Synthesis, solution and magic angle spinning tin-119 nuclear magnetic resonance studies and crystal structures of dithioether complexes of tin(IV) halides

Abstract

The compounds SnX₄ reacted with 1 molar equivalent of dithioether, L–L, in dry CHCl₃ solution to give the six-co-ordinate species [SnX₄(L–L)][X = Cl, L–L = MeS(CH₂)_nSMe, o-C₆H₄(SMe)₂ or PhS(CH₂)_nSPh (n= 2 or 3); X = Br, L–L = MeS(CH₂)_nSMe or o-C₆H₄(SMe)₂] in high yield as white or pale yellow powdered solids. Using SnBr₄ and PhS(CH₂)_nSPh or SnI₄ with MeS(CH₂)_nSMe did not produce isolable products, although solution ¹¹⁹Sn-{¹H} NMR spectroscopy provided evidence for their existence at low temperatures. X-Ray structural studies on [SnCl₄{MeS(CH₂)₂SMe}], [SnCl₄{MeS(CH₂)₃SMe}], [SnCl₄{o-C₆H₄(SMe)₂}], [SnCl₄{PhS(CH₂)₃SPh}] and [SnBr₄{MeS(CH₂)₃SMe}] confirmed an S₂X₄ donor set with the dithioether acting as a bidentate chelate. Variable-temperature solution ¹H and ¹¹⁹Sn-{¹H} NMR spectroscopic studies showed that the complexes are extremely labile and ligand dissociation and pyramidal inversion are fast except at low temperatures. Magic angle spinning ¹¹⁹Sn NMR data for [SnCl₄(L–L)] are reported. The crystal structure of cis-[SnI₄{MeS(O)(CH₂)₃SMe}₂], obtained as a decomposition product from the SnI₄–MeS(CH₂)₃SMe reaction, shows monodentate sulfoxide (O) co-ordination.