-1609 
    Details
    ISSN: 0009-2940
    Keywords: Axial-chiral complexes ; Biaryls ; Carbene complexes ; Circular dichroism ; Chromium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Axial-chiral mono- and biscarbene complexes of chromium containing the 1,1-binaphthyl skeleton have been obtained in both racemic and enantiopure forms in a one-pot reaction starting from lithiated 2,2-dimethoxy-1,1-binaphthyl (1) and hexacarbonyl chromium via the Fischer route. An X-ray structure analysis of the biscarbene complex 2 reveals that the biscarbene functionalization significantly increases the dihedral angle defined by the biaryl planes. The enantiopure complexes have been characterized by CD spectroscopy.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301108
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  • 54
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    Evidence for Internal Ion Pair Formation upon Insertion of Reactive Alkene in the Zirconium-Carbon Bond of the cp2Zr(μ-C4h6)b(c6f5)3 Metallocene-Boron-Betaine Ziegler Catalyst System (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1261-1267 
    Details
    ISSN: 0009-2940
    Keywords: Single-component metallocene catalyst ; Olefin insertion ; Organometallic ions pairs ; (Alkene)metallocene complex ; Metallocene betaines ; C-C coupling ; Zirconium ; Homogeneous catalysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of the (butadiene)ML2 complexes 1 [ML2 = Cp2Zr (a), Cp2Hf (b), and (.-C5H4CH3)2Zr (c)] with B(C6F5)3 gives the 1:1 addition products (CH2CHCHCH2-B(C6F5_3)ML2 (3a-c). At -40°C the betaine complex 3a inserts one equivalent of methylenecyclopropane to give the regioisomeric insertion products 5a and 6a in a 60:40 ratio. These products exhibit the cyclopropylidene moiety in the α- and β-positions, respectively, relative to zirconium. The corresponding hafnocene complexes 5b and 6b are obtained in a 70:30 ratio starting from 3b. The reaction of 3(a-c) with allene gives a single insertion product (7a-c) in each case where the exo-methylene group is in the α-position to the metal center ([2,1]-insertion). The complexes 5-7 are chiral. They all exhibit a pronounced ·-interaction of the internal -C4H=C5H- double bond of the s̰-ligand chain with the metal center in addition to a metallocene/-C6H2-[B] ion pair interaction. The relative contributions of the cationic metallocene end of the dipolar complexes 5-7 are quite dependent on the steric and electronic properties of the respective metallocene units involved. This is revealed by a comparison to typical 13C-NMR parameters of the complexes 5-7 with a pair of suitable model complexes, namely the ethylene insertion product 4 into the betaine system 3a and its THF adduct 4.THF.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19971300914
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    Tripod Ligands Containing a Mixed P/N/S Doner Set: Synthesis and Coordination Chemistry (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1279-1294 
    Details
    ISSN: 0009-2940
    Keywords: Tripodal ligands ; Aminolytic cleavage of oxetanes ; Tripod molybdenum compounds ; Mixed donor set ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of neopentane-based tripod ligands CH3C(CH2X)(CH2Y)(CH2Z( 3 (X = NR2, NHR; Y = PR2; Z = PR2, SR, S-) in a convergent manner is described. The procedure is based on the aminolytic cleavage of functionalized oxetanes CH3C(CH2OCH2)CH2R 1 by primary or secondary amines, leading to functionalized amino alcohols CH3C(CH2NHR)(CH2OH)(CH2R) or CH3C(CH2NR2)-(CH2OH)(CH2R) 2. The appropriate activation of the R (e.g. OR) and OH groups present in 2 allows for substitution vs. SR or PR2 donor functions. Depending on the nature of the groups present in each reaction step, various protection and groups present in each reaction step, various protection and deprotection steps have to be taken in the course of this type of preparation of the tripod ligands 3. By reaction with (CH3CN)3Mo(CO)3, ligands 3 form Mo(CO)4 derivatives 4 or Mo(CO)3 derivatives 5, depending on the reaction conditions. In compounds 4, the ligands are coordinated in a bidentate mode with the soft donor atoms (P, S) coordinated and the hard donor function playing the role of the dangling arm. In the trihapto bonding mode present in 5, all three donor functions, two soft (P, S) and one hard (NHR′, NR′2), are coordinated. The two types of coordination compounds may be interconverted: 4e (X = NMe2′ Y = PPh2, Z = SiPr) with a non-coordinating CH2NMe2 group is transformed into 5c upon photolytic decarbonylation. Under 1 bar CO at 20°C, 5c reverts to 4e. X-ray structure analysis of a series of compounds of types 4 and 5 reveals characteristics of the relevant conformational patterns. All compounds have been fully characterized by the standard analytical techniques (NMR, MS), as well as elemental analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300917
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    Neutral Gold(I) Complexes with Mixed Phosphorus LigandsDedicated to Professor Wolfgang Beck on the occasion of his 65th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1333-1338 
    Details
    ISSN: 0009-2940
    Keywords: Gold ; Gold(I) complexes ; Phosphinite complexes ; Phosphite complexes ; Configuration determination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of compounds (R3P) AuMe with diphenylphosphinous acid Ph2P(O)H affords methane and neutral complexes of the type (R3P(O)Ph2 (1a: R = Me; 1b: R = Ph, lc: R = o-Tol). 1a, b are obtained in high yield, but the yield of lc is lower owing to a side-reaction which leads to a different product: Ph2P(OH)-Au-P(O)Ph2 (2). The crystal structure of 1a was determined by a single-crystal X-ray diffraction study. The compounds is a monomer with a linear P-Au-P′ axis and the phosphane and phosphinite ligands in a staggered conformation. In solution (CHCl3, CH2Cl 2/) compounds 1a-c undergo a ligand redistribution, establishing equilibria that involve ionic isomers of the type [R3P)2Au]+ [Au-(P(O)Ph2)2]-, which are readily identified through their NMR data. The analogous reaction of (R3P)b AuMe with dimethylphosphite (MeO)2P(O)H gives methane and the corresponding dimethylphosphites of the type (R3P)AuP(O)(OMe)2 (3a: R = Me; 3b: R = Ph; 3c: R= o-Tol). The crystal structure of 3b has also been determined. It features a linear structure with an eclipsed conformation of the ligands. In polar solvents (CHCl3, methanol) there is again an eqilibrium between neutral and ionic isomers, the latter comprising bis(phosphane)gold cations [(R3P)2Au]+ and {Au[P(O)-(OMe)2]2)- anions, as confirmed by NMR spectroscopy and mass spectrometry.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300925
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    Regioselective Complexation of New Multiple Piperazine/Pyridine Ligands: Differentiation by 113Cd-NMR Spectroscopy (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1353-1359 
    Details
    ISSN: 0009-2940
    Keywords: 113Cd NMR ; Multidentate ligand ; Multinuclear metal complex ; Piperazine ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eleven novel piperazine containing open-chain ligands L1-L11 were designed to offer symmetrical and asymmetrical complexation sites for metal ions and were synthesized by repetitive synthetic method. The divergent use of aromatic bishalomethyl and mono-N-alkylated piperazine compounds as spaces led toa series of long (up to M. W. = 836) oligomeric multidentate N-ligands. Due to the lack of solid state methods for structure analysis, an NMR technique using 113 Cd nucleus as a probe in solution state was utilised. 113 Cd chemical shifts were observed to be dependend on the coordination site and similar coordination sites in different ligands gave characteristically similar 113 Cd chemical shifts. As a result 113 Cd-NMR spectroscopy proved to be an excellent tool to distinguish between the structures of the different complexation sites on a nearly quantitative level.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300929
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    Design of Self-Adapting N-Heteroaromatic Substituted Claw Ligands as E-/M+(E = P-Block Element, M = Main-Group Metal) Charge Spacers (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1365-1374 
