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  • Digitale Medien  (2.541)
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  • 1990-1994  (2.541)
  • 1950-1954
  • 1905-1909
  • 1991  (2.541)
  • Inorganic Chemistry  (773)
  • Biochemistry and Biotechnology  (742)
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  • Genetics  (192)
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  • Digitale Medien  (2.541)
  • Zeitschrift/Serie
  • Loseblatt
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  • 1990-1994  (2.541)
  • 1950-1954
  • 1905-1909
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  • 1
    Digitale Medien
    Digitale Medien
    Variation between strains of the flour beetle Tribolium castaneum in relative performance on five flours (1991)
    Springer
    Entomologia experimentalis et applicata 60 (1991), S. 173-182 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Genetics ; evolution ; host adaptation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract When populations are exposed to different environments, evolutionary processes can lead either to genetically differentiated strains or to the appearance of increased generalism at the individual level. For evolution to occur, genetic variability in performance in different environments is required. Here, intraspecific genetic variation across environments was estimated in the flour beetle Tribolium castaneum (Herbst) by comparing the responses of two strains of T. castaneum to different flour types. Replicated groups from each strain were allowed to develop on either the standard whole wheat medium or on one of four novel flours (wheat, rice, corn and oat). In several of the novel flours, clear differences in mean development time or population size of one or both strains were seen relative to performance in the standard medium. Moreover, the strains differed significantly in their phenotypic responses to the flours. One strain did particularly poorly on oat flour. Reduced oviposition, reduced larval survivorship and increased larval cannibalism were examined as possible causes of the low productivity on oat flour. These three factors accounted for about 70% of the reduction in population size when this strain oviposited and developed in oat flour. The difference between these two outbred strains in response to these five flours suggests that genetic variation in resource use is present within T. castaneum and may also be present within strains and natural populations in grain storage facilities. Such variation would permit an evolutionary response to selection in multiple environments (flours). This process has agricultural implications when several types of grain are stored in a single location because it could eventually lead to the evolution of highly generalized populations of T. castaneum, an important pest of stored products.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00177038
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  • 2
    Digitale Medien
    Digitale Medien
    Molecular analysis of iron transport in plant growth-promotingPseudomonas putida WCS358 (1991)
    Springer
    BioMetals 4 (1991), S. 36-40 
    Details
    ISSN: 1572-8773
    Schlagwort(e): Iron transport ; Siderophores ; Pseudomonas putida ; Genetics ; Receptors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary Root-colonizingPseudomonas putida WCS358 enhances growth of potato in part by producing under iron-limiting conditions a yellow-green, fluorescent siderophore designated pseudobactin 358. This siderophore efficiently complexes iron(III) in the rhizosphere, making it less available to certain endemic microorganisms, including phytopathogens, thus inhibiting their growth. At least 15 genes distributed over five gene clusters are required for the biosynthesis of pseudobactin 358. High-affinity iron(III) transport in strain WCS358 is initiated by an 86-kDa outer membrane receptor protein (PupA) which appears to be specific for ferric pseudobactin 358. PupA shares strong similarity with TonB-dependent receptor proteins ofEscherichia coli, which suggests a TonB-like protein in strain WCS358 is required for iron(III) transport. Strain WCS358 possesses a second uptake system for ferric pseudobactin 358 and structurally diverse ferric siderophores produced by other microorganisms. A second receptor gene (pupB) responsible for iron transport from pseudobactin BN7 or pseudobactin BN8 has been identified. The production of this and certain other ferric siderophore receptor proteins requires that strain WCS358 be grown in the presence of these siderophores. An apparent regulatory gene required for the expression ofpupB is located adjacent topupB. Two positive regulatory genes have been identified which can independently activate, under low-iron(III) conditions, transcription of genes coding for the biosynthesis of pseudobactin 358.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01135555
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  • 3
    Digitale Medien
    Digitale Medien
    Immunoglobulin allotypes are not associated with HLA-antigens, autoantibodies and clinical symptoms in systemic lupus erythematosus (1991)
    Springer
    Rheumatology international 11 (1991), S. 179-182 
    Details
    ISSN: 1437-160X
    Schlagwort(e): Immunoglobulin allotypes ; Systemic lupus erythematosus ; Genetics ; Gm ; Km ; HLA-antigens ; Autoantibodies ; Clinical symptoms
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Immunoglobulin heavy chain (G1m, G2m, G3m, A2m) and kappa light chain (Km) allotype and phenotype frequencies of 323 central European Caucasian patients with systemic lupus erythematosus (SLE) were examined and correlated with various genetic, serologic and clinical markers of SLE. No significant associations were found between immunoglobulin allotypes or phenotypes and all 20 parameters tested (nephritis, vasculitis, arthralgias, photosensitivity, discoid lesions, central nervous system disease, Raynaud's phenomenon, sex, anti-Ro, anti-La, anti-nRNP, HLA-DR1-DR7, HLA phenotypes B8-DR3, B7-DR2). It could therefore be assumed that Gm, A2m and Km allotypes were not associated with HLA-antigens and had no influence on the serologic and clinical expression of SLE.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00332558
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  • 4
    Digitale Medien
    Digitale Medien
    Hemochromatosis and pyruvate kinase deficiency (1991)
    Springer
    Annals of hematology 62 (1991), S. 188-189 
    Details
    ISSN: 1432-0584
    Schlagwort(e): Hemochromatosis ; Pyruvate kinase deficiency ; Hereditary anemia ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Hemochromatosis has been reported in several patients with chronic hemolytic anemia due to pyruvate kinase deficiency. We describe here a further patient with such an association and review the literature on the subject. We hypothesize that iron overload may occur in patients with pyruvate kinase deficiency who are also carriers of the hereditary hemochromatosis gene.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01703147
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  • 5
    Digitale Medien
    Digitale Medien
    Association between a restriction fragment length polymorphism at the liver/islet cell (GluT 2) glucose transporter and familial Type 2 (non-insulin-dependent) diabetes mellitus (1991)
    Springer
    Diabetologia 34 (1991), S. 734-736 
    Details
    ISSN: 1432-0428
    Schlagwort(e): Genetics ; diabetes mellitus ; restriction fragment length polymorphism ; glucose-transport ; familial
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Patients with Type 2 (non-insulin-dependent) diabetes mellitus and a strong family history of the disease may represent a sub-group where genetic factors play a pree-minent role in transmission of the disease. A defect in the liver/islet cell glucose transporter (GluT 2) could explain many of the pathophysiological features of the disease. In order to test the hypothesis that genetic variation at the GluT 2 locus contributes genetic susceptibility to Type 2 diabetes, 60 unrelated Caucasian diabetic patients with at least one affected sibling were genotyped for a Taq 1 restriction fragment length polymorphism marker. Hybridisation with a cDNA GluT 2 probe identified two alleles of sizes 13 kilobase (T1) and 19 kilobase (T2). The allele frequencies in the diabetic group with a family history were significantly different from those in a racially-matched control population of 122 subjects with no personal or family history of the disease (diabetic patients T1=0.96, T2=0.04, control subjects T1=0.89, T2=0.11, p〈 0.03). However, when the study was repeated with 54 diabetic patients with indeterminate family history, statistical significance was not reached although the allele frequencies showed a similar trend. The findings of this study support the hypothesis that a genetic variant of the liver/islet cell glucose transporter may contribute to familial susceptibility in Type 2 diabetes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00401519
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  • 6
    Digitale Medien
    Digitale Medien
    Shared genetic susceptibility of Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetes mellitus: contributions of HLA and haptoglobin (1991)
    Springer
    Diabetologia 34 (1991), S. 350-355 
    Details
    ISSN: 1432-0428
    Schlagwort(e): Genetics ; Type 1 (insulin-dependent) diabetes mellitus ; Type 2 (non-insulin-dependent) diabetes mellitus ; HLA ; haptoglobin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Epidemiologic data suggest that having a parent with Type 2 (non-insulin-dependent) diabetes mellitus increases the risk for Type 1 (insulin-dependent) diabetes in siblings of a Type 1 diabetes proband. This increase in risk is consistent with a shared genetic susceptibility between Type 1 diabetes and Type 2 diabetes. We contrast genetic risk factors in three sets of families, consisting of (1) a single Type 1 diabetic child (proband) and non-diabetic parents, (2) multiple Type 1 diabetic siblings and non-diabetic parents, and (3) at least one Type 1 diabetic child and at least one Type 2 diabetic parent. Previous studies have demonstrated that HLA region genes, which elevate the risk in Type 1 diabetes, have no significant effect with respect to the risk for developing Type 2 diabetes. An earlier report cited a contribution by the haptoglobin locus to genetic susceptibility for Type 2 diabetes. We provide evidence that a high risk HLA antigen (HLA-DR3) is decreased to a greater extent in Type 1 patients with a Type 2 parent than in Type 1 patients in which the parents are not diabetic. The role of HLA-DR4 is maintained in these families, with an unexpectedly significant increased rate of transmission of the HLA-DR4 allele from Type 2 parent to Type 1 offspring. The role of haptoglobin in these families does not appear to be important, either with respect to association with diabetes or with respect to linkage with a secondary susceptibility locus. These results indicate that families with a Type 2 parent and Type 1 child, heavily determined by HLA-DR4 linked factors, may represent a homogeneous subset of diabetes susceptibility.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00405008
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  • 7
    Digitale Medien
    Digitale Medien
    The effect of size at birth, maturation threshold and genetic differences on the life-history of Daphnia magna (1991)
    Springer
    Oecologia 86 (1991), S. 243-250 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Daphnia ; Life-history ; Genetics ; Variation ; Maturation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Life-history traits of 101 clones from two populations of Daphnia magna were measured under controlled environmental conditions in the laboratory. Some individuals had four juvenile instars, others had five. This depended on their length at birth and on the population they came from. Females in the group with five juvenile instars were smaller at birth but larger and older at maturity than those with four juvenile instars. Within groups of females with equal numbers of preadult instars (instar groups) age and size at maturity increased with size at birth. This relationship differed significantly among instar groups for both age and size at maturity. Significant differences in age and size at maturity between two populations became non-significant when size at birth was used as a covariable in AN-COVA. Within populations, size at birth depended on the clone and on the parity of the clutch. First-clutch offspring were considerably smaller than those from later clutches. The results suggest that variability in life-history traits is common within and between clones, but that most of this variation can be accounted for by size at birth and the number of pre-adult instars.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00317537
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  • 8
    Digitale Medien
    Digitale Medien
    Genetic differences in the effects of competitive and non-competitive NMDA receptor antagonists on locomotor activity in mice (1991)
    Springer
    Psychopharmacology 104 (1991), S. 17-21 
    Details
    ISSN: 1432-2072
    Schlagwort(e): MK-801 ; Phencyclidine ; Ketamine ; CGP 39551 ; CGS 19755 ; NPC 12626 ; Locomotor activity ; Genetics ; NMDA/glutamate receptor complex ; Mice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effects of non-competitive (MK-801, phencyclidine, and ketamine) and competitive (CGP 39551, CGS 19755, and NPC 12626) N-methyl-d-aspartate (NMDA) receptor antagonists on locomotor activity in inbred CBA and C57, and in outbred NMRI mice were examined. Administration of the non-competitive NMDA antagonists produced a dose-dependent increase in well-coordinated locomotor activity at lower doses, followed by a bizarre behavioral syndrome (head weaving, body rolling, rotations, ataxia) after higher doses. The pharmacological profile of the competitive antagonists CGP 39551, CGS 19755, and NPC 12626 was more complex. CGP 39551 dose-dependently inhibited locomotor activity, whereas CGS 19755 and NPC 12626 displayed a biphasic action, that is low doses inhibited locomotor activity, whereas higher doses produced mild behavioral stimulation. The behavioral effects of NMDA antagonists appear to be genetically determined, since CBA animals were most sensitive to both noncompetitive and competitive antagonists, followed by NMRI and C57 animals. The differential effects of NMDA antagonists in various strains of mice suggest that the observed behavioral differences may be due to genetic differences in the NMDA/glutamate receptor channel complex.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02244548
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  • 9
    Digitale Medien
    Digitale Medien
    Genes encoding ribulosebisphosphate carboxylase and phosphoribulokinase are duplicated in Pseudomonas carboxydovorans and conserved in carboxydotrophic bacteria (1991)
    Springer
    Archives of microbiology 157 (1991), S. 92-96 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Carboxydotrophic bacteria ; Ribulosebis-phosphate carboxylase ; Phosphoribulokinase ; Hybridization ; Plasmids ; Genetics ; CO2 fixation ; Alcaligenes eutrophus ; Pseudomonas carboxydovorans ; Rhodospirillum rubrum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Heterologous gene probes derived from cfxLp and cfxPp genes of Alcaligenes eutrophus H16 revealed the presence of structural genes encoding ribulosebisphosphate carboxylase (Rubisco) and phosphoribulokinase (PRK) on the genome of carboxydotrophic bacteria. The two genes were found to be rather conserved. In Pseudomonas carboxydovorans OM5 cfx genes reside on the plasmid pHCG3 and the chromosome as well, indicating that they are duplicated. Also in all plasmidharboring carboxydotrophic bacteria cfxL and cfxP structural genes were found to be plasmid-coded. Our results extend the list of carboxydotrophy structural genes residing on the plasmid pHCG3 and strongly support the idea that the components essential for the chemolithoautotrophic utilization of CO by Pseudomonas carboxydovorans OM5 are plasmid-coded. A cfxL gene probe from Rhodospirillum rubrum did not detectably hybridize with DNA from any of the carboxydotrophic bacteria examined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00245342
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  • 10
    Digitale Medien
    Digitale Medien
    Evidence that genetic differences in habituation and GABAergic mechanisms may be related to sensitivity to ethanol and development of ethanol tolerance in mice (1991)
    Springer
