Synthesis and characterization of novel penta- and hexacoordinated sulfur-containing spirocyclic tin(IV) complexes

Article abstract of DOI:10.1021/ic00134a030

Reactions of bis(toluene-3,4-dithiolato)tin(IV), Sn(TDT)₂ (2), with the bases dimethyl sulfoxide (Me₂SO), hexamethylphosphoramide (HMPA), and triphenylphosphine oxide (Ph₃PO) yield hexacoordinated spirocyclic neutral adducts. Hydroxide ion with 2 gives a hexacoordinated dianionic product. Various reactions of 2 with a variety of halide salts yield new spirocyclic pentacoordinated monoanionic compounds, [XSn(TDT)₂]^-[R₄M]⁺ (M = N, P, As). Large cations tend to stabilize the complexes. Reversible color changes take place on heating the pentacoordinated derivatives. The substances are characterized by ¹H NMR and tin-119m M?ssbauer spectroscopy. The isomer shift of the monohalo anions shows a decrease with halogen electronegativity consistent with electron withdrawal at the tin center. The quadrupole splitting (QS) values are in the range 1.06-1.44 mm s^-1 for the pentacoordinated monoanions investigated. These low values, lower than many QS values for tetracoordinate tin(IV) compounds, are associated with rectangular-pyramidal geometries around tin, as found by X-ray diffraction studies on representative members.