    Details
    ISSN: 0009-2940
    Keywords: N ligands ; Chelates ; Coordination modes ; Ligand effects ; Structure-activity relationships ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monoanionic bi- and tridentate ligand systems emulating the structural features of the well-known poly(pyrazolyl)borates are created by bridging heteroaromatic rings with formally negatively charged p-block elements. Their properties and versatility are exemplified by their complexes with main group metals. Due to their N(σ)-donating and π-interacting ability, as well as the flexibility of the substituent bonding, these ligand systems have the potential to adapt both geometrically and electronically to the coordination requirements of the complexed metal. Within these complexes, the heteroaromatic substituents operate as charge spacers between the formally anionic center and the metal cation without encapsulating either site. This provides possible applications in the creation of reactive soft/hard bimetallic reagents, the realization of multinuclear arrays, and the design of preorganized CVD precursors, particularly en route to III/V-semiconducting thin films.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301004
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  • 59
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    Cyclic and Bicyclic Poly(phosphane)borane Cations (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1411-1416 
    Details
    ISSN: 0009-2940
    Keywords: Phosphane-boranes ; Boranes ; Phosphanes ; Umpolung, attempted ; Bond polarity ; Configuration determination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of (Me2S)BH2Br and (Me2S)BHBr2 with equimolar quantities of 1,2-bis(diphenylphosphanyl)ethene (1) or -benzene (2) lead to cyclic, cationic bis(phosphane)boranes [4[(1)BH2]+ Br-; 6: [(2)BH2]+ Br; 7: [(2)BHBr]+ Br-]. The Br counterions can be exchanged in metathesis reactions (e.g. with AgBF4 to afford 4a). The tritertiary phosphane bis[2-(diphenylphosphanyl)phenyl]phenyl-phosphane (3), reacts with (Me2S)BHBr2 to give bicyclic dicationic tris(phosphane)borane 8, [(3)BH]2+ Br-, which can be converted into the bis(hexafluorophosphate) 8a using NH4PF6. All compounds have been characterized by analytical and NMR-spectroscopic data. The crystal and molecular structures of 5 - 7 have been determined by single-crystal X-ray diffraction. The five-membered rings C2P2B have an envelope conformation and show no sign of electron delocalization. Attempts to deprotonate the B—H functions in 5 - 8 have not been successful. Clearly, the two (5 - 7) or three phosphonium centers (8) adjacent to the boron atom are not sufficient to induce an “umpolung” of the B—H group
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301009
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    Reactivity of the Heavier Group-13 Monochlorides [{CH(SiMe3)2}2AlCl], InCl, TlCl, and of the Elements Ga and Hg Towards the Unsupported Ni-Ni Bond of [{(η5-Cp)Ni(PEt3)}2]  -  A Straightforward Synthetic Approach to the Synthesis of Mixed Main-Group/Transition-Metal Clusters Containing Unsupported Metal-Metal BondsDedicated to Prof. Dr. G Hutter on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1433-1440 
    Details
    ISSN: 0009-2940
    Keywords: Metal - metal bonds ; Insertion reactions ; Group-13 monochlorides ; Main-group elements ; Nickel ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dinuclear compound [{(η5 - Cp)Ni(PEt3)}2] (1) containing an unbridged Ni-Ni bond reacts with the heavier group 13 monochlorides [{CH(SiMe3)2)2}AlIIICl], InCl, and TlCl by scission of the metal-metal bond. In the case of InCl and TlCl the chloro-bridged dimmers [{(η5-Cp)Ni(PEt3)2ECl2Ecl}2] (E = In 2, Tl 5) were formed. The Tl compound 5 is unstable and decomposes via disproportionation a and formation of the halogen-free Tl [III] compound [{(η5-Cp)Ni(PEt3)}3Tl] (6). 2 can be dehalogenated with activated magnesium to yield the halogen-free In [III] compund [{(η5-Cp}Ni(PEt3)}3In] (4). The Ga analogue of 4 and 6 [{(η5-Cp)Ni(PEt3)}3Ga] (7) is accessible by a conproportionation of 1 with Ga metal in refluxing THF. In contrast to InCl and TlCl the aluminium (III) monochloride [{CH(SiMe3)2}2AlCl] reacts with 1 by a ligand redistribution reaction and formation of the salt [{(η5-Cp)Ni(PEt3)2]+-[{CH(SiMe3)2]2AlCl]2-. (8). Elemental Hg or Mg amalgam show the same activity as elemental Ga towards 1 and insert into the Ni—Ni bond by forming the linear Hg-bridged complex [(n3-Cp)Ni(PEt3)]2Hg] (9). The molecular structures of 2, 4, 8, and 9 were determined by X-ray crystallography. The In atom in 4 has a distorted trigonal-planar configuration with the central In atom being surrounded by three [(n5-Cp)Ni(PEt3)] fragments. 4 represents the first Ni-In cluster containing exclusively unsupported In - Ni bonds, as well as the first carbonyl-free Ni - In cluster. On the basis of spectroscopic data the same structure is assigned to the Ga and Tl analogues of 4. The Ni—Hg—Ni arrangement in 9 is exactly linear, as determined by X-ray crystallography.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301013
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    Hydrocarbon-Bridged Complexes, XL. Polyene-Bridged Iridium(III), Palladium(II), and Platinum(II) Complexes of Schiff Bases from α,ω-Polyene Dialdehydes and α-Amino Acids or o-AminophenolDedicated to Professor Dieter Seebach on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1467-1473 
    Details
    ISSN: 0009-2940
    Keywords: Schiff bases ; Polyene dialdehydes ; α-Amino acids ; Pantamethylcyclopentadienyl complexes ; P ligands ; Iridium ; Palladium ; Platinum ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Schiff bases 1—11 were synthesized from α-amino acids or o-aminophenol and crocetindialdehyde, 2,7-dimethyloctatrienedial, terephthalaldehyde, or β,β′ -p-phenylendiacroleine. The reactions of these Schiff bases with chloro-bridged complexes [(R3P)(Cl)M(η-Cl)]2 (M = Pd, Pt) and [(C5Me5)(Cl)Ir(°Cl)]2 gave the dinuclear complexes 12-31.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301018
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    Enantioselective Catalysis. New Chiral Expanded Phosphanes Derived from Substituted Deltacyclenes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1495-1498 
    Details
    ISSN: 0009-2940
    Keywords: Deltacyclenes ; Deltacyclanes ; P-H addition reactions ; Chiral phosphanes ; Enantioselective catalysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The suitability of enantiomerically pure deltacyclenes as building blocks in the synthesis of expanded phosphanes was examined. Different substituted deltacyclenes were irradiated with diphenylphosphane and three bisphosphanyl derivatives. With these P—H addition reactions, new chiral deltacyclane-derived phosphorus ligands were synthesized. They were tested in the Rh-catalyzed asymmetric hydrogenation of (Z)-(ã)-N-acetamidocinnamic acid and in the Pd-catalyzed asymmetric allylation of 1,5-dimethylbarbituric acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301023
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    Masthead (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300101
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    Photochemical reactions of transition metal organyl complexes with olefins, 17Part 16: Ref.. Light-Induced [6+2] Cycloadditions of Dienes to Tricarbonyl(η6-1,3,5,7-cyclooctatetraene)chromium(0) (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 9-12 
    Details
    ISSN: 0009-2940
    Keywords: Chromium ; Chromium(0) complexes ; Cyclooctatetraene complexes ; Photochemistry ; Cycloadditions ; Photochemical [6+2] cycloadditions ; Dienes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tricarbonyl(η6-1,3,5,7-cyclooctatetraene)chromium (1) yields upon UV irradiation in ether at 233 K with 2,3-dimethyl-1,3-butadiene (2) or 2-methyl-1,3-butadiene (3) by [6+2] cycloadditions the correspondingly substituted tricarbonyl(η6-bicyclo[4.2.2]deca-2,4,7-triene)chromium complexes 4, 5a and 5b. With ammonium cerium(IV) nitrate the organic ligand of complex 4, 9-isopropenyl-9-methyl-bicyclo[4.2.2]-deca-2,4,7-triene (6) is liberated. The complexes 4, 5a and 5b were characterised by IR and NMR spectroscopy, the ligand 6 by NMR spectroscopy.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300103
