Synthesis and structure of the platinum complexes [Bu4N]+[PtBr5(DMSO)]−, [Ph4P]+[PtBr5(DMSO)]−, and [Ph3(n-Am)P]+[PtBr5(DMSO)

Abstract

The complexes [Bu4N]2+[PtBr6]2− (I), [Ph4P]2+[PtBr6]2− (II), and [Ph3(n-Am)P]2+ (III) are synthesized by the reactions of tetrabutylammonium bromide, tetraphenylphosphonium bromide, and triphenyl(n-amyl)-tetraphenylphosphonium bromide, respectively, with potassium hexabromoplatinate (mole ratio 2: 1). After recrystallization from dimethyl sulfoxide, complexes I, II, and III transform into [Bu4N]+[PtBr5(DMSO)]− (IV), [Ph4P]+[PtBr5(DMSO)]− (V), and [Ph3(n-Am)P]+[PtBr5(DMSO)]− (VI). According to the X-ray diffraction data, the cations of complexes IV–VI have a slightly distorted tetrahedral structure. The N-C and P-C bond lengths are 1.492(7)–1.533(6) and 1.782(10)–1.805(10) A, respectively. The platinum atoms in the mononuclear anions are hexacoordinated. The dimethyl sulfoxide ligands are coordinated with the Pt atom through the sulfur atom (Pt-S 2.3280(18)–2.3389(11) A). The Pt-Br bond lengths are 2.4330(6)–2.4724(6) A.