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  • 1
    ISSN: 1434-4475
    Keywords: Keywords. Alkali metal organophosphanylamide; Rubidium ; phosphorus bonding; Caesium ; carbon bonding; 18-crown-6 complexes; Caesium-phosphorane-iminato complex.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  The metalation of bis(diphenylphosphanyl)amine, HN(PPh2)2 (5), with RbOtBu in the presence of N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDTA (3)) in toluene surprisingly affords the nearly PMDTA free RbN(PPh2)2 (6a). Recrystallization of 6a from tetrahydrofuran (THF) yields RbN(PPh2)2ċ0.5 THF (6b). Compounds 6a, b crystallize in thin needles; however, these are not suitable for X-ray structure analyses. The reactions of 5 with MOtBu (M=Rb, Cs) in the presence of 18-crown-6 in toluene yield the monomeric, pale yellow rubidium and caesium complexes [Rb(18-crown-6)(N(PPh2)2)] (7) and [Cs(18-crown-6)(N(PPh2)2)] (8), respectively. Allowing to stand a solution of 8 in THF for three months at 20°C results in a cleavage product of 8. This is identified as the dimeric yellow complex [(Cs(18-crown-6))2(μ-N*P(H)Ph2)2]ċTHF (9). The source of the hydrogen atom in the bridging phosphorane iminate anion [N*P(H)Ph2]− is uncertain. Compounds 7–9 are structurally characterized by X-ray analyses. These reveal that [N(PPh2)2]− acts as P-ligating chelate in 7, whereas it coordinates the Cs+ as N-donor as well as η2 C-donor with one phenyl group in 8. No phosphorus coordination is observed in 8. The two caesium cations in 9 are two-fold N-bridged by [N*P(H)Ph2]−. The coordination sphere of each caesium atom is completed by a 18-crown-6 ligand. The solid state 13C NMR spectrum of 8 reveals dynamic phenomena (rotation of the 18-crown-6 ligand). In the solid state 31P spectrum of 8, 31P, 31P–J-coupling is observed between the chemically non-equivalent phosphorus sites (J=390 Hz).
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-4475
    Keywords: Keywords. Paramagnetic; Five-fold coordinated trigonal bipyramidal cobalt(III) complex; Crystal structure; Octaphenyl-tetraphospha-diazene; Imido-tetraphenyl-diphosphinate; Octacarbonyldicobalt.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  The reaction of Co2(CO)8 and Ph2P-N*PPh2-PPh2*N-PPh2 (1) in a molar ratio between 1:1 and 1:3 in toluene always leads to the formation of both the yellow by-product [fac-Co(CO)3(Ph2P-N*PPh2-PPh2*N-PPh2-P,P′)] [Co(CO)4] (4) and the red compound [(Co)2(μ-CO)(CO)4(μ-Ph2P-N-PPh2)2] (5) that has already been characterized by spectroscopic data and X-ray analysis. Whereas 4 is obtained as a precipitate, the red compound 5 stays in solution and reacts in presence of air with the remaining ligand 1 in a non-stoichiometrical reaction to the violet cobalt(III) complex [Co(η1-O-PPh2*N-PPh2*O)(η2-O-PPh2*N-PPh2*O)2] (6). The crystal structure of 6 proves a distorted trigonal bipyramidal coordination of the oxygen atoms at the Co(III) ion. Surprisingly, complex 6 shows an unusual paramagnetism according to four unpaired electrons (5.21±0.04 BM).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    World journal of surgery 8 (1984), S. 399-399 
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Breast cancer research and treatment 4 (1984), S. 79-88 
    ISSN: 1573-7217
    Keywords: breast ; carcinoma ; DNA ; kinetics ; ploidy ; receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The S-phase fraction (SPF) measured by flow cytometry of DNA and the thymidine labeling index (TLI) measured autoradiographically indicate the proportion of carcinoma cells currently synthesizing DNA and reflect the rate of proliferation. The TLI and SPF are lognormally distributed. The median TLI performed to maximize precursor uptake is near 5% (5 labeled carcinoma cells per 100), the mean near 7%, and the range from less than 1% to near 40%. Corresponding values for the SPF measured by DNA flow cytometry are slightly higher