    Psychopharmacology 105 (1991), S. 13-21 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Habituation ; GABA ; Ethanol sensitivity ; Ethanol tolerance ; Genetics ; Mice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Habituation to a test environment following daily exposure for 5 days was examined in three genetically different strains of mice. C57 animals showed significant habituation to the new environment already on the second day. The habituation of NMRI mice was significant on the third day, whereas CBA mice showed no habituation at all during the experimental period. There was no difference between the animal strains in learning capacity in a passive avoidance test, but CBA mice displayed a significant increase in latency in their performance. When tested for sensitivity to the convulsant actions of GABAergic antagonists, picrotoxin produced seizures at lower doses in CBA as compared to NMRI and C57 mice, whereas there was no difference between the strains in the seizure activity produced by the specific GABA receptor antagonist bicuculline. When the animals were tested for sensitivity to ethanol in a horizontal wire test, ethanol (2 g/kg, IP) produced muscle relaxation in CBA mice whereas the performance of NMRI and C57 was not affected. A large dose of ethanol (4 g/kg, IP) produced a significantly longer sleeping time in CBA mice as compared to NMRI and C57 animals. Ethanol-produced hypothermia was, however, similar in all animals. Environment-dependent development of tolerance to ethanol following daily injections of ethanol for 4 days was examined. C57 mice showed the most rapid development of tolerance towards ethanol's hypnotic actions, whereas CBA mice showed no tolerance to this effect of ethanol. No difference between the strains to the development of tolerance to ethanol's hypothermic effects was observed. The present findings indicate that sensitivity to ethanol and ethanol tolerance are complex phenomena which cannot be adequately characterized by measuring only one single functional response to ethanol. The possibility that a genetically determined perturbation in the functions of the GABA receptor-coupled chloride channel, noted as variable sensitivity to picrotoxin, may be of importance for the observed disturbance in habituation to a new environment, for the different sensitivity to ethanol, and for the different rate of development of ethanol tolerance is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02316858
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  • 11
    Digitale Medien
    Digitale Medien
    Clinical polydiagnostic studies in a large Swedish pedigree with schizophrenia (1991)
    Springer
    European archives of psychiatry and clinical neuroscience 240 (1991), S. 188-190 
    Details
    ISSN: 1433-8491
    Schlagwort(e): Families ; Genetics ; Polydiagnostic approach ; Schizophrenia ; Swedish family complex
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A polydiagnostic computerized diagnostic system for psychosis was used in a Swedish family complex, and 51 patients with psychiatric symptomatology were examined with eight main diagnostic systems for schizophrenia and three systems for schizophrenic subgroups. All patients fulfilled the criteria for schizophrenia according to Taylor et al., 50 according to Carpenter, 41 according to RDC, and 31 of the 51 according to DSM-III and DSM-III-R. The hypothesis that the patients in the Swedish family complex differ from other phenotypes of schizophrenia must be refuted based on the data of the present study.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02190762
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  • 12
    Digitale Medien
    Digitale Medien
    Genetic architecture of growth curve parameters in chickens (1991)
    Springer
    Theoretical and applied genetics 83 (1991), S. 24-32 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Genetics ; Growth curve ; Body weight ; Chickens
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Genetic improvement in growth of poultry has traditionally proceeded via selection for body weight at a fixed age. Due to increased maintenance costs and reproductive problems of adult broiler breeders, the potential for genetic manipulation of the growth curve has been receiving increased interest. Research of both male and female progeny of a three-way diallel cross was used to investigate the inheritance of growth curve parameters. The Laird form of the Gompertz equation was used to determine growth curve parameters, and was suited to the juvenile growth data frequently collected from meat-type chickens. Growth rate exhibited significant heterosis due to both autosomes and the sex chromosomes. Age at inflection point also exhibited significant average heterosis, though only among females. Growth rate was also influenced by average line effects, as was age at inflection point. Maternal effects had no influence on growth curve parameters, while additive sex linkage was observed for growth rate. Phenotypic and genetic correlations were calculated among the growth curve parameters and suggest that specific breeding programs could alter the growth trajectory of the contemporary broiler chicken. Moderate heritabilities were observed for the growth curve parameters and support the hypothesis that the growth curve could be altered via genetic manipulation of early postnatal growth, especially during the first 14 days post-hatch.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00229222
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  • 13
    Digitale Medien
    Digitale Medien
    Genetic analysis of rye (Secale cereale L.) Genetics of male sterility of the G-type (1991)
    Springer
    Theoretical and applied genetics 82 (1991), S. 761-764 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Rye ; Male sterility ; Genetics ; Gene location ; Trisomies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The genetics and relationships between the genes in rye located in the nucleus and cytoplasm of the male sterility of the G-type were investigated. A factor inducing male sterility was found in the cytoplasms or rye cv Schlägler alt and rye cv Norddeutscher Champagner. Monogenic inheritance was observed in linkage tests. Using primary trisomies of rye cv Esto, the nuclear gene ms1 was found to be located on chromosome 4R. Modifying genes, probably masked in normal cytoplasm but expressed in male-sterility-inducing cytoplasm together with gene ms1, were located on chromosomes 3R (ms2) and 6R (ms3). Mono-, di-, and trigenic inheritance types were found in backcross progenies of trisomies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00227322
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  • 14
    Digitale Medien
    Digitale Medien
    Molecular heterogeneity and genetics of Vicia faba seed storage proteins (1991)
    Springer
    Theoretical and applied genetics 81 (1991), S. 50-58 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Vicia faba ; Legumin ; Vicilin ; Structure ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Legumin and vicilin were purified from seeds of Vicia faba L. var. Scuro, characterized in different electrophoretic systems, and used to produce polyclonal antibodies in rabbits. Two-dimensional electrophoretic studies showed a wide range of heterogeneity in the subunits of both legumin and vicilin. Legumin was found to be composed of 29 disulphide-linked subunit pairs with different molecular weight and/or isoelectric point. Western blot analysis of legumin of several mutants revealed molecular polymorphism based on a corresponding gene family. Three different α-major legumin patterns were found, and inheritance studies showed that the 34.3-kD legumin polypeptide is the product of one locus, Lg-1α, which is the first legumin genetic locus described in Vicia faba. Vicilin was found to be composed of as many as 59 subunits distributed in a molecular weight range of 65.7 to 42.8 kD (major polypeptides) and 37.2 to 15.2 kD (minor polypeptides), with different isoelectric points. A model is proposed that explains the possible formation of the minor subunits and the major subunits of 48.2 and 46 kD molecular weight (MW) from proteolytic cleavages and/or glycosilation of precursor polypeptides. Ten different vicilin electrophoretic patterns were observed among the analyzed accessions, which showed large molecular polymorphism that proved to be under genetic control.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00226111
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  • 15
    Digitale Medien
    Digitale Medien
    α-Amylase structural genes in rye (1991)
    Springer
    Theoretical and applied genetics 82 (1991), S. 771-776 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Secale cereale ; RFLP ; α-Amylase ; Genetics ; Isozymes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Rye α-Amy1, α-Amy2, and α-Amy3 genes were studied in the cross between inbred lines using wheat α-amylase cDNA probes. The α-Amy1 and α-Amy2 probes uncovered considerable restriction fragment length polymorphism, whereas the α-Amy3 region was much more conserved. The numbers of restriction fragments found and the F2 segregation data suggest that there are three α-Amy1 genes, two or three α-Amy2 genes, and three α-Amy3 genes in rye. These conclusions were supported by a simultaneous study of α-amylase isozyme polymorphism. The F2 data showed the three individual α-Amy1 genes to span a distance of 3cM at the locus on chromosome 6RL. The genes were mapped relative to other RFLP markers on 6RL. On chromosome 7RL two α-Amy2 genes were shown to be separated by 5 cM. Linkage data within α-Amy3 on 5RL were not obtained since RFLP could be detected at only one of the genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00227324
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  • 16
    Digitale Medien
    Digitale Medien
    Creutzfeldt-Jakob disease among libyan jews (1991)
    Springer
    European journal of epidemiology 7 (1991), S. 490-493 
    Details
    ISSN: 1573-7284
    Schlagwort(e): Creutzfeldt-Jakob diseases ; Prion disease ; Jews ; Libya ; Genetics ; Pathophysiology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The focus of CJD among Jews of Libyan origin has been recognized for two decades, but the reasons underlying it were unknown. Prevailing views suggested transmission from sheep infected with scrapie. However, recent data show that in fact CJD in this ethnic group is a genetically determined disease due to a point mutation on the codon 200 of the prion protein gene. The clinical characteristics of CJD in this group, and particularly the less common periodic activity in the EEG, are reviewed. New findings include peripheral neuropathy of the demyelinating type in two cases, presumably due to involvement of Schwann cells. The pathophysiology of the disease includes, presumably, a focal post-translational modification of the prion protein, (predisposed by the mutation). Later, the disease progresses through cell-to-cell transmission.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00143127
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  • 17
    Digitale Medien
    Digitale Medien
    Mutants of Nicotiana plumbaginifolia with specific resistance to auxin (1991)
    Springer
    Molecular genetics and genomics 228 (1991), S. 361-371 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Plant ; Hormone ; Genetics ; Hypocotyl ; Development
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have isolated nine independent auxin-resistant mutants of Nicotiana plumbaginifolia by culturing M2 seedlings in the presence of indole-3-acetic acid ethyl ester or 1-naphthaleneacetic acid at concentrations which significantly inhibit hypocotyl elongation of the wild type. The mutations were induced by treating seed with ethyl methanesulphonate and were found in the course of screening 10 000 individual M2 families. Auxin resistance was in all cases the result of a mutation at a single, nuclear locus. The dominance relationships of two of the mutants could be defined as recessive or dominant; all other mutants showed partial dominance. In contrast to previously described mutants of Arabidopsis and N. plumbaginifolia, all of the present mutants were specifically resistant to auxin; the mutants were cross-resistant to several auxins, but showed no increased resistance to cytokinin, abscisic acid, ethylene or 1-amino-cyclopropane-1-carboxylic acid. The importance of the choice of the selection criterion for the isolation of specific resistance traits is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00260628
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  • 18
    Digitale Medien
    Digitale Medien
    Genotype differences in catecholamine concentrations in hypothalamus, intramedial hyperstriatum ventrale, and optic tectum of newly hatched chicks (1991)
    Springer
    Neurochemical research 16 (1991), S. 105-112 
    Details
    ISSN: 1573-6903
    Schlagwort(e): Genetics ; catecholamine ; brain ; imprinting ; development
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract This study was designed to compare catecholamine concentrations among three brain areas of four pureline populations of visually isolated chicks. The purelines used were a commercial male line, a fertility selected line, an unselected fertility control line, and unselected White Jersey Giants. In general, male chicks had significantly larger brain weights than females. Six catecholamine-related compounds (norepinephrine, epinephrine,l-DOPA, dopamine, DOPAC, and MHPG) were measured via HPLC-ECD. No significant differences in neurochemical concentration were observed for any line or brain area due to sex of the chick. The hypothalamus (HT) contained the greatest concentration of catecholamines in all lines, followed by the intramedial hyperstriatum ventrale (IMHV) and optic tectum (OT). The HT exhibited consistent lateralization in all lines with the right HT containing ca. 30% more catecholamines than the left HT. While no consistent lateralization was observed among the other brain areas, the IMHV exhibited significantly different degrees of lateralization among the populations. Neuronal activity, as measured by MHPG:NE and DOPAC:DA ratio varied by line within each brain area. There were line differences for MHPG:NE in the HT, IMHV, and OT, while line differences for DOPAC:DA were observed in the HT. Since differences among purelines have been demonstrated in this study, care must be given to precisely define the genotype of chicks used in behavioral and neurochemical research.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00965696
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  • 19
    Digitale Medien
    Digitale Medien
    Inheritance of stalk rot resistance in cauliflower (Brassica oleracea var. Botrytis L.) (1991)
    Springer
    Euphytica 57 (1991), S. 93-96 
    Details
    ISSN: 1573-5060
    Schlagwort(e): Brassica oleracea ; Cauliflower ; Stalk rot ; Screening ; Genetics ; Resistance ; Sclerotinia sclerotiorum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The inheritance of resistance in cauliflower to stalk rot (Sclerotinia sclerotiorum (Lib.) de Bary) was investigated in population from six generations of six crosses. Disease incidence was recorded on 4 parents, 6 Fs 1, 6 Fs 2 and 12 back-crosses in a screenhouse under artificially created epiphytotic conditions. Resistance to stalk rot in this set of parents was found to be polygenic and under the control of recessive genes and due primarily to additive gene action. A breeding strategy emphasizing recurrent selection should lead to improvement in resistance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00023065
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  • 20
    Digitale Medien
    Digitale Medien
    Point group symmetry and cartesian force constant redundancy (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 19-29 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A procedure for identifying redundancy in the Cartesian force constant matrix is described, and a prescription is given for generating the entire matrix of second derivatives from the minimal set of information. A proof is supplied which demonstrates that the number of nonredundant rows corresponding to a symmetry unique atom is necessarily less than three if the atom is invariant with respect to a symmetry operation of the point group other than the identity or inversion. Furthermore, only one row is required if the atom lies on a threefold or higher-order rotation axis. An application of the procedure to the evaluation of harmonic force constants by numerical differentiation of gradient vectors is briefly described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390105
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  • 21
    Digitale Medien
    Digitale Medien
    An intermediate neglect of differential overlap model for second-row transition metal species (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 31-45 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An intermediate neglect of differential overlap (INDO) model for elements of the second transition series is described. Values of exponents for the radial portion of the Slater basis atomic orbitals, the orbital ionization energies, and the beta (or bonding) parameters for these elements are reported. Use of the model to investigate equilibrium geometries, relative energy ordering of geometric isomers, spectroscopic transition energies, energy ordering of state wave functions of different symmetry, trends in dipole moments, and equilibrium stretching frequencies is reported. The results indicate that the INDO method is capable of yielding quality results for species containing atoms of the second transition series.
