Crystal and molecular structures of some tri-aryltin isothiocyanates (Ar3SnNCS; Ar = C6H5, p-CH3C6H4, o-CH3C6H4, o-CH3OC6H4) and of the adduct hexamethylphosphoramide(N-miocyanato) tris (o-tolyl) tin

Article abstract of DOI:10.1016/s0020-1693(98)00190-x

Full crystal structures are reported for several tri-aryltin isothiocyanates, Ar₃SnNCS [Ar = Ph (A), p-Tol (B), o-Tol (C), o-CH₃OC₆H₄ (D)], as well for the adduct (o-Tol)₃SnNCS·HMPA (E) (HMPA = hexamethylphosphoramide). Compound B like A has bridging thiocyanates with five-coordinate tin but C and D are the first accurately characterised monomeric Ar₃SnNCS, with four-coordinate tin. The adduct has unambiguously five-coordinate tin even with the ortho-methyls present. The small but significant changes in thiocyanate bond lengths correlate with changes in the geometry at tin, and these changes confirm that ν(CN) values do indeed accurately monitor trends in modes of thiocyanate bonding when involving coordination to the same type of Lewis acid environment.