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    A Structural Study of Selenobenzamides: Crystal Structures and Dynamic 13C NMR (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 49-54 
    Details
    ISSN: 0009-2940
    Keywords: 4-(p-Bromoselenobenzoyl)morpholine ; 4-[(p-(Dimethylamino)selenobenzoyl]morpholine ; Hindered rotation ; Hammett treatment ; Selenoamides ; Amides ; Selenium compounds ; Structure elucidation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solid-state structures of (p-bromoselenobenzoyl)morpholine (2a) and [p-(dimethylamino)selenobenzoyl]morpholine (2b) were determined by X-ray diffraction. Both molecules show a flat selenoamide group. The larger contribution of resonance stabilization by the aromatic ring carrying the p-dimethylamino substituent is reflected by the smaller interplanar angle Θ between the aromatic ring and the selenoamide group [53.3(1)° vs. 81.1(1)°] and by the shorter length of the C=Se bond [1.824(5) Å vs. 1.840(3) Å]. The Gibbs free energy of activation of C-N bond rotation (ΔG≠rot) of five p-substituted (selenobenzoyl)morpholines was determined by dynamic 13C NMR. The activation barriers were found to range from 61.6 kJ/mol (X = NNMe2) to 75.1 kJ/mol (X = H). The ΔG≠rot values of the corresponding (thiobenzoyl)morpholines were found to be from 3.2 kJ/mol (X = NMe2) to 5.0 kJ/mol (X = H) lower. In both cases, ΔG≠rot showed an excellent linear Hammett correlation with s̰+p.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300108
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    Synthesis and Characterization of Substituted Benzyl Zinc Derivatives - Molecular Structures of (tmeda) Li-CH (GeMe3)Ph, (tmeda)Zn(CH2Ph)2, (tmeda)Zn[CH(SiMe3)Ph]2, and (tmeda)Zn[CH(SiMe3)Ph]N(H)Si(SiMe3)3Dedicated to Professor Manfred Weidenbruch on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1499-1505 
    Details
    ISSN: 0009-2940
    Keywords: Lithium ; Zine ; Dibenzylzinc ; Tmeda complexes ; Heteroleptic alkylzinc amide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of lithium phenyl(trimethylsilyl)methanide with phenyl(trimethylsilyl)methylzinc chloride-tmeda in the presence of tmeda yields the addition product, a bis(tmeda)-lithium dialkylchlorozincate. The elimination of lithium chloride leads to the formation of a tmeda adduct of bis[phenyl-(trimethylsilyl)methyl]zinc. The metathesis reaction of phenyl(trimethylsilyl)methylzinc chloride-tmeda with lithium tris(trimethylsilyl)silylamide allows the isolation of the corresponding heteroleptic tmeda complex of an alkylzinc amide. The metalation of phenyl(trimethylstannyl)methane with butyllithium yields the transmetalation product benzyllithium. From the metathesis reaction of this lithium base with anhydrous zinc(II) chloride in the presence of tmeda, the tmeda adduct of dibenzylzinc crystallizes. The molecular structures of (tmeda)Li—CH(GeMe3)Ph, (tmeda)Zn(CH2Ph)2, (tmeda)Zn[CH(SiMe3)Ph]2, and (tmeda)Zn[CH(SiMe3)-Ph[N(H)Si(SiMe3)3 are reported. Whereas lithium bonds in an η3-fashion, the zinc atom forms a σ(Zn—C) bond. The extremely wide Zn—N—Si angle in (tmeda)Zn[CH(SiMe3)-Ph[N(H)Si(SiMe3)3 of 157° is remarkable.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301024
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    Unusual Dinuclear Hydridorhodium(III) Complexes Containing Bulky Phosphanyl(stibanyl)methanes as Chelating LigandsDedicated to Professor Luigi Venanzi on the occasion of his 70th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1529-1531 
    Details
    ISSN: 0009-2940
    Keywords: Rhodium ; Chelate complexes ; Hydrido complexes ; Bridging ligands ; P Ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mononuclear starting materials [Rh(η4-C8H12)(k2-P,Sb-iPr2PCH2SbR2)]PF6 (la, b) react with CF3CO2H in the presence of H2 to give the dinuclear hydridorhodium(II1) complexes [{RhH(k2-P,Sb-iPr2PCH2SbR2)]PF6 (2a, b) in almost quantitative yield. The X-ray crystal structural analysis of 2b (R = tBu) reveals a distorted octahedral geometry around the two metal centers with the two phosphanyl(stibanyl)methanes in a chelating and the two trifluoracetate ligands in a bridging coordination mode.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301028
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  • 68
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    X-ray and Solution Structure of Inosine 5' -Monophosphate Coordinated to (Ethylenediamine)palladium(II).  - the Importance of Intramolecular Hydrogen Bonding (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1551-1555 
    Details
    ISSN: 0009-2940
    Keywords: Antitumor agents ; Nucleotides ; Palladium ; Hydrogen bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The compound [Pd(en)(5′-IMP-N7)2].11 H2O, where 5′-IMP = inosine 5′-monophosphate, crystallizes in the tetragonal space group P4322 with the unit cell parameters: a = b = 12.060(5) and c = 28.510(5) Å, V = 4147(3) Å3, Z = 4. A head-to-tail orientation with A configuration is observed for the nucleotides which are coordinated through the N(7) positions such that d[Pd-N(7)] = 2.053(8) Å. The sugar moieties exhibit anti orientations toward the purine bases while their pukkers adopt C(3)′-endo conformation. The overall conformation about the phosphate backbone is gauche+. Intramolecular hydrogen bonding is observed between the phosphates and the NH groups of the en ligand with a donor-acceptor distance of 2.88 Å. The coordination mode of the solid-state structure is shown to be identical to that observed by 1H-NMR spectroscopy in solution under slightly acidic conditions, where the N (l) positions of the nucleotides are protonated. The results are discussed in reference to closely related systems reported in the literature with emphasis on the importance of hydrogen bonding in such complexes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301032
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    Synthetic and Structural Studies of 1-Sila-2,5-diaryltetrazenes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1579-1583 
    Details
    ISSN: 0009-2940
    Keywords: Silatetrazenes ; Nitrogen-silicon ring systems ; Bissilylamines ; Silicon-29 solid state NMR ; Aryl azides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction between aryl azides and lithiated aryl amines leads to tetrazenes 3 and 9 which contain a chain of four nitrogen atoms. Reaction with different halosilanes gives the cyclic silatetrazenes 10, 12, and 15 where substitutents on the silicon vary form alkyl to hydrogen and chlorine atoms. The structures of 10, 12, and 15 in the solid state are reported. Variation of the solvent and the Lewis acidity of the halosilane influence the ratio of silatetrazene to side products, bissilyated amines. These effects are studied for different halosilanes.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19971301105
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    Bildung und Charakterisierung des Dinatrium-tetraphosphendiids (tBu3Si)NaP-P=P-PNa(SitBu3) und seines Dimeren (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 135-140 
    Details
    ISSN: 0009-2940
    Keywords: Synthesis ; Phosphorus ; Supersilyloligophosphides ; Crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of P4 in THF or DME with 2 R*Na (R* = SitBu3) at -78°C leads quantitatively to deep red THF or DME adducts of R*NaP-P=P-PNaR* (3). According to 31P NMR, the P4 skeleton 3 is cis-configurated. On the other hand, reaction of P4 in TBME with 2 R*Na at -78°C leads quantitatively to (R*NaP)4 (4), a [2+2] cycloadduct of 3, the Na4P8 skeleton of which according to X-ray structure analysis forms a double cube with four P atoms in the second layer and two P and two Na atoms in alternating positions in the first and in the third layer (the Na atoms are coordinated with donors). By resolving the THF adduct 3 in TBME (the TBME adduct of 4 in THF) the compound 4 (the compound 3) is rapidly formed under reversal of the P-P=P-P configuration by way of [2+2] cycloaddition (by way of [2+2] cycloreversion). 3 and 4 are sensitive to oxidation and to protolysis. With TCNE, 3 is oxidized to R*2P4 (bicyclic P4 skeleton), with CF3SO3H, 3 may be transformed into R*3P5Na2 X 4 THF or in (R*P3)3 and R*PH2.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300123
