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  • 1
    ISSN: 0009-2940
    Keywords: α-Diazocarbonyl compounds ; Cobalt complexes ; [2 + 3] Cycloaddition ; Cobaltaheterocycles five-membered ; Protonation of exocyclic C=NR bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloaddition Reactions of Organometallic Complexes, XI. - Cobaltaheterocycles by [2 + 3) Cycloaddition of α-Keto Carbenes to Co - CO and Co - CNR BondsThe reactions of the carbonyl(cyclopentadienyl) and (cyclopentadienyl)isocyanidecobalt complexes C5H5Co(CO)(PR3) (1-4) and C5H5Co(CNR)(PMe3) (5, 6) with α-diazocarbonyl compounds R1C(O)C(N2)R2 lead to the formation of the cobaltaheterocycles C5H5(PR3)(=O) (7-12) and C5H5(PMe3)(=NR) (13-16), respectively. For R = (S)-CH(Me)Ph a mixture of diastereoisomers RCoSCoSc is obtained. The complexes 13-16 react with HBF4 in ether to give the cations [C5H5(PMe3)-(NHR)]+ (17-20, with BF4 as anion), which on treatment with base regenerate the uncharged cobaltaheterocycles. The X-ray structural analysis of 19-RCoSc reveals the presence of a planar CoOC3 five-membered ring which presumably is formed by a [2+3] cycloaddition of an α-ketocarbene to the Co—CNR bond.
    Additional Material: 1 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 707-712 
    ISSN: 0009-2940
    Keywords: Osmium mesitylene complexes ; Os - R bonds, formation of ; Osmium aryl hydrido compounds ; Cyclohexene, generation from C6H11MgX ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of [(Mes)Os(CO)Cl2] (3) with PhLi in benzene gives the diphenylosmium compound [(Mes)OsPh2(CO)] (6) whereas with PhMgBr [(Mes)OsPh(CO)Br] (7) is obtained. Treatment of 3 with TolMgBr in benzene or ether affords almost exclusively the monoaryl complex [(Mes)OsTol(CO)Br] (8). Compound 3 reacts with C6H11MgCl to give both [(Mes)Os(C6H11)2(CO)] (9) and [(Mes)Os(C6H10)(CO)] (10) in 60 and 30% yield, respectively. With C6H11MgBr, complex 10 is mainly obtained. Reaction of 7 and 8 with Na/Hg in THF/EtOH gives nearly quantitatively the arylhydridoosmium complexes [(Mes)Os-C6H4R(CO)H] (14, 15). The analogous hydrido methyl compound [(Mes)OsCH3(CO)H] (13) reacts with CCl4 to produce [(Mes)OsCH3(CO)Cl] (17), which is not accessible from 3 and LiCH3 or CH3MgX. The X-ray structure analysis of 10 reveals that the cyclohexene is coordinated in the endo configuration.
    Additional Material: 1 Ill.
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  • 3
    ISSN: 0009-2940
    Keywords: Cyclopentadienyl anion, substituted ; Cobalt complexes ; Rhodium complexes ; Iridium complexes ; Bis(cyclopentadienyl)methane dianion as bridging ligand ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(cyclopentadienyl)methane-bridged Dinuclear Complexes, V[1]. - Heteronuclear Co/Rh-, Co/Ir-, Rh/Ir-, and Ti/Ir Complexes with the Bis(cyclopentadienyl)methane Dianion as Bridging Ligand*The lithium and sodium salts of the [C5H5CH2C5H4]- anion, 1 and 2, react with [Co(CO)4I], [Rh(CO)2Cl]2, and [Ir(CO)3Cl]n to give predominantly the mononuclear complexes [(C5H5-CH2C5H4)M(CO)2] (3, 5, 7) together with small amounts of the dinuclear compounds [CH2(C5H4)2][M(CO)2]2 (4, 6, 8). The 1H- and 13C-NMR spectra of 3, 5, and 7 prove that the CH2C5H5 substituent is linked to the π-bonded ring in two isomeric forms. Metalation of 5 and 7 with nBuLi affords the lithiated derivatives 9 and 10 from which on reaction with [Co(CO)4I], [Rh(CO)2Cl]2, and [C5H5TiCl3] the heteronuclear complexes [CH2(C5H4)2][M(CO)2][M′(CO)2] (11-13) and [CH2(C5H4)2]-[Ir(CO)2][C5H5TiCl2] (17) are obtained. Photolysis of 11 and 12 leads almost quantitatively to the formation of the CO-bridged compounds [CH2(C5H4)2][M(CO)(μ-CO)M′(CO)] (14, 15). According to an X-ray crystal structure analysis the Co/Rh complex 14 is isostructural to [CH2(C5H4)2][Rh2(CO)2(μ-CO)] (16).
