Characterisation of bis-methylgermanium and bis-methylsilicon carbodi-imides and their reactivity with protic reagents

Abstract

Bismethylgermanium and bismethylsilicon carbodi-imides have been prepared in high yield by halide metathesis reactions with lead(II), silver(I), or silicon(IV) species. The new derivatives in the series of general formula (Me_nH_{3 –n}MN:)₂C (MSi or Ge; n= 1, 2 or 3) have been characterised by ¹H n.m.r., i.r., and Raman spectroscopy as well as mass spectrometry and cleavage reactions. The utility of the germanium carbodi-imides as synthetic intermediates is shown by ready cleavage of the Ge–N bond by Group VI and other protic species leading to the formation of chalcogeno-germanes and related derivatives of the type (Me_nH_{3 –n}Ge)₂E (E = O, S, Se or Te) and Me_n H_{3 –n} GeSR (R = Me, Bu^t, ph, MeC(O), or –CH₂CH₂–). Comprative studies show that in the silicon carbodi-imides the Si–N bond is not susceptible to protolysis by the heavier chalcogenols.