when appropriate measures are taken to reduce background debris counts and other artefacts. Residual elevation of SPF above TLI may result from S-phase arrested cells. Flow cytometric histograms show that clearly aneuploid cell lines exist in 50–80% of primary breast carcinomas. Aneuploid breast carcinomas have higher mean TLI than diploid breast carcinomas, and therefore proliferate more rapidly. They also more frequently lack estrogen receptor (ER). Carcinomas with minimal nuclear anaplasia, particularly those of tubular, mucinous, infiltrating lobular and adenocystic types have low TLI and SPF, whereas carcinomas with highly anaplastic nuclei, including medullary carcinomas, have high TLI and SPF. TLI and SPF correlate inversely with ER and PgR content, have no relationship to axillary lymph nodal status, and have a weak positive correlation with tumor size and a weak negative correlation with age. High TLI predicts a high risk of early relapse after primary therapy for both node-negative and node-positive carcinomas. Carcinomas that produce brain metastases have particularly high TLI. Current evidence suggests that high SPF and aneuploidy may prove to have prognostic significance like TLI.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1972-1988 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Degree of Aggregation of Organolithium Compounds by Means of Cryoscopy in TetrahydrofuranThe association behaviour of alkyl-, aryl- and alkinyl-lithium compounds as well as of lithium enolates and chiral lithium azaenolates is determined from freezing-point depression values in dilute tetrahydrofuran solutions at -108°C. Compared toX-ray-crystallographic data (lithiated methyldithiane, phenyllithium, lithio derivatives of a ketone, carboxylic amide and -ester, and a diketopiperazine-bislactim-ether), desaggregation is found under these conditions. The structures determined by 13C-NMR spectroscopy for BuLi, lithiophenylacetylene and (t-butyl)lithioacetylene are confirmed. The dilithio salt of a carboxylic acid is polymeric, a chiral lithio-hydrazone and a chiral lithio-oxazolidine are monomeric and dimeric, respectively. Lithium diisopropylamide is a monomer-dimer equilibrium mixture. The apparatus described permits both synthesis and measurement of the reactive species under inert atmosphere conditions in the same vessel.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0009-2940
    Keywords: Alkali metal organophosphanylamide ; Carbon-potassium bonding ; Phosphazane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metalation of bis(diphenylphosphanyl)amine [HN-(PPh2)2,1 with KOtBu at 95°C in toluene affords a pale yellow precipitate of potassium bis(diphenylphosphanyl)amide (3a). On addition of liquid N,N,N′,N“,N“-pentamethyldiethylenetriamine (PMDTA, 4) the precipitate dissolves in toluene at 115°C to give a yellow solution, from which yellow-green blocks of [(Ph2P)2NK·PMDTA] (3b) are obtained. X-ray analysis reveals that the coordination sphere of potassium consists of the chelating triamine ligand and [N(PPh2)2]- as N-donor as well as η1 and η2 C-donor with two phenyl fragments. No phosphorus coordination of [N(PPh2)2]- is observed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 1154-1173 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Fulvenes with Inverse Ring Polarization, 10. Electron Rich HeptafulvenesThe synthesis and structural properties of the electron rich heptafulvenes 3a - f are described. The compounds 3 have electron donor substituents at C-8. In the case of 3f NMR-spectroscopy revealed the presence of a boat conformation with bond alternation. HMO-calculations showed that, depending on the electron donor properties, the C-8 substituents lead to a characteristic “HOMO-LUMO-GAP-NARROWING”.  -  The new compounds 3a - f have been synthesized either from derivatives of 1,3,5-cycloheptatriene-7-carboxaldehyde or from cycloheptatriene-7-carboxylic acid.
