Oxidation of a Pt2(µ-SO2) moiety to µ-SO3 and the crystal structure of [Pt2(µ-SO3)(µ-SO2)(C8H12)2]

Abstract

Bis(cyclo-octa-1,5-diene)platinum(0) as a solid has been found to react immediately with SO₂giving [Pt₂(µ-SO₂)₂(C₈H₁₂)₂], (1). N.m.r. spectroscopy reveals that the two C₈H₁₂ ligands in the dimer (1) have three co-ordinated olefinic groups with the remaining one not co-ordinated. The presence of µ-SO₂ ligands is consistent with the i.r. spectrum. Solutions of complex (1) are oxidized slowly by atmospheric O₂to give the novel µ-SO₃ complex [Pt₂(µ-SO₃)(µ-SO₂)(C₈H₁₂)₂], (2). Complex (2) was characterized by single-crystal X-ray crystallography and consists of two distorted square-planar platinum(II) fragments held together by a bridging SO₂^2– anion and a bridging SO₃^2– anion. The bond parameters at both Pt atoms indicate a square-planar co-ordination geometry and a value of 20.1° is calculated for the dihedral angle between the two square-planar fragments. The µ-SO₂ ligand is σ-bonded to both Pt atoms through the S atom while the µ-SO₃ ligand is σ-bonded to one Pt atom by the S atom and to the other metal via an O atom. The two Pt, the two S, and the O atoms form a puckered five-membered ring.