    Zusätzliches Material: 11 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390106
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  • 22
    Digitale Medien
    Digitale Medien
    Improved quadrature methods for three-center nuclear attraction integrals with exponential-type basis functions (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 625-645 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The numerical properties of a two-dimensional integral representation [J. Grotendorst and E.O. Steinborn, Phys. Rev. A 38, 3857 (1988)] of the three-center nuclear attraction integral with a special class of exponential-type orbitals (ETO'S), the B functions [E. Filter and E.O. Steinborn, Phys. Rev. A 18, 1 (1978)] are examined. B functions span the space of ETO'S. The commonly occurring ETO'S can be expressed in terms of simple finite sums of B functions. Hence, molecular integrals for other ETO'S, like the more common Slater-type orbitals, may be found as finite linear combinations of integrals with B functions. The main advantage of B functions is the simplicity of their Fourier transform that makes the derivation of relatively simple general formulas for molecular integrals with the Fourier transform method possible. The integrand of the integral representation mentioned above shows sharp peaks causing, in the case of highly asymmetric charge distributions, slow convergence of the quadrature method used by Grotendorst and Steinborn. New quadrature schemes are presented that use quadrature rules based on Möbius transformations. These rules are well suited for the numerical quadrature of functions that possess a sharp peak at or near a single boundary of integration [H.H.H. Homeier and E.O. Steinborn, J. Comput. Phys., 87, 61 (1990)]. Numerical results are presented that illustrate the fact that convergence of the new quadrature schemes is about a factor two faster in case of highly asymmetric charge distributions.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390409
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  • 23
    Digitale Medien
    Digitale Medien
    Single-excitations-adapted molecular orbitals for a simplified description of electronic excited states (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 681-688 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An orbital transformation that minimizes the sum of the squares of the off-diagonal Hamiltonian elements between the singly excited configurations is described. The resulting single-excitations-adapted molecular orbitals (SEAMOS) are found to be very suitable for the description of electronic excited states. The test calculations on the singlet and triplet excited states of the N2, CO, and H2CO molecules are presented.
    Zusätzliches Material: 12 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390505
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  • 24
    Digitale Medien
    Digitale Medien
    Energy deposition mechanisms and biochemical aspects of DNA strand breaks by ionizing radiation (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 709-727 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A theoretical model based on physical, chemical, and biochemical mechanisms has been presented to evaluate the yields of DNA strand breaks (single and double) as a function of linear energy transfer (LET) or -dE/dx. Energetic heavy charged particles are considered explicitly to provide a general theory for low- as well as for high-LET radiation. There are three main features of the calculation: (a) track structure considerations for the energy deposition pattern, (b) three-dimensional structure of DNA molecules to provide information on the exact location of damage, and (c) a Monte-Carlo scheme to simulate the diffusion processes of water radicals. To avoid the complexities of a cellular medium, an aqueous solution of DNA is considered in the calculation. When the results of the calculations are compared with experimental measurements of the yields of strand breaks in mammalian DNA (exposed in a cellular complex), reasonable agreement is obtained. However, only those experimental data have been compared where there were no enzyme repair processes. The method of calculation has also been extended to study breaks in higher-order structures of DNA molecules such as chromatin. Specific limitations of the present model have been pointed out for making further improvements.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390508
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  • 25
    Digitale Medien
    Digitale Medien
    Electronic aspects of LADH catalytic mechanismPaper presented at 29th Sanibel Symposia, 1989. (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 767-786 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electronic aspects of the catalytic mechanism of liver alcohol dehydrogenase (LADH) are studied with the help of ab initio analytical gradient SCF MO methods. Three points are considered: (i) role of the catalytic zinc; (ii) geometry and electronic structure of the transition state for the hydride transfer reactions; and (iii) factors affecting the energy gap for the hydride transfer step, namely, substrate binding to zinc, reaction field, and serine 48 effects on the potential energy profile. The coordination sphere of the catalytic zinc has been modeled with an ammonia molecule and two SH- groups; complexes with CH3O-, CH3OH, and CH2O have been studied; a (6, 2, 2, 2, 1/6, 2, 1/3, 2) basis set has been used for Zn++; a (5, 2, 1, 1/3, 2) was used for oxygen, carbon, and sulfur; and a (3, 1) was used for hydrogen atoms. The hydride step was studied with two model systems: pyridinium cation/1,4-dihydropyridine coupled to the CH3O-/CH2O reaction, and cyclopropenyl cation/cyclopropene coupled to the CH3O-/CH2O system. For the latter, the role of Ser48 has been studied at the supermolecule level. The calculation on the hydride transfer step has been done at a 4-31G basis set level. The results obtained shed new light on the sources of catalytic activity of liver alcohol dehydrogenases.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390603
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  • 26
    Digitale Medien
    Digitale Medien
    Theoretical treatment of chemisorption using an Ab initio SCF Green-matrix formalism (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 839-849 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We present a treatment of chemisorption that uses the Green matrix of the surface and the admolecule, as well as a cluster calculation of a small surface cluster. Since full HF-SCF-band structures with nonlocal exchange are available now for larger systems for a couple of years, it is possible to treat the substrate surface and the admolecule on equal footing. This offers a natural way to solve the embedding problem. We have applied the formalism to the adsorption of H2 on beryllium and show that in contrast to cluster calculations there appears a binding, which is experimentally verified.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390608
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  • 27
    Digitale Medien
    Digitale Medien
    A study on the electronic spectra of vinylpyridines and 1,2-(dipyridyl)ethylenes. Molecular orbital calculations (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 211-226 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electronic absorption spectra of 2-, 3-, and 4-vinylpyridines and 1,2-(2,3-dipyridyl), 1,2-(2,4-dipyridyl), 1,2-(3,4-dipyridyl), and 1,2-(4,4-dipyridyl) ethylenes have been investigated in polar and nonpolar solvents. A correlation has been made between the geometry of the molecule and the observed spectrum. Molecular orbital calculations have been carried out using the INDO/S—CI procedure and a limited geometry optimization. The solvent effect at the MO level has been calculated. MO calculations predicted the existence of nπ* transitions that were not observed experimentally. The wave functions of the different CI states were calculated. The experimental transition energy as well as oscillator strength corresponded satisfactorily with the calculated ones. The observed transitions were assigned according to the results of MO calculations.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390210
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  • 28
    Digitale Medien
    Digitale Medien
    Masthead (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991) 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390301
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  • 29
    Digitale Medien
    Digitale Medien
    The discovery of the chemical evolution of singlet oxygen. Some current chemical, photochemical, and biological applications (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 251-267 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: From the speculations of G. N. Lewis in 1916, [J. Am. Chem. Soc. 38, 762 (1916)], the spectral predictions of R.S. Mulliken [Nature 122, 505 (1928)], and the quantum mechanical treatment by E. Hückel [Z. Phys. 60, 423 (1930)], the three lowest states of molecular oxygen (3Σg-, 1Δg, and 1Σg+) remained spectroscopic elusives until Gerhard and Lisa Herzberg [G. Herzberg, Nature 133, 759 (1934); L. Herzberg and G. Herzberg, Astrophys. J. 105, 353 (1947); G. Herzberg and L. Herzberg, Astrophys. J. 108, 167 (1948)], precisely defined them by observed infared transitions. The excited singlets remained of interest mainly to atmospheric spectroscopists and astrophysicists, and research on these species was scarce. The discovery in 1963 by A.U. Khan and M. Kasha [J. Chem. Phys. 39, 2105 (1963)] of the simple chemical production of singlet molecular oxygens by the aqueous reaction of hydrogen peroxide and hypochlorite released an explosion of research on the neglected species. Fifteen research symposia and research treatises confirm the broad range of chemical activities of singlet oxygen. The extension to biological systems is now proceeding, with surprising evidence of involvement of natural processes, including the action of singlet oxygen in white blood cell phagocytosis.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390305
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  • 30
    Digitale Medien
    Digitale Medien
    Polarization propagator calculation of spectroscopic properties of molecules (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 371-386 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We propose 10 desirable features or criteria for general purpose methods to be applied to the calculation of a range of spectroscopic properties. We discuss the second-order polarization propagator approximation (SOPPA) in light of these criteria by giving the actual computational expression used as well as a few numerical examples taken from the theory of NMR spectra (magnetic shieldings and spin-spin coupling constants). We demonstrate that SOPPA comes close to fulfilling these criteria.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390314
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  • 31
    Digitale Medien
    Digitale Medien
    High-resolution infrared analysis of the ν17 band of pyridine (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 423-436 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method for analyzing asymmetric top rovibrational bands displaying both blended and resolved features is described. The two-phase computational procedure uses a modified version of the asymmetric rotor-band contour program FASTPLOT to generate a preliminary set of upperstate spectroscopic constants. The parameters are subsequently refined by employing the assigned line-fitting formalism of the ASYROT program using both resolved and blended features. The technique is detailed in a comprehensive analysis of the ν17 band of pyridine. Inclusion of quartic centrifugal distortion constants was found to satisfactorily model a high-resolution (0.004 cm-1) spectrum of this band, yielding a standard deviation of 0.00137 cm-1. The variation in the rotational parameters with vibrational quantum number is examined in terms of possible weak rovibrational perturbations to the ν17 state. An ab initio calculation of the ν17/ν27 Coriolis coupling constant indicates the observed results are consistent with the interaction of these two vibrational states.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390318
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  • 32
    Digitale Medien
    Digitale Medien
    Announcement (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 521-521 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390324
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  • 33
    Digitale Medien
    Digitale Medien
    The system of harmonically interacting particles: An exact solution of the quantum-mechanical problem (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 173-181 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An original procedure has been developed to determine the eigenvalues and the eigenfunctions of quantum-mechanical many-body systems with a harmonic oscillator interaction. Exact solutions in the explicit form have been obtained for the case of systems containing three groups of identical particles. For the system containing two groups of identical particles, a solution in the adiabatic approximation has been obtained and compared with the exact one.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390207
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  • 34
    Digitale Medien
    Digitale Medien
    Fourth international conference on mathematical and computational chemistry (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 229-229 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390212
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  • 35
    Digitale Medien
    Digitale Medien
    Professor Michael Kasha (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 233-233 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390303
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  • 36
    Digitale Medien
    Digitale Medien
    Quantum chemical calculations on buckminsterfullerene and related structures. II. The electronic structure and spectra of some Cn and CnCa2+ cages (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 331-344 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390311
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  • 37
    Digitale Medien
    Digitale Medien
    International journal of quantum chemistry - A journal devoted to quantum theory and computations in chemistry, condensed matter physics, and biology. Editorial - program and policies (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 1-2 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390102
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  • 38
    Digitale Medien
    Digitale Medien
    Excited and ionized states of RuO4 and OsO4 studied by SAC and SAC-CI theories (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 93-113 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The excitation and ionization spectra of RuO4 and OsO4 are studied theoretically by the symmetry-adapted cluster (SAC) and SAC-CI theories. This is the attempt to assign whole of the spectra by ab initio calculations including electron correlations. In the ground state, electron correlations work to reduce the polarity of the M-O bond overestimated in the Hartree-Fock calculation. The Os-O bond is stronger than is the Ru-O bond, which is reflected in the differences of the excitation and ionization spectra of RuO4 and OsO4. The excitation energies of the experimental spectra are well reproduced by the SAC-CI theory, though the calculated intensities of some peaks are very small in comparison with the experiments. The outer-valence ionization spectra calculated by the SAC-CI theory agree well with the experimental photoelectron spectra. Some shake-up peaks that are accompanied with an electron-transfers from oxygen to metal are also calculated.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390110
