STUDIES OF GERMANIUM-TRANSITION METAL BOND FORMATION

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Hexamethyldigermanes reacted with various alkynes in the presence of platinum complexes (0) at 120℃ to afford Z-bis(germyl)ethenes in moderate to good yields. Bis(germyl)platinum complexes (II) having various tertiary phosphine ligands have been prepared as a model of a key intermediate in the catalytic bis-germylation of alkynes and their structures have been established by spectroscopic methods and X-ray crystallography. Bis(germyl)platinum complexes reacted with phenylacctylene to give the corresponding insertion complexes, germyl(germylvinyl)platinum species, whose structures have been determined by spectroscopic and X-ray analysis. Germyl(germylvinyl)platinum complexes were found to liberate a bis-germylation product of the alkyne on heating. The result supports the mechanism involving oxidative addition of a digermane to Pt(0) complex, insertion of alkynes into one of the two Pt-Ge bonds to give a germyl(germylvinyl)platinum species, and reductive elimination of the bis-germylation product of the alkynes.