Zwitterionic λ⁵Si-Silicates with anSiS₄C orSiS₂O₂C Skeleton, Compounds Containing a Square-Pyramidal or Trigonal-Bipyramidal Si-Coordination Polyhedron

Treatment of [2-(dimethylamino)phenyl]-silane (8) with 2 molar equivs of benzene- 1,2-dithiol or 2-mercuptoacetic acid yields bis[benzene-1,2-dithiolato(2-)][2-(dimethylammonio)phenyl]silicate (6) and [2-(dimethylammonio)phenyl]bis[2-mercaptoethanoato(2-)- O,S]silicate (7), respectively. The zwitterionic lambda(5)Si- silicates were structurally characterized by solid-state NMR spectroscopy (C-13, N-15, Si-29) and single-crystal X-ray diffraction. Compound 6 is the first zwitterionic Si-silicate with Si-S bonds that contains a square-pyramidal Si-coordination polyhedron.