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    Cyclopentadienyl Ring Metathesis with Organocalcium and Organopotassium Compounds (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 155-159 
    Details
    ISSN: 0009-2940
    Keywords: Cyclopentadienes ; Metathesis ; Potassium ; Calcium ; Main-group elements ; Sandwich complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclopentadienyl ring metathesis occurs between [Ca(C5Me5)2] and [Ln(C5H5)3] complexes in toluene to generate the mixed ring compounds [Ln(C5Me5)2(C2H5)] (Ln=1-La, 1-Nd). 1-Nd has been characterized with X-ray diffraction as a sterically crowded monomer. Only one ring is exchanged between [Ca(C5Me5)2(thf)x] and [La(C5H5)3(thf)x] in toluene to yield [La(C5Me5)C5H5)2 (thf)] (2). In reaction with [M(C5H5)2] (M=Sn, Pb, Mn), [Ca(C5M5)2(thf)x] yields the corresponding [M(C5Me5)2] complexes. K[C5Me5] reacts with [La(C5H5)3(thf)], [Sn(C5H5)2] and [Pb[C5H5)2] in toluene to yield the ring-exchanged products 2, [Sn(C5Me5)2], and [Pb(C5Me5)2], respectively.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300204
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    Sterically Shielded Titanocene Enolates - Synthesis, Structure and Their Exceptional Stability towards Hydrolysis (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 195-199 
    Details
    ISSN: 0009-2940
    Keywords: Titanium ; Enolates ; Kinetics ; Enols ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of various sterically congested sodium enolates, generated by quantitative deprotonation of stable enols (of diphenylacetaldehyde in the case of 5), with dichlorotitanocene afforded a series of novel titanium enolates 1-5. The crystal structure of 1 could be determined. Due to the considerable steric shielding of the β,β-diaryl moiety, all the titanium enolates exhibit an oustanding stability towards hydrolysis, which increases with the higher steric demand of the substitutents at the C-C double bond. The kinetics of the hydrolysis, which is pseudo-first-order in THF/water (1 : 1) and acetonitrile/water (1 : 1), was investigated by UV spectroscopy. The pseudo-first-order rate constants measured in these solvent mixtures are in the range 6.4 · 10-4 s-1 〈 k1 〈 1.1 · 10-3 s-1. For comparison, the hydrolysis of 6, which should exhibit the usual sensitivity of titanium enolates towards hydrolysis, is about 1000 times faster.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300209
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    (Triphenylphosphane)gold(I) Scrambling in a Hexanuclear Complex of Phenylene-1,2-bis(phosphane) (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 217-219 
    Details
    ISSN: 0009-2940
    Keywords: Gold compounds ; (Phosphane)gold(I) complexes ; Clusters ; P Ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phenylene-1,2-bis(phosphane) reacts with two mole-equivalents of tris[(triphenylphosphane)gold(I)]oxonium tetrafluoroborate in dichloromethane at -78°C to give high yields of a hexanuclear complex {C6H4]P(AuPPh3)3]2}2+ · 2 BF-4 (1). The variable-temperature 31P{1H}-NMR spectra of the product in CD2Cl2 at - 80°C are compatible with a static structure featuring three Ph3PAu units associated with each of the two C6H4P2 phosphide functions, as derived from a clear doublet/quartet pattern. At 50°C in CDCl3, however, there is rapid intramolecular scrambling of these Ph3PAu units, which gives rise to a triplet/septet pattern with the J(P,P) value reduced to exactly one half of the value at the low temperature limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300212
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    Synthesis and Properties of New Mixed-Halide Derivatives of Iron-Sulfide Dimers-Crystal Structure of (Et4N)2[Fe2S2Cl2Br2] (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 235-239 
    Details
    ISSN: 0009-2940
    Keywords: Iron-sulfur cluster ; Mixed halide ligands ; Magnetic properties ; Clusters ; Iron compounds ; Sulfur compounds ; Halogen compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterization of the new mixed-halide clusters (Et4N)2[Fe2S2Cl4-nBrn] (n=2, 3), together with an improved synthesis of (Et4N)2[Fe2S2Br4] and the crystal and molecular structure of (Et4N)2[F2S2Cl2Br2], are reported here. The structure consists of [Fe2S2Cl2Br2] dianions, with a pseudo-tetrahedral symmetry around each iron atom. A disorder problem precludes precise identification of the locations of the chloride and bromide ligands. A syn (or anti) conformation is however considered to be most likely, for steric hindrance reasons and on the basis of Mössbauer data. The Mössbauer, magnetic susceptibility, cyclic voltammetry and UV/Vis properties of the new clusters remain similar to those of the parent single-type halide clusters. These new clusters are interesting precursors for complexes with mixed thiolate and non-thiolate coordination at the iron sites.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300216
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    Synthesis, Structure, and Reactivity of Tetrakis(O,O-phosphorus)-Bridged Calix[4]resorcinols and Their Derivatives (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1715-1720 
    Details
    ISSN: 0009-2940
    Keywords: Calix[4]resorcinols ; Dioxaphosphocins ; Supramolecular chemistry ; Solid-state NMR spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterisation of the reactive tetrakis (O,O-phosphorus)-Bridged calix[4]resorcinols 3 and 4 is described. Because of its poor solubility in common organic solvents, a solid-state NMR investigation of 3 (1H, 13C, 31P) was conducted. Reaction of 3 with MeMgl, Me3 SiMNe2, and HNMe2 furnished the η3γ3P-substituted cavitands 5 and 6. Oxidative addition reactions of 6 with the (H2N)2C(=O)/H2O2 (1:1) adduct, tetrachloro-o-benzoquinone (TOB), and hexafluoroacetone (HFA) led to the η4γ5P derivative 7, and to the η5γ5P derivatives 8 and 9. An X-ray crystal-structure determination of the tetrakis(O,O-phosphorus)-bridged calix[4]resorcinol 4 has been conduced. The framework displays the cone conformation; the chlorine atoms are directed inwards.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301124
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    Tetra(amino)methanes: Implications of Their Structure and Reactivity Pattern for Hypothetical Carbon Nitride FrameworksDedicated to Professor George A. Olah. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1739-1744 
    Details
    ISSN: 0009-2940
    Keywords: Carbon nitride ; Tetra(amino)methanes ; Guanidinium salts ; Amination ; Conformation analysis ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Because of their possible role as model compounds for the structural units of carbon nitride C3N4, the preparation, structural chemistry, and some representative reactions of tetra(amino)methanes have been (re)investigated. In the crystal, C(NMe2)4 (1) has a molecular geometry close to D2a symmetry as proposed by theoretical calculations using state-of-the-art density functional methods. The coordination of the central carbon atom is distorted tetrahedral and the configuration of the nitrogen atoms is strongly pyramidal, as opposed to almost planar in the tetra(amino)silanes. Tetra(pyrrolidinyl)methane has a similar core structure, with all heterocyclic substituents in an envelop conformation flexible in solution. Tetra(piperidinyl)methane is more rigid in solution, owing to a more congested structure, with much higher inversion barriers for the six-membered rings. Hydrolysis of 1 leads to MezNH and hexamethylguanidinium hydroxide, and treatment of 1 with HAuCl4(aq) affords crystalline [C(NMe2)3]4 AuCl4- the structure of which has also been determined. Compound 1 is a strong nucleophile and can be used as an aminating agent, converting e.g. halosilanes into dimethylaminosilanes, with the guanidinium cation as the leaving group. The experimental results are discussed in the light of recent predictions regarding bulk carbon nitrides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301206
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    Halogenation of 1-Ethoxy-1-oxophosphindolin-3-one, a Potential Phosphaindigo Precursor (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1765-1770 