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  • 39
    Digitale Medien
    Digitale Medien
    A comment on classical rainbow angles for atom-atom scattering (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 159-162 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The dependence of the rainbow angle on the depth of the potential well, the equilibrium distance, andthe force constant of the potential are discussed for several potential functions.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390205
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  • 40
    Digitale Medien
    Digitale Medien
    A general treatment of vibration-rotation coordinates for triatomic molecules (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 183-196 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An exact, within the Born-Oppenheimer approximation, body-fixed Hamiltonian for the nuclear motions of a triatomic system is presented. This Hamiltonian is expressed in terms of two arbitrarily defined internal distances and the angle between them. The body-fixed axis system is related to these coordinates in a general fashion. Problems with singularities and the domain of the Hamiltonian are discussed using specific examples of axis embedding. A number of commonly used coordinate systems including Jacobi, bond-length-bond-angle, and Radau coordinates are special cases of this Hamiltonian. Sample calculations on the H2S molecule are presented using all these and other coordinate systems. The possibility of using this Hamiltonian for reactive scattering calculations is also discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390208
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  • 41
    Digitale Medien
    Digitale Medien
    International journal of quantum chemistry - a journal devoted to quantum theory and computations in chemistry, condensed matter physics, and biology. Editorial - Program and Policies (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 1-2 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560400102
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  • 42
    Digitale Medien
    Digitale Medien
    Quantum rigid dipole in a permanent electric field. I. Rigorous treatment (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 33-53 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A behavior of a quantum rigid and pointlike dipole in a permanent electric field is under study. A dependence of a number of librational energy levels on the strength of the electric field is investigated on the basis of some rigorous results for the appropriate normal Jacobian matrices.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560400106
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  • 43
    Digitale Medien
    Digitale Medien
    A BSSE-free SCF algorithm for intermolecular interactionsSupported in part by the Hungarian Research Fund (OTKA No. 785). (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 139-148 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A very simple modification of the usual (∼N4) SCF procedure is proposed, permitting the exclusion of basis set superposition errors (BSSE) in problems of intermolecular interactions. No a posteriori corrections are required. The results of this “CHA/F method” are numerically close to those of the Boys-Bernardi correction scheme but are free from the “overcompensation” characteristic of the latter at smaller distances.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560400112
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  • 44
    Digitale Medien
    Digitale Medien
    Symmetry adapted formulation of the generalized Brillouin theorem (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 243-264 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The singly excited functions satisfying Brillouin theorem are expressed as linear combinations of configuration-state functions for any spin and spatial symmetries (atomic or molecular) and for any reference wave function. The generality of the formulation is ensured by the use of the irreducible tensor method that can be adapted to any symmetry point group of interest. The expansion coefficients are simply written as products of fractional parentage coefficients, spin- and orbit-recoupling coefficients, and phase factors. The formalism is illustrated for some atomic (Kh) and molecular (C∞v, C3v, and Td) configurations. Group theoretical techniques are also used to correlate the Brillouin conditions within a chain of groups.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560400207
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  • 45
    Digitale Medien
    Digitale Medien
    Quantum-Chemical modeling of catecholamine storage including continuum solvent effects (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 299-304 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A model for catecholamine storage in vesicles is analyzed within the SCRF-CNDO/2 approach including continuum solvent effects. The model considers the approach of cationic norepinephrine (NE) to a positively charged guanidinium moiety. Ion-pair formation is found for the whole range of dielectric constants. Even though stable states of H-bonded partners are found for large dielectric constants, this process is ruled out to occur because it involves too high energies. It appears that the medium's polarity is determinant in lowering the energy barrier between the ion-pair complex and the separated partners. Thus, as the medium dielectric constant increases, the equilibrium between the two states is enhanced.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560400303
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  • 46
    Digitale Medien
    Digitale Medien
    Announcement (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 519-519 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390323
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  • 47
    Digitale Medien
    Digitale Medien
    Dirac-Fock self-consistent field method for closed-shell molecules with kinetic balance and finite nuclear size (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 487-517 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We present a general method of implementing the kinetic balance condition within the Dirac-Fock (DF) self-consistent field (SCF) formalism for closed-shell molecular structure. We review the steps leading to the derivation of DF SCF equations for closed-shell molecules, particularly as formulated by Matsuoka et al. In the present approach, the large component of the molecular spinors are expanded in terms of atomic basis spinors of spherical-type Gaussian functions, with the small component related to the large component by the kinetic balance condition. It is shown that imposing the kinetic balance condition on geometric Gaussian-type basis functions allows us to obtain the Fock matrix elements, involving both the large and the small components, form the standard nonrelativistic Cartesian-type matrix elements. By using properties of orthogonal polynomials, the solid spherical harmonics are expressed in Cartesian form, thus providing a general basis for transformation of one- and two-electron-matrix elements, obtained from a Cartesian Gaussian-type basis, to a spherical Gaussian-type basis. The advantages of using kinetically balanced geometric Gaussian-type basis functions in molecular DF calculations including finite-size nucleus effects are emphasized. For the sake of completeness, we have added in an appendix corrections to the nuclear attraction matrix elements for the finite-size nucleus already derived by Matsuoka.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390322
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  • 48
    Digitale Medien
    Digitale Medien
    Ab initio MRD-CI calculations for breaking a chemical bond in a molecule in a crystal or other solid environment. III. Me2N—NO2 decomposition of dimethylnitramine in a large crystalline environment (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 541-560 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Recently we extended our strategy for MRD-CI (multireference double excitation-configuration interaction) calculations, based on localized/local orbitals and an “effective” CI Hamiltonian, for molecular decompositions of large molecules to breaking a chemical bond in a molecule in a crystalline or other solid environment.Our technique begins with an explicit quantum chemical SCF calculation for a reference molecule surrounded by a number of other molecules in the multipole environment of more distant neighbors. The resulting canonical molecular orbitals are then localized, and the localized occupied and virtual orbitals in the region of interest are included explicitly in the MRD-CI with the remainder of the occupied localized orbitals being folded into an “effective” CI Hamiltonian. The MRD-CI calculations are then carried out for breaking a bond in the reference molecule. This method is completely general in that the space treated explicitly, as well as the surrounding space, may contain voids, defects, deformations, dislocations, impurities, dopants, edges and surfaces, boundaries, etc.Dimethylnitramine is the smallest prototype of the energetic R2N - NO2 nitramines, such as the 6-member ring RDX or the 8-member ring HMX. Decomposition of energetic compounds is initiated in the solid by a breaking of the target bond. Thus, it is crucial to know the difference in energy between breaking a bond in an isolated energetic molecule versus in the molecule in a solid. In the present study, we have carried out MRD-CI calculations for the Me2N - NO2 dissociation of dimethylnitramine in a dimethylnitramine crystal. The cases we investigated were one dimethylnitramine molecule (surrounded by 53 and 685 neighboring dimethylnitramine molecules represented by multipoles), three dimethylnitramine molecules, and three dimethylnitramine molecules (surrounded by 683 neighbors). All multipoles were cumulative atomic multipoles up through quadrupoles. The MRD-CI calculations on dimethylnitramine required large numbers of reference configurations from which were allowed all single and double excitations.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390403
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  • 49
    Digitale Medien
    Digitale Medien
    Second-order polarization propagator calculations of dynamic dipole polarizabilities and C6 coefficients (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 667-679 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The frequency-dependent dipole polarizability, α(E), is calculated using the second-order polarization propagator approximation (SOPPA). We have shown how to express α(E) as a function of E2 and thus obtained a form of α(E) that can be used to compute C6-coefficients without invoking complex arithmetic. For He we find that SOPPA recovers a large fraction of the correlation contribution for all frequencies, whereas for H2 where the correlation contributions are much smaller and also basis set-dependent, we find a less definite trend of SOPPA relative to RPA.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390504
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  • 50
    Digitale Medien
    Digitale Medien
    Transition properties from multiple scattering X-Alpha Calculations: A study of NO2 (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 71-91 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The usefulness of the MS-Xα method for calculating molecular transition properties is investigated in a study of NO2. Two-dimensional potential surfaces are obtained in C2v symmetry for the X̃2A1/Ã2B2 system. Potential curves that approximately follow the asymmetric stretch coordinate are also presented: On investigation, no symmetry-broken solutions were found. At all nuclear geometries investigated, the muffin-tin sphere radii were chosen by an energy-minimization technique. The inclusion of corrections to the muffin-tin form of the Xα total energy is shown to be essential, if the computed surfaces are to be qualitatively correct. The transition dipole moment connecting the two states is evaluated as a function of nuclear coordinates, using the transition-state approximation. Finally, the radiative decay of a single vibronic level in NO2 is modeled and the relevance to experiment is discussed.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390109
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  • 51
    Digitale Medien
    Digitale Medien
    Monohydration selectivity mechanism of alkali cations in the potassium channel of excitable biomembranes (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 131-147 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Nonempirical quantum chemical method Hartree-Fock-Roothan LCAO SCF MO in a two-exponent Dunning basis with the use of an extended set of Gaussian functions by Huzinaga-Dunning with consideration of electron correlation according to the Meller-Plesset theory of excitations of the second order was used to study monohydrates of Li+, Na+, K+, and HCOO- ions. The indicated basis was supplemented with polarization functions of d-type on the O atom and of p-type on the hydrogen atom as well as with diffusion functions of p-type on the oxygen atom. It has been found that binding energies of the water molecule with Li+, Na+ appeared to be higher and with K+ lower than with HCOO- · H2O. Potential curve shapes of K+ + H2O and HCOO- + H2O reactions are shown to be similar. The molecular mechanism of K+ channel selectivity of an excitable membrane is explained on the basis of the obtained calculations.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390203
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  • 52
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    Digitale Medien
    Collision-induced emission of O2(b1Σg+ → a1Δg) in the gas phaseNRCC No. 31208. (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 287-298 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In flow tube studies of the quenching of O2(b1Σg+), broad band emission of O2(b):M collision complexes was found to appear under the discrete rotational lines of the 0-0 band of the b1Σg+ → a1Δg electric quadrupole transition at higher oxygen pressures and on addition of foreign gases. Bimolecular rate constants for the collision-induced emission processes have been derived from the ratio of the intensities of the discrete lines and the continuum as well as from low-resolution measurements of the relative intensities of the b → a and b → X bands as a function of O2 and added gas pressure. They range from ≈10-21 cm3 s-1 for He to ≈4 × 10-19 cm3 s-1 for PCl3 vapor.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390307
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  • 53
    Digitale Medien
    Digitale Medien
