Synthesis and crystal structures of platinum (II) complexes with phosphine sulfide: cis-Dichloro[dimethylsulfoxide](triphenylphosphine sulfide) platinum (II) and (−)-cis-dichloro[(S)-methyl-p-tolylsulfoxide](triphenylphosphine sulfide) platinum (II)

The addition of triphenylphosphine sulfide (Ph3PS) to bis-sulfoxide platinum (II) complexes [Pt(Me2SO)2Cl2] and (−)-[Pt(Me-p-TolSO)2Cl2] yields mixed ligand complexes [Pt(Ph3PS)(Me2SO)Cl2] (1) and (−)-[Pt(Ph3PS)(Me-p-TolSO)Cl2] (2), which are effective catalysts for hydrosilylation reaction. These mixed-ligand complexes were obtained in crystal state and analyzed by X-ray diffraction, 1H, 31P and 195Pt NMR; 2 was also studied by circular dichroism spectroscopy. Both complexes exist in CDCl3 solution as a dynamic equilibrium of two geometric isomers with an approximate 1:10 ratio, but only cis-isomer is obtained on crystallization. The X-ray structures of the complexes have classical geometry, and phosphine sulfide and sulfoxides are coordinated via sulfur. The new structural data for simple platinum–Ph3PS coordination bond, unaffected by chelation or bridging, were evaluated. The lengths of this bond are 2.300(4) Å in 1 and 2.305(3) Å in 2, respectively. PtSP angle equals 105.7(2)° in 1 and 104.05(13)° in 2, the PtSP plane is almost perpendicular to the coordination plane. The static trans-influence of Ph3PS is estimated to be strong and close to that of S-coordinated Me2SO. The complex 2 exhibits strong circular dichroism at a wavelength below 330 nm, caused both by inherent Me-p-TolSO stereogenic center and induced asymmetry of Ph3PS.