    Notes: Synthesen und Struktureigenschaften der elektronenreichen Heptafulvene 3a - f werden beschrieben. Die Verbindungen 3 haben Donorsubstituenten an C-8. Am Beispiel des Bis(dimethylamino)heptafulvens 3f wurde mit 1H-NMR gezeigt, daß die Bootkonformation vorliegt und die C — C-Bindungen Bindungsalternanz zeigen. Zur weiteren Charakterisierung des π-Systems wurde das HMO-Modell verwendet: Charakteristisch ist insbesondere die Verringerung der Energielücke zwischen den Grenzorbitalen durch die Donorsubstituenten an C-8  -  Die Verbindungen 3a - f wurden entweder aus Derivaten des 1,3,5-Cycloheptatrien-7-carboxaldehyds oder der Cycloheptatrien-7-carbonsäure synthetisiert.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 809-826 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Highly Unsaturated Radical Cations: Regio- und Stereochemistry of the Oxidative Dimerizations of HeptafulvenesThe oxidative dimerizations of heptafulvenes 3 yield bicycloheptatrienyl compounds 4, 5, 7, and 8 in single electron transfer reactions (SET). The C - C bond formation proceeds exclusively at the less hindered ring carbons. In all cases mixtures of regio- and stereoisomers are formed. Steric and electronic effects of the substituents influence the product distribution. The diester meso(u)-4a is thermically labile and rearranges to a complex mixture of bicycloheptatrienyls. The bicycloheptatrienyls are further characterized by cycloaddition reactions with 4-methyl-4H-1,2,4-triazole-3,5-dione (12a), leading to homobarrelenes. - The crystal structure of meso(u)-4a is determined by an X-ray analysis.
    Notes: Die oxidative Dimerisierung der Heptafulvene 3 führt zu Bicycloheptatrienyl-Verbindungen 4, 5, 7 und 8 über radikalische Zwischenstufen. Die C - C-Verknüpfung erfolgt an den sterisch weniger gehinderten Kohlenstoffen. Die Substituenten beeinflussen die Regio- und Stereoselektivität. Die thermische Labilität der Bicycloheptatrienyl-Verbindungen wird am Beispiel des Diesters meso (u)-4a gezeigt. Die Umlagerungsreaktion führt zu einer Vielzahl von Isomeren. Chemisch werden die Bicycloheptatrienyl-Verbindungen durch Addition von 4-Methyl-4H-1,2,4-triazol-2,5-dion (12a) charakterisiert, die zu Homobarrelenen führt. - Die Kristallstruktur von meso(u)-4a wird durch eine Röntgenstrukturanalyse bestimmt.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 1777-1786 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cross Conjugated Enolates: Structure Characterization of Two Lithium HeptafulvenolatesWhen deprotonated, N,N-dimethylcycloheptatriene-7-carboxamide (2a) and cycloheptatriene-7-carboxylic acid (2c) yield the amide anion 4a and the acid dianion 4c. Due to the NMR spectra, 4a and c show in the range 600-700 nm three and two signals, respectively. The spectra are temperature and solvent dependent. The THF-solution of 4c is paramagnetic. The structures of the organolithium compounds are discussed.
    Notes: Die bei der Deprotonierung von N,N-Dimethylcycloheptatrien-7-carboxamid (2a) und Cycloheptatrien-7-carbonsäure (2c) entstehende Lithiumverbindung 4a und Dilithiumverbindung 4c werden spektroskopisch charakterisiert. 4a und c sind Heptafulvene, d. h. das Lithium ist am Sauerstoff lokalisiert. Die Elektronenspektren von 4a und c im Bereich 600-700 nm zeigen drei bzw. zwei Banden, deren Intensitäten von der Lösungsmittelzusammensetzung und der Temperatur abhängen. Die Lösung von 4c in Tetrahydrofuran ist paramagnetisch. Die Strukturen der lihiumorganischen Verbindungen werden diskutiert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0947-6539
    Keywords: clathrates ; cryptates ; helicates ; selfassembly ; zinc complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structures of the hitherto unknown bis(double helicate) 10 and its cryptatoclathrate (10)2·2THF were unequivocally determined by X-ray diffraction. Bis(double helicate) 10 is formed in a one-pot synthesis starting from CH-acidic bis (tetrazolylmethyl ketone) 9 and Zn(OAc)2. The formation of racemic, homochiral 10 from [Zn2L32] fragments, which are formed in a self-assembly process, is governed by chiral self-recognition. According to NMR studies only 10 is present in solution. 13C CP/MAS NMR spectroscopy and X-ray analysis confirm aggregation of 10 with two molecules of THF to yield the inclusion compound (10)2·2 THF in the solid state.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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