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 839-841 
    ISSN: 0009-2940
    Keywords: Rhodium complexes ; Molecular structure ; square-planar ; Hydrogenation reactions ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(triisopropylphosphane)rhodium Dichloride: Formation and StructureThe mononuclear rhodium(II) complex trans-[RhCl2(PiPr3)2] (4) has been obtained from [RhCl(PiPr3)2]n (3) and CCl4. The X-ray structural analysis of 4 reveals a square-planar coordination at the metal center. Reaction of 4 with H2 leads to the formation of the monohydrido compound [RhHCl2(PiPr3)2] (7) which on further treatment with H2 in the presence of Na[N(SiMe3)2] gives the dihydride [RhH2Cl(PiPr3)2] (8). Complex 7 has also been prepared from 3 and HCl.
    Additional Material: 1 Ill.
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  • 5
    ISSN: 0009-2940
    Keywords: Ketenimines ; Cobalt complexes ; Bond formation, C-C ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloaddition Reactions of Organometallic Complexes, XII1). - Ketenimines from Isocyanides and Diazoalkanes: A New Cobalt-Assisted C-C Bond Forming ReactionThe compounds C5H5Co(CNR)(PMe3) (1-3) react with diaryl-diazomethanes (X)(Y)CN2 to give the C,C-bound ketenimine cobalt complexes C5H5Co[η2-C,C-RN=C=CXY] (PMe3) (4-9), while the reaction of 1-3 with 9-diazofluorene leads to the formation of N,C-bound ketenimine complexes C5H5Co[η2-N,C-RN=C=C(C12H8)](PMe3) (11-13). The different bonding modes of the ketenimine ligands in 4-9 and 11-13, indicated already by the significantly different spectroscopic data, are shown by the X-ray structural analysis of 9-RCoSC (R = CHMePh; X and Y = 4-ClC6H4) and 12 (R = C6H11). On treatment of compounds 4, 6-9, 11, and 13 with an equimolar amount of iodine, free ketenimines are generated. The by-product C5H5Co(PMe3)I2 can be transformed into the starting materials 1-3 in two steps via the cations [C5H5Co(CNR)-(PMe3)I]+ as intermediates.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1121-1125 
    ISSN: 0009-2940
    Keywords: Osmium complexes ; 1-Alkynols, reactions with ; Carbenes, cyclic, five-membered ; Vinyl ethers, metal-bound ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (Benzene)osmium(II) Complexes with Cyclic Oxycarbenes and Vinyl Ethers as LigandsThe compounds [C6H6Os(PR3)]2] (5, 6) react with 1-alkynols HC≡CCH2CHR'OH in the presence of AgPF6 to give cyclic oxycarbene complexes (7-9) in almost quantitative yields. During the reaction vinylideneosmium intermediates are probably formed. Deprotonation of 7-9 with NaH affords the vinyl ether complexes (10 - 12). Reaction of 10 with methyl triflate (in the presence of NaH) leads to the formation of (13). The crystal and molecular structure of the oxycarbene complex 7 has been determined.
    Additional Material: 1 Ill.
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  • 7
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis, characterization and liquid-crystalline (LC) properties of polysiloxanes containing side chains with terminal 2-fluorenyl groups and various lengths of spacers is reported. The polymers which have no flexible tail segment exhibit two smectic mesophases (SA and SE), as confirmed by polarizing microscopy, differential scanning calorimetry (DSC) and X-ray investigations; a nematic mesophase was not found. The clearing temperatures of the polymers (in the range between 120 and 170°C) are generally 70-80°C higher than the melting temperatures of the non-liquid-crystalline precursors with a terminal vinyl group. With increasing spacer length the less ordered SA phase is favoured and has been found in a temperature range of up to 100 K width. For polymers with an SE phase no glass transition was detectable with DSC. The synthesized polymers are examples of the strong potential of the fluorene core to form LC phases without further structural stabilization.
    Additional Material: 3 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 3107-3113 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis of the liquid-crystalline polysiloxanes, 4a, 4b, 5a, 5b with 2,7-disubstituted fluorene units and of the related liquid-crystalline model compounds 2 and 3 is reported. Polymers 4a, 4b, 5a, 5b were prepared from monomers 2 and 3, respectively, and poly(hydrogenmethyl-siloxane) (PHMS) in a polymer-analogous reaction. The liquid-crystalline properties of the polymers and the corresponding low-molecular-weight compounds 2 and 3 were characterized by differential scanning calorimetry (DSC) and polarizing microscopy. Both compounds 2 and 3 show a smectic A and a smectic E mesophase, and the resulting polysiloxanes also exhibit smectic A- and smectic E-like textures but no nematic phase. The clearing point of the polymers is on the average by 100°C higher than that found for the low-molecular-weight compounds.
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  • 9
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Theory and Simulations 2 (1993), S. 361-369 
    ISSN: 1018-5054
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The formation of polymer networks (gelation process) was studied by a numerical simulation of a lattice spin model with 3 states, which allows the representation of simple diffusion and aggregation processes. Near the percolation threshold, pc, the same critical exponents were detected as in the usual diffusion-free classical percolation theory. Only non-universal values (for example pc) show a significant dependence on the ratio between diffusion and reaction constants.
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  • 10
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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