Synthesis,structure and decomposition of the digermane Ph 3 GeGePh 2 H

Abstract

Reaction of Ge₂Ph₆ (1) with trichloroacetic acid at 95°C in toluene for 4 days yields a mixture of the two digermanes (Cl₃CCOO)Ph₂GeGePh₂(OOCCCl₃) (2) and Ph₃GeGePh₂(OOCCCl₃) (3) that are converted to a mixture of ClPh₂GeGePh₂Cl (4) and Ph₃GeGePh₂Cl (5) using ethereal HCl. Treatment of the mixture of 4 and 5 with LiAlH₄ affords the two digermanes HPh₂GeGePh₂H (6) and Ph₃GeGePh₂H (7). The digermane 7 was separated from 6 by crystallization and its X-ray crystal structure was determined. Digermane 7 crystallizes in two different morphologies, where one contains three independent molecules in the unit cell (7a) and the other contains only one independent molecule (7b). The Ge – Ge bond distances in these two structures are 2.4234(7) Å (average) in 7a and 2.4213(5) Å in 7b. Compound 7 is thermally unstable and releases Ph₃GeH upon heating this material to 200°C in the solid state, with concomitant formation of the germylene Ph₂Ge: that polymerizes.