Synthesis, structure and decomposition of the digermane Ph3GeGePh2H

Abstract

Reaction of Ge 2 Ph 6 (1) with trichloroacetic acid at 95 • C in toluene for 4 days yields a mixture of the two digermanes (Cl 3 CCOO)Ph 2 GeGePh 2 (OOCCCl 3 ) (2) and Ph 3 GeGePh 2 (OOCCCl 3 ) (3) that are converted to a mixture of ClPh 2 GeGePh 2 Cl (4) and Ph 3 GeGePh 2 Cl (5) using ethereal HCl. Treatment of the mixture of 4 and 5 with LiAlH 4 affords the two digermanes HPh 2 GeGePh 2 H (6) and Ph 3 GeGePh 2 H (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 Ph 3 GeH upon heating this material to 200 • C in the solid state, with concomitant formation of the germylene Ph 2 Ge: that polymerizes.