    Details
    ISSN: 0009-2940
    Keywords: Phosphinic acid ; Phosphaindole bromination and chlorination ; Layer structure ; Hydrogen bonds ; Bromine-bromine interaction ; Phosphorus heterocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bromination of 1-ethoxy-1-oxophosphindolin-3-one (1) with two equivalents oi bromine occurs with elimination of hydrogen bromide and ethyl bromide, providing 2,2-di- bromo-1-hydroxy-1-oxophosphindolin-3-one (4) in high yield. In the presence of triethylamine this process leads to 2,2-dibromo-1-ethoxy-1-Oxophosphindolin-3-one (3) instead. Triethylamine deprotonates 4, providing the solid triethylammonium salt 5. Silylation of 4 with chlorotrimethylsilane leads to the trimethylsilyl ester 6. Monobromination in a two-phase reaction allows the isolation of a mixture of isomers of 2-bromo-1-ethoxy-1-oxophosphindolin-3-one (2a, b). Chlorination with chlorine furnishes 2,2-dichloro-1-ethoxy-1-oxo-phosphindolin-3-one (7). The new compounds 2-7 were characterized analytically and spectroscopically (EI-MS, 1H, 13C and 31P NMR). The crystal structure of acid 4 was determined by X-ray diffraction. Solid 4 consists of aryl stacks connected by chains of P—OH…O==P hydrogen bonds and secondary Br…Br contacts.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301210
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    Kinetics and Mechanism of Substitution Reactions of cis-[PtMe2(dmso)2] with Pyridine (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1791-1799 
    Details
    ISSN: 0009-2940
    Keywords: Platinum substitution ; Metal-carbon bonds ; trans-Labilization ; Kinetics ; Activation parameters ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The substitution reactions of cis-[PtMe,(dmso),] with pyridine (py) to produce cis-[PtMe2py2] in toluene proceeds in two steps. In the absence of added dimethylsulfoxide (dmso), these steps can not be separated due to the rate constants being very similar. In the presence of added dmso, the rate of the first step, the formation of the monopyridine complex is retarded, which is indicative of a dissociative mechanism. A parallel associative reaction path with pyridine could also be observed. This pathway is independent of the concentration of added dmso. Above a 40-fold excess of dmso, the dissociative pathway is suppressed and only the associative reaction occurs. A plot of Kobs vs the pyridine concentration for this pathway is linear at low [py], but shows a saturation at high [py]. This suggests that the reaction occurs via the formation of a precursor-complex, for which the formation constant was found to be 0.32 · 0.03 M-1. The volume of activation at a high pyridine concentration is -11.4 · 0.8 cm3 mol-1, which indicates that the ligand interchange process is of the associative type. The second step, the formation of the bispyridine complex, can clearly be separated from the first reaction step. This step occurs via a dissociative mechanism, as demonstrated by the decrease in kobs with increasing pyridine concentration. The dissociation of dmso was characterized by a rate constant of (8.1 · 0.9).10-45-1 at 25°C, ·H = 116 ·9 kJ mol-1 and AS. = 86 · 29 JK-1 mol-1. At higher pyridine concentrations evidence for a parallel associative reaction was found, for which the rate constant is (1.3 · 0.2).10-3 M-1S-1 25°C. The results are discussed in reference to available literature data.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301214
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    Synthesis and Properties of Me2Ge-Bridged Arenes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 421-424 
    Details
    ISSN: 0009-2940
    Keywords: Macrocycles ; Germanium ; UV/Vis spectroscopy ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Linear and cyclic oligomers of Me2Ge-bridged π-systems have been obtained by the reaction of carbo- and heterocyclic anions and dianions with Me2GeCl2. The spectroscopic properties of the new compounds are compared with analogous carbon- and Me2Si-bridged π-systems.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/cber.19971300318
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  • 80
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    P/O Ligand Systems: Synthesis, Reactivity, and Structure of Tertiary o-Phosphanylphenol Derivatives (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 431-431 
    Details
    ISSN: 0009-2940
    Keywords: o-Phosphanylphenols ; P,O hybrid ligands ; P asymmetry ; C,O-dilithium reagents ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300320
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  • 81
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    Masthead (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997) 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300401
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  • 82
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    Molybdenum-Catalysed and -Mediated Cycloaddition Reactions: Efficient Synthesis of Complex Products from 1-Oxa-1,3-dienes and Cyclotrienes or -tetraenes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 453-462 
    Details
    ISSN: 0009-2940
    Keywords: Cycloadditions ; Catalysis ; 1-Oxa-1,3-dienes ; Molybdenum ; stereoselectivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molybdenum-mediated [6 + 2]-cycloaddition reactions of unsaturated ketones to cyclotri- or -tetraenes, e.g. cyclohepta-1,3,5-triene or cyclooctatetraene, proceed under very mild conditions, in high yields and with excellent stereoselectivity starting from the appropriate dicarbonylbis[π4-(1-oxa-1,3-diene)]molybdenum complexes. The stereochemistry of the product arising from the reaction of dicarbonylbis[π4-(5-methylhex-3-en-2-one)]molybdenum with cyclohepta-1,3,5-triene allows one to deduce a stepwise mechanism for this addition. The reactants are fused, as would be expected from an exo-type approach, thus indicating an intermolecular attack of the cycloheptatriene. Tungsten oxadiene complexes are effective in analogous reactions at somewhat reduced reaction rates. Catalytic cycloadditions are observed in several cases when 1-5 mol% of the highly reactive dicarbonylbis[π4-(R-(+)-pinocarvone)]molybdenum is employed as the catalyst. Cycloadducts are formed diastereospecifically in most cases. When cyclooctatrienes are employed as reactants, a sequence of electrocyclization of the triene and subsequent [4 + 2]-cycloadditon occurs with high selectivity and efficiency, leading to a pentacyclic ketone. The product structure reveals an endo-type approach of the polyene in this case.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300404
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  • 83
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    Tris-Chelating Oxygen Ligands: New Synthetic Routes to Sterically Demanding Ligands (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1223-1229 
    Details
    ISSN: 0009-2940
    Keywords: Tripodal ligands ; O ligands ; Cabalticenium cation ; Sodium coordination ; Ligand profile ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The lithium and sodium compounds A[P(O)R2] (A+ = Li+, Na+; R = OPh, OiPr) have been prepared in situ from Hp(O)R2 and butyllithium or sodium hydride. They react with the cyclopentadienyl complexes [(C5H5)MI2(CO)] (M = Co, Rh), [(C5Me5)CoCl2]2, and [(C5H5)CoI2]n to yield alkali metal salts AL of tridentate oxygen ligands (A+ = Li+, Na+; L- = [(C5R′5]M{P(O)R2}3]-, R′ = H, Me; M = Co, Rh; R = OPh, OiPr) (2). For the ligand LCo, OPh = [(C5H5)-Co{P(O)(OPh)2}3]-, an alternative synthesis has been developed, starting from [(C5H5)2Co]PF6. The structure of the sodium salt NaLCo, OPh (2d) has been determined by X-ray diffraction. The ligand LCo, Oph-, with a cone angle TH of about 200°, completely blocks one half of the coordination sphere around the sodium centre. The ligand profile has been calculated to allow appraisal of the angular encumbrance of the ligand.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971300909
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  • 84
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    Synthesis, Redox Chemistry, and Mixed-Valence Phenomena of Cyanide-Bridged Dinuclear Organometallic Complexes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1241-1252 