    A realistic model for curve crossing in diatomic molecules (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 523-539 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We present a model system for the study of curve-crossing situations in diatomic molecules. All model parameters are determined by the potential energy topology. No coupling functions are fitted. The standard approximation schemes (Born-Oppenheimer approximation, adiabatic approximation, and the generator coordinate approximation) are then applied. The result of these numerical experiments suggest that the generator coordinate approximation is able to remove 80%-90% of the nonadiabatic effect on all levels throughout the crossing region.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390402
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  • 54
    Digitale Medien
    Digitale Medien
    A partial recurrence relation for reduced class coefficients of the symmetric group (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 593-604 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An expression for the product of a single-cycle class [(1)N - P(p)]N and an arbitrary class [(1)l1(2)l … (N)lN]N of the symmetric group has recently been conjectured. This expression involves a sum over a relatively small number of reduced class sums, depending on p indices. A further conjecture is formulated and demonstrated, according to which reduced class coefficients (RCCS) involving cycles whose length is expressed by means of a single index can be related to corresponding coefficients in the product of [(1)N - P+1(p - 1)]N with an arbitrary class sum. Consequently, the problem of evaluating the general class sum product reduces to that of obtaining a relatively small set of fundamental RCCS containing no single-index cycles. The conjectures mentioned can be used to evaluate the product [(1)N - p(p)]N · [(1)N - q(q)]N in terms of fundamental RCCS that can all be obtained from the product [(r)]r · [(r)]r, where r = min(p, q). For the latter product, we use a result due to Boccara.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390406
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  • 55
    Digitale Medien
    Digitale Medien
    Masthead (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991) 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390501
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  • 56
    Digitale Medien
    Digitale Medien
    Structure reports for 1988. Edited by G. Ferguson and J. Trotter, metals and inorganic compounds, Vol. 55A, Kluwer, Dordrecht, 1989 (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 39 (1991), S. 647-647 
    Details
    ISSN: 0020-7608
    Schlagwort(e): Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/qua.560390410
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  • 57
    Digitale Medien
    Digitale Medien
    Photochemische Reaktionen von Übergangsmetall-Organyl-Komplexen mit Olefinen, 3. [4 + 5]-Cycloaddition konjugierter Diene an Tricarbonyl(η5-2,4-dimethyl-2,4-pentadienyl)mangan (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 3-12 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Manganese-mediated cyclization ; Nine-membered carbocycles ; Manganese complexes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Photochemical Reactions of Transition Metal Organyl Complexes with Olefines, 31). - [4 + 5] Cycloaddition of Conjugated Dienes to Tricarbonyl(η5-2,4-dimethyl-2,4-pentadienyl)manganeseTricarbonyl(η5-2,4-dimethyl-2,4-pentadienyl)manganese [1] reacts photochemically with the acyclic conjugated dienes 1,3-butadiene [A], 2-methyl-1,3-butadiene [B], (E)-1,3-pentadiene (C), (E,E)-2,4-hexadiene (D), 2,4-dimethyl-1,3-pentadiene (E), 2,4-hexadien-1-ol (F), and methyl 2,4-hexadienoate (G) in a formal [4 + 5] cycloaddition to give tricarbonylmanganese complexes with η3:2-2,6-cyclononadien-1-yl ligands (2A-2G). In addition, the reaction of 1 with A yields thermolabile [η3:2:2-1-(3-butene-1,2-diyl)-1,3-dimethyl-2,6-cyclononadiene]dicarbonylmanganese (3A) and E,E and E,Z isomers of [η3-1-(2-butene-1,1-diyl)-1,3-dimethyl-2,6-cyclononadiene]tetracarbonylmanganese (4A, 4A] as byproducts. Similarly, 1 reacts with B to form tetracarbonyl[η3-1-(3-methyl-2-butene-1,1-diyl)-1,3,6-trimethyl1-2,6-cyclononadiene]manganese (4B) in a side reaction. The crystal and molecular structures of tricarbonyl(η3:2-1,3,5,5,7-pentamethyl-2,6-cyclononadien-1-yl]manganese (2E) and of 3A are determined by X-ray structure analyses. In each of the formally octahedral complexes unusual long manganese-carbon bonds are found for one coordinated CC double bond of the hydrocarbon ligands.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240102
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  • 58
    Digitale Medien
    Digitale Medien
    Derivate des Borols, XVI Bis(borol)nickel-Komplexe2) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 17-23 
    Details
    ISSN: 0009-2940
    Schlagwort(e): (Borole)nickel complexes ; Nucleophilic substitution at boron ; 1H-Borole ; Dihydro-1H-borolediide ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Derivatives of Borole, XVI1), - Bis(borole)nickel Complexes2)The dilithium 1-(dialkylamino)dihydroborolediides Li2[C4H4-BNR2] 2a, b: R = Me, Et) react with NiCl2 · DME to give bis(borole)nickel complexes Ni(C4H4BNR2)2. Nucleophilic substitution reactions are used to produce a large variety of derivatives Ni(C4H4BR)2 1 (e.g. R = H, tBu, F, Cl, Br, I, OH, OMe). Treatment of Ni(C4H4BCl)2 (tg) with LiO(CH2)3OLi in THF produces a polymer and a dinuclear complex (μ-{η5:η5-[(CH2)3(OBC4H4)2]}2Ni2 (3) which crystallizes from CH2Cl2 as solvate 3 · CH2Cl2. The complexes 1g and 3 · CH2Cl2 are characterized by X-ray diffraction work. Barriers to internal ring-ring rotation are measured by variable-temperature NMR spectroscopy. The B - H bond of Ni(C4H4BH)2 (1a) is remarkably inert and does not react with H2O or with carboxylic acids in THF at room temperature. With PhCHO slow formation of the benzyloxy compound Ni(C4H4BOCH2Ph)2 (1 m) is observed at 100°C. For typical complexes such as the phenyl derivative 1e cyclic voltammetry in CH2Cl2 reveals an irreversible oxidation at 1.32 and a quasi-reversible reduction at -1.37 V vs. SCE.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240104
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  • 59
    Digitale Medien
    Digitale Medien
    Derivate des Borols, XVII {η5-[1-(Diisopropylamino)borol]}metall-Komplexe: Synthesen, Protonierung, interne Rotation (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 25-29 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Borole complexes ; {η5-[1-(Diisopropylamino)borole]}metal complexes, internal rotation of, protonation of ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Derivatives of Borole, XVII1). - {η5-[1-(Diisopropylamino)borole]}metal Complexes: Syntheses, Protonation, Internal RotationNew complexes M(CO)4L (M = Cr, W), cis-M(CO)2L2 [M = Mo, W (not isolated)], and (COD)NiL have been prepared from the Diels-Alder dimer L2, where L is 1-(diisopropylamino)borole, C4H4BNiPr2. Complexes of L can be protonated at the nitrogen atom to give stable salts such as [Cr(CO)4(LH)]BF4, [Fe(CO)3(LH)]BF4, [(C6Me6)Ru(LH)]BF4, and [CpCo(LH)]BF4; B  -  N bond dissociation is not observed. Barriers to internal rotation have been determined by variable temperature NMR spectroscopy for Cr(CO)4L, (COD)NiL, and NiL2. Three processes have been identified: rotation of the NiPr2 group around the B  -  N bond, gear-mesh rotation of the isopropyl groups around the C  -  N bonds, and rotation of L with respect to the counter ligands.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240105
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  • 60
    Digitale Medien
    Digitale Medien
    Darstellung von (Perfluoralkyl)halogeno-1,3-diselenetanen aus entsprechenden Selenocarbonylfluoriden und Umsetzungen mit Bortrichlorid sowie Arsenpentafluorid1) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 51-61 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Selenocarbonyl compounds, perfluorinated ; 1,3-Diselenetanes, perhalogenated ; 2-Selenabicyclo[2.2.1]hept-5-enes ; 1,3-Diselenetan-2-ylium hexafluoroarsenates ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Preparation of (Perfluoroalkyl)halogeno-1,3-diselenetanes from the Corresponding Selenocarbonyl Fluorides and Reactions with Boron Trichloride or Arsenic Pentafluoride1)Reactions of Hg(SeRt)2 (Rt = C2F5, C3F7, CF3) with (C2H5)2 All or All3 in octamethylcyclotetrasiloxane produce the unstable perfluoroalkaneselenocarbonyl fluorides 1 [R1 = CF3 (1 a), C2F5 (1 b), CF3Se (1 c)]. These compounds are very reactive and polymerize to rubberlike products. On heating the polymers decompose almost quantitatively to the monomers or dimers. In CFCl3 solution 1 dimerizes at 20°C in sunlight to the corresponding cis/trans-1,3-diselenetanes 2. The structure of 2 b is determined by single crystal X-ray diffraction. Different selenocarbonyl derivatives add to unsymmetrically substituted 1,3-diselenetanes 3. 1 a and 1 b react with cyclopentadiene to form the [4 + 2] cycloaddition products 4a and 4c. Halogen exchange reactions take place between 2a  -  d and BCl3. The cis-isomers react much faster than the trans-isomers to give a mixture of cis-, trans-forms of 5. When 2c,d is treated with BCl3 it is possible to isolate and characterize the pure trans-isomer 2d, which is separated by preparative gas chromatography from 5c,d. Fluorine abstraction with formation of 1,3-diselenetan-2-ylium ions (6a  -  f) are accomplished by reactions of 2 or 3 with AsF5 in SO2.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240109
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  • 61
    Digitale Medien
    Digitale Medien
    Molecular Structure of Hg[C(COF)=SF2=O]2 (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 87-88 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Alkylidenesulfur difluoride oxide ; Carbon-sulfur double bond ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Hg[C(COF) = SF2 = O]2 is prepared by the reaction of FCO — CH = SF2 = O with HgF2. This compound represents the third known example of an alkylidenesulfur difluoride oxide. Its molecular structure is the same as that of the most abundant of the three isomers of FCO-CH = SF2 = O. This is assumed to be the result of weak intramolecular Hg… O contacts. With the exception of the fluorine atoms bound to sulfur, all atoms lie approximately in one plane.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240114
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  • 62
    Digitale Medien
    Digitale Medien
    Asterane, XXII. Synthese eines doppelten Tetraasterans: Nonacyclo[10.8.0.02,11.04,9.04,19.06,17.07,16.09,14.014,19]eicosan (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 103-109 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Asteranes ; Cage compounds ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Asteranes, XXII1).  -  Synthesis of a Double Tetraasterane: Nonacyclo[10.8.0.02,11.04,9.04,19.06,17.07,16.09,14.014,19]eicosane1,4,5,8-Tetrahydronaphthalene-2,3-dicarboxylic anhydride (9) is dimerized by UV light in dioxane yielding four isomeric [2 + 2] adducts whose methyl ester derivatives are elucidated spectroscopically. The structures of the major products 14 and 16 have been confirmed by X-ray structure analysis. Degradation of the carboxylic groups of 14 afforded the title compound 5.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240118
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  • 63
    Digitale Medien
    Digitale Medien
    Darstellung aromatischer Fluor-Verbindungen durch nucleophilen Austausch von Nitro-Gruppen gegen Fluorid (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 157-162 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Fluoro compounds, aromatic ; Nitrite exchange by fluoride ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis of Aromatic Fluoro Compounds by Nucleophilic Exchange of Nitro Groups by FluorideThe synthesis of aromatic fluoro compounds from the respective nitro compounds by nucleophilic substitution of nitrite by fluoride is described. Reasonable yields in case of nonactivated nitro compounds are only obtained if the nitrite formed in the reaction is eliminated by acylation. 1-Fluoro-3-nitrobenzene (2) was obtained from 1,3-dinitrobenzene (1), and 1-fluoro-3,5-dinitrobenzene (9) as well as 1,3-difluoro-5-nitrobenzene (10) from 1,3,5-trinitrobenzene (8) in yields up to 92% by reaction of nitro compounds with potassium fluoride in sulfolane at 180 - 200°C in the presence of phthaloyl dichloride (6); 1,2-difluoro-4-nitrobenzene (12) was formed in 58% yield from 2,4-dinitro-1-fluorobenzene (11) in the presence of pyromellitoyl tetrachloride (13).
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240124
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  • 64
    Digitale Medien
    Digitale Medien
    Synthese und Struktur von Bis[bis(diisopropylamino)phosphino]chalkogeniden (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 13-16 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Diphosphines, tetrakis(diisopropylamino) ; Phosphinous anhydrides ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis and Structure of Bis[bis(diisopropylamino)phosphino]chalcogenidesPhosphorodiamidous chalcogeno-anhydrides [(R2N)2P]2X (R = Me2CH; X = S, Se, Te) (2a-c) have been obtained by insertion of elemental sulfur, selenium, or tellurium into the P-P bond of the corresponding diphosphane (1). The structure of 2a and 2c has been confirmed by an X-ray diffraction.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240103
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  • 65
    Digitale Medien
    Digitale Medien
    (Perfluoralkyl)(dimethylamino)sulfonium-hexafluoroarsenate (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 31-38 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Fluorosulfonium salts, reaction with nucleophiles ; (Perfluoroakyl)(dimethylamino)sulfonium salts, preparation and structures of ; Methoxysulfinyl hexafluoroarsenate, alkylation with ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: (Perfluoroalkyl)(dimethylamino)sulfonium HexafluoroarsenatesMeN = S(CF3)2 (5) is alkylated by Me3O⊕ AsF⊖6 to Me2N-S(CF3)⊕2 AsF⊖6 (4). From 5 and MeOSO⊕ AsF⊖6 (6) MeOS(O)-N(Me)S(CF3)⊕2 AsF⊖6 (7) is formed as a relatively stable primary product. Decomposition of 7 gives the expected 4 only in poor yield. Nucleophilic substitution of the sulfur-bonded fluorine in CF3SF⊕2 AsF⊖6 (8) by Me3SiNMe2 yields CF3S(NMe2)⊕2 AsF⊖6 (9). Similarly, (CF3)2CFSF⊕2 AsF⊖6 (10) reacts with dimethyl(trimethylsilyl)amine to give (CF3)2CFS(NMe2)⊕2 AsF⊖6 (11). The structures of 4 and 9 are elucidated by X-ray analyses, and the influence of the substituents on the bonding is discussed.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240106
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  • 66
    Digitale Medien
    Digitale Medien
    Übergangsmetall-Silyl-Komplexe, 36 Zur Frage von Gold-Gold-Wechselwirkungen bei Ph2P[CH2]1(2) PPh2 verbrückten zweikernigen Gold-Silyl-Komplexen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 63-67 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Dinuclear gold complex ; Silyl complex ; Gold-gold interaction ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Transition-Metal Silyl Complexes, 361).  -  On the Question of Gold-Gold Interactions in Ph2P[CH2]t(2)PPh2-Bridged Dinuclear Gold Silyl ComplexesDinuclear silyl gold complexes of the type dppm(AuSiR3)2 (1) or dppe(AuSiR3)2 (2) are prepared by the reaction of dppm-(AuCl)2 or dppe(AuCl)2 with two equivalents of LiSi(aryl)3 or LiSi(SiMe3)3 The complex dppe[AuSi(SiMe3)3]2 (2 c) exhibits crystallographic inversion symmetry, and therefore the distance between both gold atoms is a maximum. In dppm-(AuSiPh3)2 (1b) a gold-gold interaction between both gold atoms is observed [Au  -  Au 316.80(3) pm].
