1:2 Trimethylphosphine Complexes of the Group IV Tetrahalides, trans-MX4•2P(CH3)3 and trans-MX4•2P(CD3)3 (where M = Si, Ge, or Sn; X = Cl or Br); Assignment of Metal–Phosphorus modes

The vibrational spectra of some 1:2 trimethylphosphine adducts of the group IV tetrahalides, which contain ligands in a trans configuration, are examined in detail using perdeutero-trimethylphosphine to facilitate the assignment of all metal–halogen and metal–phosphorus stretching modes. Preparation of SiCl4•2PMe3 with a 1:1 mixture of P(CH3)3 and P(CD3)3 enables an almost unambiguous assignment of the spectrum of this adduct. Normal coordinate calculations for all adducts are reported.