    Details
    ISSN: 0009-2940
    Keywords: Organometallic complexes ; Cyanide bridges ; Structure elucidation ; Isomerizations ; Oxidation ; Mixed valent compounds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 21 new organometallic complexes of the type M-Cn-M′ containing the building blocks M, M′ = (CO)5Cr, (CO)5Mo, (CO)5W, Cp(CO)2Mn, Cp(CO)2Fe, Cp(CO)(CN)Fe, Cp(dppe)Fe, Cp(PPh3)2Ru, Cp(PPh3)Ni, and (PPh3)2Ag were obtained from the reagents M-Cn and M-X (X = leaving group). Among them are five pairs of linkage isomers M-CN-M′/M-NC-M′. Structure determinations of (CO)5Cr-CN-M′ with M′ = Fe(dppe)Cp, Ni(PPh3)Cp, Ag(PPh3)2 and of (CO)5Cr-NC-Fe(dppe)Cp have proved their identity and the linkage isomerism. Systematic variations of the v(CN) and v(CO) IR bands allow as assessment of the relative electron pair acceptor strengths of the building blocks M and M′ and a reliable identification of the individual linkage isomers. All dinuclear complexes are redox-active, showing at lease one reversible oxidation. The redox potentials are characteristically dependent upon the nature of the building blocks M and M′ and upon the orientation of the cyanide link (CN vs. NC), 6 oxidized complexes of the type [M-Cn-Fe(dppe)Cp]+ were prepared chemically and isolated as PF6 or BF4salts. The molecular structure of [(CO)5Cr-CN-Fe(dppe)Cp]BF4 is not significantly different from those of the corresponding neutral Cr-CN-Fe or Cr-NC-Fe complexes. Upon oxidation the v(CN) band of the complexes shifts to lower wavenumbers and becomes much more intense. The oxidized complexes show the paramagnetism due to one unpaired electron. They give rise to very intense metal-to metal charge-transfer bands in the near infrared region whose position was found to be characteristically dependent on solvent polarity of [(CO)5Cr-CN-Fe(dppe)Cp]BF4. A semiquantitative treatment of the optical and electrochemical measurements shows that the electron delocalization and metal-metal interaction in the oxidized dinuclear complexes is significant and that they belong to the class-II mixed-valence systems.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300912
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  • 85
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    A Density Functional Study of the Systems [MH3(PMe3)4]+ (M = FE, RU, OS) (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1273-1277 
    Details
    ISSN: 0009-2940
    Keywords: Transition metal ; Complexes of the iron triad ; Density functional calculations ; Relativistic effects ; Hydrido complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structures and relative energies of various isomers of [FeH3(PMe3)4)+ (1), [RuH3(PMe3)4]. (2) and [OsH3(PMe3)4]. (3) have been studies by density functional theory. The stereoisomers considered are derived from a tetrahedral (T), square planar (P), and C2v-butterfly (C) arrangement of the phosphane ligands. For the latter two, classical trihydride (I) and nonclassical hydride/dihydrogen (II) geometries have been considered 1 and 2 prefer coordination mode II, whereas 3 favours coordination mode I. This trend is explained by relativistic effects. For Fe and Os, the C and T type structures are preferred over a P geometry. for Ru, the C and P structures are close in energy, and the T arrangement represents the highest energy isomer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300916
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  • 86
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    Transition-Metal-Substituted Acylphosphanes and Phosphaalkenes, 35 Unprecedented Coupling of a Transition-Metal Carbyne and a Methylene Phosphane Moiety - Structure of [Tp'(CO)2W=CP=C(NEt2)2] [Tp = HB (3,5-Me2HC3N2)3] (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1305-1308 
    Details
    ISSN: 0009-2940
    Keywords: Carbyne complexes ; Phosphaalkenes ; Molybdenum ; Tungsten ; . interactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Condensation of [Tp](CO)2 Mčl] [1: M = Mo; 2: W; Tp] HB (3,5-Me2HC2N2)3] with the inverse phosphaalkenes Me3 Sip=C(NR2)2 (3a: R = Me; 3b: Et) affords the novel phosphaalkenyl carbyne complexes [Tp](CO)2M.C-P=C(NR2)2] (a, b) (M = Mo; R = Me, Et) and 5a, b (M = W; R = Me, Et), which have been characterized by IR, 1H-, 13C- and 31P-NMR spectroscopy. In additon, the molecular structure of 5 has been elucidated by a single-crystal X-ray structure determination.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300920
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  • 87
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    Palladium  -  Catalyzed Reactions, 1 Palladium-Catalyzed Enantioselective Hydrophenylation and Hydrohetarylation of Bicyclo[2.2.1]Hept-2-ene: Influence of the Chiral Ligand, the Leaving Group, and the Solvent (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1327-1331 
    Details
    ISSN: 0009-2940
    Keywords: Asymmetric catalysis ; Hydroarylation ; Palladium ; P-N ligands ; Heterocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of optically active biaryl bisphosphanes 10-12, a diphenylphosphanylphenyloxazoline 8, and a (β-N-sulfonyl-aminomethyl)bisdiphenylphosphane 7 as ligands in the Pd-catalyzed Heck-type hydroarylation of norbornene (1) with phenyl 2 and various hetaryl derivaties 3-5 leads exclusively to the formation of exo-2(het)arylnorbornanes 6 with asymmetric inductions of up to 86.4% ee. In addition to an investigation into the effects of different chiral ligands, a systematic study has been made of the influence of various (het)aryl compounds, leaving groups, and solvents on the chemical and optical yields of this reductive arylation.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300924
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  • 88
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    Synthesis and Structural Characterization of Mixed-Ligand Oxorhenium(V) Complexes Containing Bidentate Dithioethers and Monothiolato Ligands (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1343-1347 
    Details
    ISSN: 0009-2940
    Keywords: Rhenium ; Technetium ; Radiop[pharmaceuticals ; Mixed-ligand complexes ; sulfur ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Neutral oxorhenium(V) complexes with dithioether ligands of the general formula [ReOX3(RS[CH2]2SR)], × = Cl, Br, R = nBu, Et, Bzl were synthesized. Ammonium perrhenate reacts in concentrated hydrochloric acid with dithiaalkanes (RS[CH2]2SR, R =nBu, Et, Bz) dissolved in glacial acetic acid to give octahedral complexes of the type [ReOCl3(RS[CH2]2SR)] (1a-c). In concentrated hydrobromic acid, nBu-S(Ch2)2S-nBu leads to the corresponding tribromo complexes (2). The X-ray structure of shows a distorted octahedron with facial coordination of the bromide ligands. The sulfur atoms are cis coordinated to the terminal oxygen. Dissolution o f1a (R = nBu) in methanol leads to the substitution of the chloride trans to the oxo ligand by a meth oxy group. The resultant complex [ReOCl2(MeO) (nBu-S[CHL2]2S-nBu)] (3) is stable and can be isolated from methanolic solution, but changes to the μ-oxo-bridged dirhenium complex μ-oxobis[dichloro(5,6-dithiadidodecane)oxorhenium(V)] (4) when dissolved in other organic solvents. 1a reacts with an excess of benzenethiol by substitution of two chlorides to give the mixed-ligand complex bis(benzenethiolate)chloro(5,8-dithiadodecane)oxorhenium(V) (5a). The related 4-methylbenzenethiolato complex 5b was synthesized starting from the μ-oxo complex 4. X-ray crystal structure determination of 5b shows the equatorial arrangement of the sulfur atoms. The trans position to the oxygen atom is occupied by a chloride ion.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300927
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  • 89
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    Editorial (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. i 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301003
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  • 90
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    Diastereoselectivity in the Reaction of RCH2C[CH2P (Ar)(Lr)]3 with Electrophiles: Enhancement of Diastereoselective Control by η3-Coordination in {RCH2C[CH2P(Ar)(Li)3}Mo(Co)3 (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1379-1392 