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240110
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  • 67
    Digitale Medien
    Digitale Medien
    Cyclobuten-Ringöffnung: Eine nützliche Reaktion zur Synthese doppelsträngiger Moleküle (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 149-156 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Cyclobutene, ring-opening ; Poly Diels-Alder reaction ; Molecules, double-stranded ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Cyclobutene Ring Opening: A Useful Reaction for the Synthesis of Double-Stranded MoleculesSyntheses and ring-opening reactions of the compounds endo-5a - e and 9a - c, all containing cyclobutene rings, are described. From these experiments it is concluded that compound 9a is a useful AB-type Diels-Alder monomer for the synthesis of well-defined double-stranded molecules. The stereochemistry of the adducts endo-4b and endo-5d is determined by X-ray structure analysis.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240123
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  • 68
    Digitale Medien
    Digitale Medien
    Zur Reaktion von Dialkylphosphiten mit α-Enonen, I Synthese und Allyl-Umlagerung von (1-Hydroxy-2-alkenyl)- und (1-Hydroxy-2-cycloalkenyl)phosphonsäure-dimethylestern (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 175-184 
    Details
    ISSN: 0009-2940
    Schlagwort(e): α-Enones, regioselective 1,2-addition of dimethyl phosphite to ; Allylic rearrangement of dialkyl (1-hydroxy-2-alkenyl)phosphonates ; 1-Alkenylphosphonates, 3-acetyloxy- ; 1-Alkenylphosphonates, 3-hydroxy- ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reaction of Dialkyl Phosphites with α-Enones, I. - Synthesis and Allylic Rearrangement of Dimethyl (1-Hydroxy-2-alkenyl)- and (1-Hydroxy-2-cycloalkenyl)phosphonatesVarious β,γ-unsaturated α-hydroxyphosphonates 3 are prepared in good yields by NaOCH3-catalyzed regioselective 1,2-addition of dimethyl phosphite to acyclic and cyclic α-enones at -35°C. On acid-catalyzed acetylation, the allylic α-hydroxyphosphonates 3 (R1, R2 + H) rearrange under thermodynamic control; yielding the new 3-acetyloxy-1-(cyclo)alkenyl derivatives 8, from which the transposed allylic alcohols 11 are readily obtained. Using shorter reaction times, acetylation of compounds 3 affords mixtures of 1- and 3-acetylated products, 10 and 8, respectively.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240126
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  • 69
    Digitale Medien
    Digitale Medien
    Trioxypentafulvenes, 2 synthesis of 1-substituted 2,3,6-trioxypentafulvenes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 207-212 
    Details
    ISSN: 0009-2940
    Schlagwort(e): 2,3,6-Trioxypentafulvenes ; Keto-enol tautomerism ; Push-pull system ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Syntheses of 2,3,6-trioxypentafulvenes with a free position at the ring are described, in which the protection of the C-3 hydroxy group as methoxy or acetoxy derivative has been required. The difference in the behavior of the title compounds in relation to the previously reported 1,4-disubstituted 2,3,6-trihydroxypentafulvenes 2a-e, which only exhibit enol forms, is discussed and attributed to the disappearance of the push-pull system formed by the C-3 enol group and the C-4 electron-withdrawing substituent.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240131
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  • 70
    Digitale Medien
    Digitale Medien
    Neue O6-Makrocyclen mit 2,2-Bis(2-furyl)propan-Einheiten (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 233-235 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Hexaoxacyclotriacontadodecaenes ; Macrocycles ; 2,2-Bis(2-furyl)propane ; 2,5-Bis[1-(2-furyl)-1-methylethyl]furan ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New O6 Macrocycles with 2,2-Bis(2-furyl)propane UnitsThe macrocycles 3a and 6 are prepared in 29 and 16% yield by cyclization of dilithiated 2,2-bis(2-furyl)propane (1) and 2,5-bis[1-(2-furyl) 1-methylethyl]furan (5), respectively, with ethyl N,N-dimethylcarbamate (2).
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240135
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  • 71
    Digitale Medien
    Digitale Medien
    Umlagerungen von 1,4,4- und 2,2,5-Trimethylbicyclo[3.2.1]oct-6-yl-Kationen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 237-240 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Bicyclo[3.2.1]oct-6-yl cations ; Wagner-Meerwein rearrangements ; Alkyl-bridged ions ; Conformational effects ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Rearrangements of 1,4,4- and 2,2,5-Trimethylbicyclo[3.2.1]oct-6-yl Cations1,4,4-Trimethylbicyclo[3.2.1]oct-6-yl cations (18) are generated from the tosylhydrazone 7, by nitrous acid deamination of the amines 6 and 8, and by acetolysis of the brosylates 21 and 24. The product distributions are but slightly affected by the configuration (exo vs. endo) of the leaving groups. The predominant product, 1,4,4-trimethylbicyclo[3.2.1]octan-exo-6-ol (11) is formed without significant redistribution of a 6-2H label. The degenerate Wagner-Meerwein rearrangement of the parent bicyclo[3.2.1]oct-6-yl cation is virtually eliminated by the presence of two methyl groups at C-4. Enhanced conformational strain, raising the barrier to ring flipping, accounts for these observations. Minor products (12, 13) arise from a 7,6-hydride shift of 18, followed by Wagner-Meerwein rearrangement. When the 2,2,5-trimethylbicyclo[3.2.1]oct-6-yl cation (19) is generated directly from the tosylhydrazone 17, the tertiary alcohol 13 is obtained as the major product. The conformational barrier to Wagner-Meerwein rearrangement is compensated by the incipient stabilization of the tertiary carbocation 20.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240136
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  • 72
    Digitale Medien
    Digitale Medien
    Notizen/Notes Synthesis of 1-Phenyl-1,2- and 4-Phenyl-1,5-dihydropentalenes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 403-405 
    Details
    ISSN: 0009-2940
    Schlagwort(e): 1,2-Dihydropentalenes ; 1,5-Dihydropentalenes ; Rearrangements ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An efficient one-pot synthesis of 3-substituted 1-phenyl-1,2-dihydropentalenes from α,β-unsaturated ketones is described. These compounds can be rearranged to their 1,5-dihydro isomers using different methods such as acid catalysis and vacuum-flash thermolysis or by chromatography on alumina.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240226
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  • 73
    Digitale Medien
    Digitale Medien
    Electrochemical Investigations on Methylenephosphines and Related Systems (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 417-421 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Methylenephosphines ; Voltammetry, cyclic ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electrochemical investigations on a selection of methylenephosphines 1 and related systems are reported. They are shown to possess an irreversible oxidation and reduction wave. An exception is diaminodiphosphene, which reversibly forms a radical anion. A relative ordering of frontier orbitals is possible, based on the redox properties of these systems.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240302
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  • 74
    Digitale Medien
    Digitale Medien
    Die Kristallstrukturen von Kalium-, Rubidium- und Cäsium-trifluororthocarbonat mit einer Bemerkung zum Bariumsulfat-Typ1 (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 321-327 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Trifluororthocarbonates of potassium, rubidium, cesium ; Phase transitions ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The Crystal Structures of Potassium, Rubidium, and Cesium Trifluororthocarbonate and a Remark Concerning the Barium Sulfate Type1)Crystals of potassium, rubidium, and cesium trifluororthocarbonate (9a, 9b, and 9c) have been grown by Ostwald ripening in CH3CN applying a COF2 pressure of 3 bar. According to X-ray single-crystal structure analysis, 9a, 9b, and 9c belong to the baryte-structure family with an pseudotetrahedral anion being dynamically disordered at room temperature. All of the title compounds undergo a phase transition into a monoclinic, completely ordered low-temperature form, which has been refined for 9c. The C - O bond seems to be shortened by polar interactions. The results obtained with 9a, 9b, and 9c at room temperature indicate that the type of disorder found in 9 might be generally present in baryte-type compounds.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240212
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  • 75
    Digitale Medien
    Digitale Medien
    Selektivitäten bei Photoadditionen an multifunktionelle Coffein-Derivate (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 339-345 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Photoadditions ; Caffeine derivatives ; Calculations, AM1 ; Diradicals ; Propellanes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Selectivities in Photoadditions with Multifunctional Caffeine DerivativesElectronically excited stilbene (21*), 4,4′-dichlorostilbene (1*), and 4,4′-dimethoxystilbene (18*) are trapped by caffeine derivatives 2, 13, or 22 with variable results. While 1* and 2 react predominantly at the imino double bond (substitutive and fragmentating additions), 1* or 18* and 13 produce mostly propellanes by [2 + 2] photocycloaddition, which hydrolyze or may be hydrolyzed. 21* and the relatively electron-poor compound 22 produce mostly propellanes, which always show a preponderance of the syn-10, anti-11 stereoisomers. These selectivities as well as the competition with reactions at the imino double bonds are rationalized on the basis of diradical mechanisms with the aid of semiempirical AM1 calculations. Earlier results on closely related transformations are also discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240215
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  • 76
    Digitale Medien
    Digitale Medien
    Addition von Phosphor-Nucleophilen an Benzothiet (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 377-381 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Phosphorus compounds, organic ; Phosphorus heterocycles ; Arbuzov rearrangement ; Mechanism, SN2, SN1 ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Addition Reactions of Phosphorus Nucleophiles to BenzothieteTrialkyl phosphites 4 add to the o-quinoid form 2 of benzothiete (1) to yield the phosphonates 6. An intermolecular migration of an alkyl group from oxygen to sulfur is the most important feature of this transformation. The rearrangement - related to the Arbuzov reaction - can be avoided in a two-step process by the subsequent action of PCl3 and alcohol; thus the phosphonates 10 are generated. Analogous to 2 → 6, dimethyl phenylphosphinate (11) furnishes 13. In contrast, the cyclic esters 14a-d form 2:1 adducts, namely the 12- to 15-membered heterocyclic compounds 17a - d. An intramolecular rearrangement in a 1:1 adduct is only observed for the 1,3,2-dioxaphosphepine 14e, a benzylic system which allows an SN1 process generating the 1,6,2-oxathiaphosphecine 18e. A similar rearrangement at a tertiary carbon center is prevented by the competitive addition of water (1 + 14f → 20).
