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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1661-1665 
    ISSN: 1434-1948
    Keywords: Gallium ; Low-valent compounds ; Macrocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrakis[bis(trimethylsilyl)methyl]digallane(4) 1 reacts with dicarboxylic acids like 1,4-benzenedi(methylcarboxylic) acid, 1,4-cyclohexanedicarboxylic acid, 1,6-hexanedicarboxylic acid, and 1,4-butanedicarboxylic acid (adipinic acid) by the release of two equivalents of bis(trimethylsilyl)methane and the retention of the Ga-Ga bond. Products are formed, in which the very short Ga-Ga bonds (237.7 pm on average) are bridged by two carboxylato groups. Two of these moieties are connected in each compound by two spacers (dimethylbenzene, cyclohexane, hexane, or butane) to form macrocyclic compounds with up to 22 atoms in the resultant heteroatomic rings. The dimeric form is also observed in solution. For comparison, the synthesis and structure of the product of the reaction of 1 with 1-adamantanecarboxylic acid is included, which also has the Ga-Ga bond (239.1 pm) bridged by two carboxylato groups.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-1948
    Keywords: Aluminium ; Gallium ; Diazo compounds ; Dimerization ; Coordination modes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lithium trimethylsilyldiazomethanide Li(SiMe3)CN2 reacted with the dialkylaluminium or -gallium halides R2AlCl and R2GaBr [R = CH(SiMe3)2] by the elimination of lithium halide and the formation of the corresponding aluminium or gallium diazo compounds. As shown by a crystal structure determination, the gallium derivative 1 adopts the nitrile imine structure, in which the gallium atom is coordinated by the terminal nitrogen atom of the diazo group. The N-N-C-Si moiety is almost ideally linear with N-N and C-N bond lengths of 125.5 and 115.9 pm on average. In contrast, the diazomethane structure was formed with dialkylaluminium chloride, and the aluminium atom in 2 is attached to the carbon atom of diazomethane. The almost linear N-N-C group (174.1°) has N-N and N-C distances of 120.0 and 126.4 pm, respectively, inverse to that of the gallium derivative. The bonding situations can best be described by the resonance structures R-C≡N+-N--GaR2 for 1 and R2Al-(R)C=N+=N- for 2. The nitrile imine isomer of the aluminium compound could be detected by NMR spectroscopy as a by-product. Both compounds gave dimers in the solid state, a Ga2N2 four-membered heterocycle was formed of 1, while an eight-membered Al2C2N4 heterocycle resulted with 2.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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