Vinyl derivatives of silicon, germanium, and tin

Abstract

Reaction of MCl₄, (M = Si, Ge, or Sn) with vinylmagnesium bromide yields M(CH:CH₂)₄ as the major product for M = Si or Sn, but Ge(CH:CH₂)₄ and Ge₂(CH:CH₂)₆ are formed in comparable yield. Isolation of metal–metal bonded derivatives has allowed characterization by i.r., Raman, ¹H n.m.r., and mass spectroscopy of the compounds M₂(CH:CH₂)₆(M = Si, Ge, or Sn). The mass spectra of tetravinyl-silane, -germane, and -stannane are reported and discussed in terms of the effect on fragmentation patterns of M–C bond strength. Tetravinylgermane is chemically very unreactive, but with dibromine in an equimolar ratio one Ge–C bond is cleaved to give GeBr(CH:CH₂)₃ while with dichlorine addition occurs forming Ge(CHCl·CH₂Cl)₄.