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240221
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  • 77
    Digitale Medien
    Digitale Medien
    Dispiro-1,2,4-trioxolane durch Ozonolyse von Cycloalkylidencycloalkanen auf Polyethylen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 391-396 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Ozonolysis ; Cycloalkylidenecycloalkanes ; Dispiro-1,2,4-trioxolanes ; Thermolysis ; Photolysis ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Dispiro-1,2,4-trioxolanes by Ozonolysis of Cycloalkylidenecycloalkanes on PolyethyleneOzonolyses of symmetrical (1b - d) and of unsymmetrical cycloalkylidenecycloalkanes (8a, b) afforded the dispiro-1,2,4-trioxolanes 4b - d and 9a, b, respectively. Their thermal decompositions gave mixtures of the cyclic ketones (3) and lactones (6). Photolyses afforded in addition to 3 and 6 the cyclic anhydrides 13, which are isomeric with the corresponding dispiro-1,2,4-trioxolanes.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240224
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  • 78
    Digitale Medien
    Digitale Medien
    Pseudooxokohlenstoff-Anionen der Semidreiecksäure (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 665-669 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Semideltic acid ; Cyclopropenylium cations ; Pseudooxocarbon anions ; Semideltate anions ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Pseudooxocarbon Anions of Semideltic AcidNovel pseudooxocarbon anions of semideltic acid (2) can easily be obtained by stepwise substitution of the dimethylamino groups of the cyclopropenium perchlorate 8. Treatment of 8 with cyanamide or malononitrile in the presence of triethylamine leads to the triafulvenes 9 and 13. Two cyanoimino groups are successfully introduced into the cyclopropenylium system by treating 9 with excess cyanamide/potassium ethoxide. Under the same conditions malononitrile reacts with 13 to yield the potassium salts 14 and 17. The thioamide 26 of semideltic acid is obtained by treating the triphenylphosphonium salt 24 with H2S/pyridine and subsequent hydrolysis of the intermediate 25. With the anions of cyanamide or malononitrile ring-opening reaction of the cyclopropenylium system of 24 occurs to yield the push-pull phosphonium salts 28 and 29.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240334
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  • 79
    Digitale Medien
    Digitale Medien
    Kohlenwasserstoffverbrückte Metallkomplexe, XVIII. Heterometallische Ethylen-verbrückte Komplexe (OC)5ReCH2CH2Mn(CO)5, (OC)5ReCH2CH2Ru(CO)2Cp, (OC)5ReCH2CH2Os(CO)4CH2CH2Re(CO)5 und (OC)5ReCH2CH2CH2Os(CO)4Os(CO)4(CO)4Os(CO)4CH2CH2Re(CO)5 (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1059-1063 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Ethylene-bridged metal complexes ; Ethanediyl complexes ; Manganese, Rhenium, Ruthenium, Osmium carbonyls ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Hydrocarbon-Bridged Metal complexes, XVIII. - Heterometallic Ethylene-Bridged Complexes (OC)5ReCH2CH2Mn(CO)5, (OC)5ReCH2CH2Ru(CO)2Cp, (OC)5ReCH2CH2Os(CO)4CH2CH2Re(CO)5 and (OC)5ReCH2CH2CH2Os(CO)4Os(CO)4(CO)4Os(CO)4CH2CH2Re(CO)5Addition of [(OC)5Re(C2H4)]+ to the carbonylmetallates [Mn(CO)5]-, [RuCp(CO)2]-, [Os(CO)4]2-, [Os3(CO)12]2- affords the title complexes in a directed way. The dynamic behaviour of (OC)5ReCH2CH2Mn(CO)5 in solution is attributed to a dyotropic exchange of the pentacarbonylmetal groups on the CH2CH2 bridge.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240512
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  • 80
    Digitale Medien
    Digitale Medien
    Arsen(III)-, Antimon(III)- und Bismuth(III)-halogenid-Komplexe des [2.2.2]Paracyclophans: Vom lockeren van-der-Waals-Addukt zu stark gerichteten π-Komplexen mit zwei- und dreifacher externer η6-Koordination (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1089-1093 
    Details
    ISSN: 0009-2940
    Schlagwort(e): [2.2.2]Paracyclophane ligand ; (η6)π Complexes ; Arsenic(III) complexes ; Antimony(III) complexes ; Bismuth(III) complexes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Arsenic(III), Antimony(III), and Bismuth(III) Trihalide Complexes of [2.2.2]Paracyclophane: From Weak van der Waals Coordination to Strongly Directional π Complexation with Single or Double External η6 Coordination[2.2.2]Paracyclophane forms the adducts C24H24·AsCl3 (1), C24H24·(SbCl3)2·1/2 C6H6 (2), and C24H24·(BiCl3)3·C6H6 (3). For solutions in polar solvents NMR spectra indicate extensive dissociation and/or fluxionality. In the crystals adduct 1 features a weak addition of the AsCl3 molecule to one open side of a paracyclophane molecule with long intermolecular contacts approaching C3v symmetry. - Crystalline 2 shows SbCl3 coordination to two of the benzene rings of the hydrocarbon in a quasi-centered η6 mode, while one of the benzene rings remains uncoordinated. Chlorine-bridging between antimony atoms leads to tetrameric units (SbCI3)4 in the lattice. - In the bismuth compound 3 each benzene ring of the hydrocarbon is engaged in centroid (η6)π complexation, with the BiCl3 units crosslinked by chlorine bridges. The average of the Bi-ring distances (3.08,2.98, and 2.99 Å) is shorter than for the Sb-ring distances in 2 (3.047 and 3.050 Å), indicating stronger bonding. The crystal benzene is not coordinating.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240516
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  • 81
    Digitale Medien
    Digitale Medien
    Intramolecular, Metallacyclic Organoaluminium, -gallium and -indium Addition Compounds Crystal Structure of 1-Galla-5-azabicyclo[3.3.3]undecane (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1113-1119 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Metallacyclic organoaluminium, -gallium and -indium compounds ; MOVPE precursors ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Intramolecularly base-stabilized four-coordinated metallacyclic organoaluminium, -gallium, and -indium compounds C5H10-Al(CH2)3NMe2 (4), C4H8Ga(CH2)3NMe2 (5), C5H10Ga(CH2)3N-Me2 (6), C5H10GaCH2CH(Me)CH2NMe2 (7), C4H8Ga(CH2)4NMe2 (8), C5H10Ga(CH2)4NMe2 (9), EtAl[(CH2)3]2NMe (10), MeGa-[(CH2)3]2NMe (11), EtGa[(CH2)3]2NMe (12), MeIn[(CH2)3]2NMe (13), and (14) have been synthesized by the reaction of [3-(dimethylamino)propyl]aluminium dichloride (1), [3-(dimethylamino)propyl]gallium dichloride (2), [3-(dimethylamino)-2-methylpropyl]gallium dichloride (3), or [4-(dimethylamino)butyl)gallium dichloride with the respective bis-Grignard reagents or by the reaction of the organometal dichlorides RMCl2 with bis[3-(chloromagnesio)propyl]methylamine or with N,N′-bis[3-(chloromagnesio)propyl]-N,N′-dimethyl ethylenediamine. Aluminium or gallium trichloride reacts with tris[3-(chloromagnesio)propyl]amine to give Al[(CH2)3]3N (15) and Ga[(CH2)3]3N (16). The 1H-, 13C-NMR and mass spectra of the new compounds as well as the X-ray crystal structure of 16 are discussed. 4, 6, and 12 have been tested successfully as MOVPE precursors.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240520
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  • 82
    Digitale Medien
    Digitale Medien
    Übergangsmetallkomplexe von Diazenen, XXVII. Eisencarbonyl-induzierte o-Semidin-Umlagerung von 1-Alkyl-2-aryldiazenen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1143-1148 
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    ISSN: 0009-2940
    Schlagwort(e): Ironcarbonyl complexes ; ortho-Metallation ; o-Semidine rearrangement ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Iron Carbonyl Induced o-Semidine Rearrangement of 1-Alkyl-2-aryldiazenesIrradiation of pentacarbonyl iron in the presence of Me3C - N=N - Ar (Ar=phenyl, p-tolyl, p-CH3OC6H4) produces in the first step ortho-metallated complexes of the type Me3C - N - N(H)RC6H3Fe(CO)3Fe(CO)3 (2a-c, R=H, Me, MeO). In a thermal consecutive step these intermediates undergo an o-semidine rearrangement to Me3C - NFe(CO)3 - Fe(CO)3N(H)RC6H3 (1a-c). The structure of 1a has been elucidated by X-ray structure analysis. Dynamic 13C-NMR spectra indicate restricted rotation of the Me3C group and hindered carbonyl scrambling for the latter and former complexes, respectively.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240525
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  • 83
    Digitale Medien
    Digitale Medien
    Heterogeneous Photocatalysis, IX. Zinc Sulfide Catalyzed Photoreduction of Carbon Dioxide (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1161-1162 
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    ISSN: 0009-2940
    Schlagwort(e): Semiconductor ; Photocatalysis ; Carbon dioxide ; Formate ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Carbon dioxide is catalytically reduced to formate in a suspension of zinc sulfide in water/2,5-dihydrofuran when irradiated (λ ≥ 290 nm). Turnover rates are in the range of 1.5 monolayers CO2/h. No reaction occurs at pH=12, and a very slow one at pH=3.2,5-Dihydrofuran functions as reducing agent which is oxidized to dehydro dimers. When it is substituted by 2-propanol, no CO2 reduction is observed. Semiconductor photocatalysis by a two-electron transfer from zinc sulfide to adsorbed hydrogen carbonate is assumed as the key step of CO2 fixation.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240529
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  • 84
    Digitale Medien
    Digitale Medien
    Cycloadditions, 47. A Route to Functionalized Cyclic Ethers by Intramolecular Cycloadditions of Unsaturated Nitro Ethers (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1181-1186 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Stereoselective cyclizations ; Ethers, cyclic ; Dipolar cycloaddition ; Nitro olefins ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A convenient conversion of aldehydes via nitroolefins 2 into cyclic ethers 6 fused to an isoxazoline ring involves formation of unsaturated nitroalkyl ethers 4 and subsequent intramolecular cycloaddition of an in situ-formed nitrile oxide olefin. The cyclization proceeds with stereoselective formation of trans over cis isomers in the tetrahydrofuran series and opposite stereoselectivity in the tetrahydropyran and hexahydrooxepine series, depending on the substituent R in the original nitro compound, thus providing access to stereoselectively functionalized cyclic ethers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240533
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  • 85
    Digitale Medien
    Digitale Medien
    Intra- und extraannular funktionalisierte [2.2.2]Phane mit Dreifachbindung: Synthese und Eigenschaften (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1223-1227 
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    ISSN: 0009-2940
    Schlagwort(e): Cesium effect ; Clathrate ; Cyclophanes ; Acetylene, diphenyl ; Rigid-group principle ; Tolane ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Intra- and Extraannularly Functionalized [2.2.2]Phanes: Syntheses and PropertiesThe severely strained new cyclophanes 7b-f, consisting of bridged tolane subunits and bearing intraannular substituents R, were prepared mainly to study steric interactions of R with the “π cloud” of the triple bond. These compounds exist in a rigid twisted conformation, whereas the unsubstituted reference compound 7a and the extraannularly functionalized azo compound 9 show C2 symmetry. 9 forms a 1 : 1 clathrate with toluene.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240540
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  • 86
    Digitale Medien
    Digitale Medien
    Chiral Organometallic Reagents, I Stereoselective Exchange of Diastereotopic Bromine Atoms by Lithium in 1,1-Dibromo-3-(trimethylsilyloxy)alkanes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1243-1252 
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    ISSN: 0009-2940
    Schlagwort(e): Carbenoids ; Bromine-lithium exchange ; Asymmetric induction ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Bromine-lithium exchange in 1,1-dibromo-3-(trimethylsilyl-oxy)alkanes 4 and 6 affords the carbenoids 8 and 14, which have been added to ketones, aldehydes, arylboronates, and silylating agents. Diastereoselectivity in the generation and trapping of the carbenoids ranged between 70 - 90% for 8 and 〉90% for 14.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240543
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  • 87
    Digitale Medien
    Digitale Medien
    4,9,14,19-Tetrafunctionalized Pagodanes de novo Synthesis - Functional Group Manipulations (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1271-1289 
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    ISSN: 0009-2940
    Schlagwort(e): Dibenzo compounds, rigid face-to-face ; Photocycloadditions, [6 + 6] Benzo, Benzo ; Pagodanes, 4,9,14,19-tetrafunctionalized ; Functional Group Manipulations ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Various 4,9,14,19-tetrafunctionalized pagodanes are prepared by a de novo route commencing from appropriately substituted isodrin analogues (3, 4). With the 14,19-dimethoxypagodane-4,9-dicarboxylic esters 30/31, isolated after 16 one-pot operations (ca. 40 functional changes) in ca. 6.5% overall yield (ca. 84% per operation, ca. 93% per functional change), the scope for further functional group manipulations on the pagodane sphere is explored (e.g. diketone dicarboxylic ester 35, dimethoxy diketone 37, tetraketone 41). In two face-to-face dibenzo substrates (17, 49), clean photoequilibration with the corresponding syn-o,o'-dibenzo isomers (19, 50) (75: 25 and 80: 20, resp.) is observed upon direct excitation (λ=254 nm).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240547
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  • 88
    Digitale Medien
    Digitale Medien
    Die Synthese von Chlor(trichlormethyl)sulfin, Cl3C(Cl)C=SO (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1311-1312 
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    ISSN: 0009-2940
