Molecular structures of the main group 4 metal(II) bis(trimethylsilyl)-amides M[N(SiMe3)2]2 in the crystal (X-ray) and vapour (gas-phase electron diffraction)

The group 4 metal(II) bis(trimethylsilyl)amides, M[N(SiMe3)2]2, are V-shaped monomers both in the crystal (M = Sn or Pb) at 140 K and the vapour (M = Ge, Sn, or Pb) at ca. 380 K, with ∠NMN in the vapour being 101(1.5), 96, or 91(2)° for M = Ge, Sn, or Pb respectively [but 104.7(2)(M = Sn) or 103.6(7)°(M = Pb) in the solid].