Synthesis, structure and chemical transformations of ethynylgermatranes

Article abstract of DOI:10.1002/ejic.200300236

Ethynylgermatranes have been prepared from monosubstituted acetylenes by a three-step synthesis without isolation of the hydrolytically unstable intermediate chlorogermanes and ethoxygermanes. Boiling an equimolar mixture of tetrachlorogermane Cl₄Ge, acetylene RC≡CH and triethylamine in hexane leads to germylation of the C_sp-H bond and the formation of ethynyl-substituted trichlorogermanes. Subsequent alkoxylation of chlorogermanes by ethanol in the presence of triethylamine affords triethoxygermanes that then take part in transalkoxylation with triethanolamine to give ethynylgermatranes. The molecular structures of all ethynylgermatranes and the hexacarbonyldicobalt complex of 1-heptynylgermatrane have been determined by X-ray crystallography. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.