    Details
    ISSN: 0009-2940
    Keywords: Chiral tripod ligands ; Tripod Mo(CO)3 compounds ; Diastereoselective synthesis ; Separation of diastereomers ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Following a procedure developed for H3CC[CH2P(Ph)2]3 (1a) as the starting compound, various tripod ligands RCH2C[CH2P(Ar)2]3 (1) have been transformed into the trilithiotriphosphides RCH2C[CH2P(Ar)(Li)]3 with various electrophiles R′  -  Hal leads to the two diastereomers of RCH2C[CH2P-(Ar)(R)]3 (6) with an (RRR/SSS : RRS/SSR) ratio close to the statistical value of 1:3, except when Ar=Ph and R′=Bzl, where the RRS/SSR diastereomer is obtained almost exclusively. In contrast, the reaction of [RCH2C[CH2P(Ar)(Li)[3]-Mo(CO)3 (4) with electrophiles R′  -  Hal tends to favour the formation of the homochiral RRR/SSS diastereomers. The triphosphide coordination compounds 4 are available by two different routes: either the complexes (RCH2C[CH2P-(Ar)(H)]3Mo(CO)3, obtained from 2 and (CH3CN)3Mo(CO)3, are deprotonated by MeLi, or the trilithiotriphosphides RCH2C[CH2P(Ar)(Li)]3 are reacted with (CH3CN)3Mo(CO)3 to produce 4 in high yields. The ration in which the two diastereomeric forms of 5 are obtained depends on the nature of the electrophile: the greatest diastereomeric discrimination is obtained for Ar=Ph, R=Ph, R′=Bzl, where the homochiral relative to the RRS/SSR pair. Two-dimensional NMR spectra and simulations of one-dimensional spectra are used to ascertain the diastereomeric excess in each case. X-ray analyses of three compounds of type 5 (5d, Ar=Ph, R=H, R′=Ph, R′=Bzl) indicate the remarkable conformational stability of the tripod metal scaffolding, with the conformations observed for these three compounds in three different solid-state environments being closely similar, even with respect to the torsional arrangement of the phosphorus-bound benzyl groups.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301006
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  • 91
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    Gold(1) Complexes of Ketiminophosphanes and -phosphane Sulfides (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1423-1426 
    Details
    ISSN: 0009-2940
    Keywords: Gold ; Gold(I) complexes ; (Imine)gold(I)complexes ; Ketiminophosphanes ; (Ketiminophosphane)gold(I) complexes ; Ketiminophosphane sulfides ; (Ketiminophosphanesulfide)gold(I) complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of chloro(dimethyl sulfide)gold(I) with equivalent quantities of the ketiminophosphane diphenyl(diphenylmethyleneamino)phosphane (1a) or its sulfide (1aS) lead to high yields of stable, crystalline 1 : 1 complexes with AuCl units attached to the phosphorus and sulfur atom, respectively. Tris(diphenylmethyleneamino)phosphane (1c) gives the related complex (Ph2C=N)3PAuCl with the gold atom also selectively P-bound. Bis(diphenylmethyleneamino)phenyl-phosphane (1b) could not be used because of its limited stability. Single-crystal X-ray diffraction studies have shown that there is no auxiliary coordination of the metal center by the imino functions of the ligands. The geometry of the P/S—Au—Cl moieties deviates only very slightly from linearity. The angle at the sulfur atom in (Ph2C=N)Ph2PSAuCl is very small [94.30(3)°], but despite of the resulting rather open coordination there are no discernible intra- or intermolecular contacts in the lattice. Such contacts are also absent with (Ph2C=N)Ph2PAuCl and (Ph2C=N)3PAuCl owing to the bulk of the ligands. The 1 : 1 complexes do not react with an excess of (Me2S)AuCl. This finding, and the molecular structures of the 1 : 1 complexes, show very consistently that both phosphane and sulfide donors are far superior as ligands for gold(I) as compared to ketimine donor molecules.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301011
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    Pyrazolate-Based Oligonuclear Copper and Silver Complexes with N/S Coordination SpheresDedicated to Prof. Dr. Gottfried Huttner on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1441-1447 
    Details
    ISSN: 0009-2940
    Keywords: Pyrazolate complexes ; Bridging ligands ; Copper ; Silver ; N,S-Donor Ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of pyrazole-based potential ligands bearing thioether substituents in 3- and 5-positions of the heterocycle was synthesized [3,5-bis(RSCH2)-pyzH R=Ph (1aH), PhCH2 (1bH), iPr (1cH), tBu (1dH)]. These ligands afford oligonuclear Cu1 and Ag1 coordination compounds [LCu]x (2a-c, L = 1a - c) and [LAg]x (3a-d, L = 1a-d), respectively. The single crystal X-ray analysis of 3c shows the presence of trimeric planar arrays of N,N′-bridging pyrazolates and linear coordinated silver ions, with each two of the trinuclear moieties being linked by two unsupported short intermolecular Ag…Ag contacts [3.041(1) Å]. Molecular-weight determinations for 2a (THF) and 3c (toluene) indicate that hexanuclear entities are preserved in solution. Starting from 1bH the CuII complex [(1b)2Cu2](BF4)2 (4) was synthesized. According to an X-ray crystal structure analysis it consists of dinuclear molecules with two bridging pyrazolates, distorted square planar N2S2 coordination spheres for Cu11 and an axially bridging tetrafluoroborate. Magnetic susceptibility data reveal an antiferromagnetic exchange (J = -206 cm-1) that is among the highest found for doubly pyrazolate bridged dicopper(II) complexes, which is rationalized on the basis of the rather symmetric dinuclear core of 4. The irreversibility of the electrochemical reduction and oxidation processes for the CuII and CuI compounds, respectively, is explained by the inability of the respective coordination framework to adapt to different geometric preferences.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cber.19971301014
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    Hydrocarbon-Bridged Metal Complexes, XLI. Addition of Aniline Tricarbonyl Chromium Complexes to the Cyclohexadienyl Ligand of (μ5-C6H7)M(CO)3+ (M = Fe, Ru)Dedicated to Professor Hanns-Peter Boehm on the occasion of his 70th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1475-1477 
    Details
    ISSN: 0009-2940
    Keywords: Iron ; Ruthenium ; Chromium ; Carbonyl complexes ; N-(2,4-Cyclohexadienyl)aniline ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The addition of aniline tricarbonyl chromium complexes (η6-C6H4(R)NHR1)Cr(CO)3 (R=H, CH3; R1=H, CH3) to [(n5-C6H7)M(CO)3]+ (M=Fe, Ru) gives the heterobimetallic ligand-bridged complexes (OC)3Cr(n6-C6H4(R)N(R1)C6H7-n4)M(CO)3. The structure of (OC)3Cr(n6-C6H4(CH3)N(H)-C6H7-n4)Ru(CO)3 has been determined by X-ray diffraction.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301019
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  • 94
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    New Phosphorus Heterocycles by Rearrangement of a [1,4-Bis(trimethylsilyl) η8-cyclooctatetraene-1,3,5-triphospha-7-hafnanorbornadiene ComplexDedicated to Professor C. G Kreiter on the occasion o f his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1491-1494 
    Details
    ISSN: 0009-2940
    Keywords: Phosphorus heterocycles ; Phosphaalkynes ; Triphospha Dewar benzenes ; Triphosphacyclobutadiene ; 1,4-Bis(trimethylsilyl)-η8-cyclooctatrienehafnium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [1,4-Bis(trimethylsilyl)-n8-cyclooctatetraene]-2, 4, 6-tri-tert-butyl-1, 3, 5-triphospha-7-hafnanorbornadiene (3) rearranges nearly quantitatively to the corresponding 3,5,6-tri-tert-butyl-1,2,4-triphospha-7-hafnanorbornadiene complex 5 upon heating at 70°C. Treatment of complex 5 with trimethylphosphane at 50°C induces the displacement of di-tert-butylacetylene to give the new (n4-triphosphacyclobutadiene)hafnium complex 7, the crystalstructure of which has been determined by X-ray analysis. From complex 5 3,5,6,-tri-tert-butyl-1,2,4-triphospha Dewar benzene (6) can be synthesized by a redox reaction with hexachloroethane.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301022
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    Dirhenium Complexes with S2CPR3 Bridges Donating Four and Eight Electrons  -  X-ray Structures of [Re2(CO)8{μ-η1;η1-S2CPCy3}] and {Re2(CO)6{μ-η3;-S2CPCy3}] and [Re2(CO)6{μ-η2; η3-S2CPCy3}] (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1507-1511 