    Schlagwort(e): Anthracene adducts ; Sulfine, chloro(trichloromethyl)- ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis of Chloro(trichloromethyl)sulfine, Cl3C(Cl)C=SOThe unstable trichlorothioacetyl chloride (2) could be trapped by a Diels-Alder reaction with anthracene to form the adduct 3, which in turn could be oxidized to the corresponding sulfine adduct 4. Finnaly, chloro(trichloromethyl)sulfine (5) was prepared in good yield by vacuum thermolysis (retro Diels-Alder reaction) of 4.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240551
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  • 89
    Digitale Medien
    Digitale Medien
    Organophosphorverbindungen, 48. 1-Halogen-1H-phosphirene aus Phosphaalkinen und Halogencarbenen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1207-1213 
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    ISSN: 0009-2940
    Schlagwort(e): Diazirines ; Phosphaalkynes ; Carbenes ; Phosphirenes ; [2 + 1] Cycloaddition ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Organophosphorus Compounds, 48. - 1-Halogen-1H-phosphirenes from Phosphaalkynes and ChlorocarbenesHalogen-substituted carbenes (7a - i), generated by thermolysis of diazirines (11a-i), add onto phosphaalkynes (8a-c) to form the title compounds (10a-1). Initially formed 2H-phosphirenes (9) could not be detected as their subsequent conversion to the 1H-isomers 10 by a 1,3-halogen shift is very fast. Hydrolysis of 10c,e,g-i and k yields vinylphosphonous acids (17a - e). 1-Chloro-1H-phosphirenes are transformed by nucleophilic substitution into fluoro (10a,c,e → 19a-c), bromo (10c,e → 20a,b), and iodo analogs (10c,e → 21a,b) with the help of silver tetrafluoroborate, trimethylsilyl bromide, and trimethylsilyl iodide, respectively. A crystal structure analysis of 10c is reported.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240538
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  • 90
    Digitale Medien
    Digitale Medien
    Organische Synthesen mit übergangsmetall-Komplexen, 51. 1-Metalla-1,3,5-triene und 1-Metalla-1,3-dien-5-ine von Chrom und Wolfram durch Insertion von Alkinen in M=C- bzw. C=C-Bindungen von 1-Metalla-1,3-dienen bzw. 1-Metalla-1-en-2-inen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1229-1236 
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    ISSN: 0009-2940
    Schlagwort(e): Carbene complexes of chromium and tungsten ; 1-Metalla-1,3,5-trienes ; 1-Metalla-1,3-dien-5-ynes ; Insertion of alkynes into M=C and C=C bonds ; [2 + 2] Cycloaddition reactions of carbene complexes and alkynes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Organic Syntheses via Transition Metal Complexes, 51. - 1-Metalla-1,3,5-trienes and 1-Metalla-1,3-dien-5-ynes of Chromium and Tungsten by Insertion of Alkynes into M=C and C=C Bonds of 1-Metalla-1,3-dienes and 1-Metalla-1-en-3-ynes, respectively1-Metalla-1,3,5-trienes LnM=C(NEt2)-C(Me)—C(OEt)-CH=CHPh (3,4) and LnM=C(OEt)- CH=C(NEt2) - C(Me)=CHPh [5, LnM=Cr(CO)5 (a), W(CO)5 (b)] are obtained for the first time from the corresponding 1-metalla-1,3-dienes LnM=C(OEt) - CH=CHPh (1a, b) under very mild conditions by the insertion of the electron-rich alkyne Et2N-C ≡ C - Me (2) into the M=C and the C=C bonds, respectively, of 1. The chelate complex (6b) and the cyclobutenyl carbene complex 7b are isolated as minor side products. 1-Metalla-1,3-dien-5-ynes LnM=C(NEt2) - C(Me)=C(OEt) - C ≡ CPh [9, 10, LnM=Cr(CO)5 (a), W(CO)5 (b)] are formed with high regio- and stereoselectivity on insertion of 2 into the M=C bonds of 1-metalla-1-en-3-ynes 8. X-ray data are given for the tungsten complex 3b.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240541
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  • 91
    Digitale Medien
    Digitale Medien
    Gas-Phase Thermolysis, 14. On the Isomerization of Dimethyl Carbonate and Its Mono-, Di-, and Trithio Analogs (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1265-1270 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Gas-phase pyrolysis ; Tandem mass spectrometry ; Carbonates ; Alkyl migration ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Gas-phase pyrolysis of dimethyl carbonate and its mono-, di-, and trithio analogs has been performed in the temperature range from 1253 to 1404 K applying the gas phase Curie-point pyrolysis technique. Real-time analyses have been carried out by means of mass-spectrometric techniques. The possible isomerizations of the ester functions have been studied by collisional activation mass spectrometry in combination with appropriate D, 18O, and 34S labeling. It is demonstrated that methyl group migrations can be induced pyrolytically in cases where oxygen-to-oxygen or oxygen-to-sulfur isomerizations are involved; in contrast, sulfur-to-oxygen as well as sulfur-to-sulfur isomerizations apparently do not take place.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240546
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  • 92
    Digitale Medien
    Digitale Medien
    Masthead (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991) 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240601
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  • 93
    Digitale Medien
    Digitale Medien
    Chiral Vinyl Anions for “Carbonyl Umpolung”. Highly Stereoselective Addition of a Novel Enantiomerically Pure Vinyllithium Reagent to Aldehydes (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1379-1395 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Vinyl anions, chiral ; Umpolung ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The vinyllithium reagent 13 and its enantiomer are generated by a bromine/lithium exchange reaction starting from dibromoalkenes 11 and 12, both available from the corresponding enantiomer of alkyl lactate. When 13 is allowed to react with aldehydes or with acetophenone, a highly stereoselective addition to the Re face of the carbonyl compounds occurs to give predominantly the diastereomers 15. Alkenes 25a,c, accessible by another bromine/lithium exchange reaction of 15a,d and subsequent protonation, can be cleaved by ozonolysis followed by reduction to afford carbinols 27a, b in 〉 98% ee. The sequence corresponds to a stereoselective introduction of a methanol d1 synthon (⊖CH2OH) or, as shown by other examples, of acyl and formyl d1 synthons (⊖CRO and ⊕CHO) into prochiral carbonyl compounds. As a consequence, 13 and its enantiomer may be regarded as highly stereoselective reagents for "carbonyl umpolung". A series of further vinyllithium reagents, 38a-g and 54/55, is treated with benzaldehyde, but none of those displays comparable enantiofacial selectivity. The prerequisites to the highly stereoselective reactions of 13 and its enantiomer are briefly discussed.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240612
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  • 94
    Digitale Medien
    Digitale Medien
    Electron Diffraction Study of the Molecular Structure of 1,3-Diphenylpropane-1,2,3-trione (Diphenyl Triketone) (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1411-1414 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Propane-1,2,3-trione, 1,3-diphenyl- ; Electron diffraction ; Gas-crystal structure comparison ; Conformation ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The molecular structure of 1,3-diphenylpropane-1,2,3-trione (diphenyl triketone) has been determined by gas-phase electron diffraction at 130°C nozzle temperature. It has been found that the phenyl rings are nearly coplanar with the adjacent carbonyl groups, and the two Cph-C(O)-C(O)-C(O) dihedral angles are - 129.5 ± 0.8 and - 107.1 ± 0.8° (0° corresponds to the syn form). Bond distances (rg, Å) and bond angles (deg) with estimated total errors are C—H 1.105 ± 0.006, O = C 1.213 ± 0.003, 〈 Cph-Cph〉 1.404± 0.003, Cph-C(O) 1.478 ± 0.005, C(O)-C(O) 1.558 ± 0.004, Cph-C(O)-C(O) 120.0 ± 0.3, Cph—C(O)=O 120.8 ± 0.4, C(O)-C(O)-C(O) 117.3 ± 0.4, Cph-Cph(CO)-Cph 119.8 ± 0.6. Although there is a general agreement between the gas-phase and crystal molecular structures there are some notable differences. One of the benzene rings is slightly turned about the Cph-C(O) axis in the opposite direction in the gas molecule as compared to the crystal. This causes a marked shortening of the O… H intramolecular contact (to 2.18 Á) between the central oxygen and an ortho-hydrogen.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240615
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  • 95
    Digitale Medien
    Digitale Medien
    Ring Fragmentation of Benzotriazol-1-yl Carbanions (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1431-1434 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Proton transfer ; Fragmentation of rings ; Aryllithium ; Carbanions ; Imines ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The title carbanions 1 are shown to lose nitrogen to afford ortho-carbiminophenyl anions 4 which can be protonated by inter- or intramolecular proton transfer or react inter- or intramolecularly with other types of electrophilic center.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240618
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  • 96
    Digitale Medien
    Digitale Medien
    Die Bildungsenthalpie des Allyl- und Methallyl-Radikals (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1453-1460 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Shock tube technique ; Oxygen scavanger ; Heat of formation ; Allyl resonance energy ; Radical disproportionation ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The Heat of Formation of the Allyl and Methallyl RadicalThe decomposition of 1,5-hexadiene (1), 2-methyl-1,5-hexadiene (7), and 2,5-dimethyl-1,5-hexadiene (5) into allyl- (2) and methallyl radicals (6) was studied by means of the shoke tube technique with and without oxygen as scavanger. From these data and from the temperature dependence of the equilibria 1 ⇌ 2 and 5 ⇌ 6, measured between 600 and 800°C, the heat of formation of the allyl (2) and methallyl radical (6) as well as the activation parameters for the recombination and disproportionation of these radicals have been deduced.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240621
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  • 97
    Digitale Medien
    Digitale Medien
    Rotationsbarrieren Vinyl-substituierter Olefine (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1461-1470 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Allyl stabilisation energy ; Calculations, force field ; Rotational barrier, intrinsic ; Gas-phase kinetics ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Rotational Barriers of Vinyl-Substituted OlefinesFor the vinyl-substituted olefines 1 - 14 activation parameters for the geometrical isomerisation have been determined in the gas-phase. By comparison of these barriers with the corresponding ones of the isolated double bonds, each corrected by the contribution of the steric energy to the ground and transition state, a value of 13.5 ± 1.1 kcal mol-1 for the allyl stabilisation energy (ASE), defined as replacement of alkyl by vinyl, has been derived.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240622
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  • 98
    Digitale Medien
    Digitale Medien
    Neue planare π-Systeme, II1) Zur Darstellung und Struktur von Tetrakis(phenylethinyl)ethen (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1471-1475 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Polyacetylenes ; Cross conjugation ; Alkenes, tetraethynyl ; π-Systems, planar ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New Planar π-Systems, II1). - On the Preparation and Structure of Tetrakis(phenylethynyl)etheneThe preparation of tetrakis(phenylethynyl)ethene (1 b) has been repeated. Among various routes to this highly unsaturated cross-conjugated π-system, the dimerization of bromide 2 via the carbene 3 is the most simple one. Full spectroscopic data for 1 b are reported for the first time, as is its X-ray structural analysis at - 95°C.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240623
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  • 99
    Digitale Medien
    Digitale Medien
    Kurzmitteilung/Short Communication Generation and Trapping of Dichlorothioketene (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1485-1487 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Thioketenes ; Flash-vacuum pyrolysis ; Diels-Alder reaction ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Flash-vacuum pyrolysis of 2,4-bis(dichloromethylene)-1,3-dithietane (1) at 820°C furnishes dichlorothioketene (2a) which may be trapped with cyclopentadiene (3) in a [4+2] cycloaddition. The constitution 4a of the product is confirmed by an X-ray structural analysis of the related cycloadduct 4b.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240626
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  • 100
    Digitale Medien
    Digitale Medien
    Bis[2,3-naphthalindiolato(2-)](pyrrolidiniomethyl)silicat-Acetonitril-Solvat: Synthese sowie Kristall- und Molekülstruktur eines zwitterionischen λ5-SpirosilicatsHerrn Professor Ernst Mutschler zum 60. Geburtstag gewidmet. (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1491-1496 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Spirosilicates, zwitterionic ; Bond cleavage, Si - C ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Bis[2,3-naphthalenediolato(2 - )](pyrrolidiniomethyl)silicate Acetonitrile Solvate: Synthesis and Crystal and Molecular Structure of a Zwitterionic λ5-SpirosilicateThe zwitterionic spirocyclic bis[2,3-naphthalenediolato[2-)](pyrrolidiniomethyl)silicate (3) was synthesized and the crystal and molecular structure of its acetonitrile solvate 3 · CH3CN investigated. 3 was prepared by reaction of trimethoxy(pyrrolidinomethyl)silane (8) or dimethoxy(methyl)(pyrrolidinomethyl)silane (8) or dimethoxy(methyl)(pyrrolidinomethyl)silane (9) with 2,3-dihydroxynaphthalene in acetonitrile. Reaction 9 → 3 involves a remarkable Si - C cleavage with formation of CH4. The pentacoordinate silicon atom of 3 · CH3CN is surrounded by 4 oxygen atoms and 1 carbon atom, the latter being in an equatorial position. The coordination polyhedron can be described as a distorted trigonal bipyramid (the structure is displaced by 20.5% from the trigonal bipyramid towards the square pyramid). The crystal lattice of 3·CH3CN contains centrosymmetric dimers of 3, built up by intermolecular N - H … O hydrogen bonds.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19911240702
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