    Details
    ISSN: 0009-2940
    Keywords: 1,1-Dithiolate ; Rhenium ; Carbonyl complexes ; Bridging ligands ; Bimetallic complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of fac-[Re(CO)3(S2CPR3)Br] with [Rc(CO)5]- affords the dinuclear octacarbonyl compounds [Re2(CO)8(μ-S2CPR3)] (3a—b), which have been isolated and characterized by spectroscopic methods. An X-ray crystal-structure determination of the derivative 3a (R=Cy) shows that the S2CPCY3 ligand acts as an η1(S);η1(S′) bridge donating two electrons to each metal atom of a symmetrical (CO)4Re—Re(CO)4 unit. This unit is presumably formed through a concerted process involving carbonyl/sulfur exchange in the nonsymmetrical octacarbonyl (CO)3(S2CPR3)Re—Re(CO)5 generated after the coupling of the bromo derivative with the carbonyl anion. Complexes 3a—b can be obtained more directly by adding S2CPR3 to [Re2(CO)8(μ-H)(μ-CH=CHnBu)], which is formed by irradiation of Re2(CO)10 with 1-hexene. Hydride addition to the central carbon atom of the S2CPR3 ligand of 3a-b occurs with loss of PR3, to give the anion [Re2(CO)8(μ-S2CH)]- which may be isolated as a salt with the PPN+ cation. The octacarbonyl compounds 3a-b can be converted into hexacarbonyl complexes [Re2(CO)6(μ-S2CPR3)] (5a-b) by heating in toluene or octane at reflux temperature. According to an X-ray crystal-structure determination of the derivative 5a (R=Cy), the loss of one carbonyl ligand from each rhenium atom is accompanied by the rearrangement of the S2CPR3 ligand which changes its bonding mode from η1(S);η1(S′) donating four electrons to η3(S,C,S′);η2(S,S′) donating eight electrons.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301025
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  • 96
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    Interactions in Molecular Crystals, 118. The Sodium(benzo-15-crown-5) Salt of 2, 6-Di(tert-butyl)-4-methylphenol, a Sodium Phenolate with an Extremely Short Na+…O- Distance: Structure and Density Functional Calculations (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1533-1537 
    Details
    ISSN: 0009-2940
    Keywords: 2,4,6-Trialkylphenol deprotonation ; Sodium/benzo-15-crown-5 solvation ; Crystal structure ; Density functional calculation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of crystals, isolated in low yield, from the attempted metallation of diphenylmethane in tetrahydrofuran solution containing benzo-15-crown-5 at a sodium metal mirror is determined, surprisingly, to be the sodium (benzo-15-crown) salt of 2,6-di(tert-butyl)-4-methylphenol, an antioxidative stabilizer to prevent ether peroxide formation. The structure of the solvent-shared contact ion pair (monoclinic P21/n, Z = 4, R1 = 0.06) proves a strong Na+…O- interaction at the extremely short distance of only 216 pm, a sixfold O-coordination of the Na+ cation in a pentagonal pyramid, and a hemispherical distortion of the crown ether. Density functional calculations at the B3LYP/6-31G* level, based on the structural data, reproduce, within a one-dimensional hypersurface approach, the rather short Na+…O- distance, and predict Mulliken charges of +0.32 for Na′ and -0.71 for 0-, as well as a considerable polarization of the trialkyl phenolate anion.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301029
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  • 97
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    Palladacycles as Reactive IntermediatesDedicated to Prof. Dr. Dietrich Döpp on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1567-1578 
    Details
    ISSN: 0009-2940
    Keywords: Metallacycles ; Palladium catalysis ; Domino reactions ; Polycyclic ring systems ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Palladacycles are discussed as the key intermediates of some important preparative ring forming reactions; their reactivity depends strongly on the ring size. The existence of 5-membered palladacycles, and even 4-membered palladacycles, is now firmly established, whereas the knowledge of 6-membered and larger palladacycles is based mainly on mechanistic considerations. The role of 5-membered palladacycles as catalysts is described briefly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301104
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  • 98
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    Olefin Carbonylation Catalysis with Cationic Palladium Complexes: Selectivity and Possible Intermediates (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1557-1565 
    Details
    ISSN: 0009-2940
    Keywords: Carbonylations ; Alkenes ; Palladium ; Asymmetric catalysis ; P and N ligands ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Palladium complexes L2PdX2 containing various group Va ligands and weakly coordinating anions are active catalysts for the carbonylation of olefin substrates. These catalytic systems, though gaining significance in industry for the synthesis of polyketones, are normally characterised by a low chemoselectivity. This derives from the numerous possibilities for initiation and termination reactions which lead to different catalytic cycles and from facile multiple alternating insertion reactions of olefins and carbon monoxide. Based on experiments carried out under conditions of low selectivity and on previously published data, the factors involved in the control of the regio-, chemo- and stereoselectivity for those reactions are discussed, taking current ideas and model studies involving the above palladium complexes into consideration.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301103
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  • 99
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    Dichlorogermylene-Alkyldichlorophosphane Reactions Revisited: Characterisation of Bis(trichlorogermyl)phosphanes, Trichlorogermyldiphosphanes, and Ge-P Heterocycles (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1611-1618 
    Details
    ISSN: 0009-2940
    Keywords: Alkyldichlorophosphanes ; Insertions ; Carbene homologues ; Germanium ; Phosphonium germanate(II) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of alkyldichlorophosphanes 1 (RPCl2; R = tert-butyl: 1a, R = isopropyl; 1b, R = 1-adamantyl: 1c) with the germanium dichloride dioxane complex were followed by 31P NMR. Depending on the organic substituents and the reaction conditions, mixtures of trichlorogermylphosphanes RP(GeCl3)2 4a-c, RPHGeCl3 5a-c, diphosphanes R(H)PP(H)GeCl3 6a-c, R(Cl)PP(H)GeCl3 7a, b cyclophosphanes, and Ge-P heterocycles such as triphosphadigermolanes (RP)3(GeCl2)2 8a, b and tetraphosphagermolane (RP)4)GeCl2 10b are formed. As a further unexpected byproduct of the reaction of 1a with GeCl2-dioxane, a small amount of tri-tert-butyl(trichlorogermyl)cyclotetraphosphane 9a was isolated. From the reaction of 1c with two equivalents of GeCl2-dioxane, separation from byproducts 5c and 6c by crystallisation furnished colourless crystals of 4c (R = 1-adamantyl) as the first pure organylbis(trichlorogermyl)phosphane. Surprisingly, the reaction of isoprophylphosphane with germanium tetrachloride, intended to prepare 5a, led to crystalline isopropylphosphonium trichlorogermanate(II) 11. The structures of molecular 4c and 9a and ionic 11 were determined by X-ray crystallography.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301109
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  • 100
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    Synthesis and Structure of Trimethyllead Niobocene DihydrideDedicated to Professor Jörg Lorberth on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1629-1631 
    Details
    ISSN: 0009-2940
    Keywords: Lead ; Niobium ; Hydrides ; Group 5 ; Group 14 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of niobocene trihydride [Cp2NbH3] with ClPbMe3 in the presence of amine affords the plumbido dihydride complex [Cp2NbH2(PbMe3)] (1). Compound 1 represents the first example of a stable complex with neighbouring hydride and terminal plumbyl substituents. The structure of this compound has been established by NMR and IR spectroscopy and confirmed by an X-ray structure analysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301112
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