Pyrolyses of diaryl(phosphine)platinum(II) complexes: effect of added phosphines

Abstract

The presence of additional tertiary phosphine, L or P–P, promotes the thermal reductive elimination of biaryl, R₂, from cis-[PtR₂L₂] or [PtR₂(P–P)](R = Ph or C₆H₄Me-4; L = PPh₃; P–P = Ph₂PC₂H₄PPh₂ or Ph₂PCH₂PPh₂). Secondary decomposition modes, which operate in the pyrolysis of the platinum complexes themselves, are largely suppressed, and the primary metal-containing products are [PtL₃] or [Pt(P–P)₂]. The platinum(O) complexes themselves undergo thermolysis at elevated temperatures, and the products from the chelating phosphine derivatives indicate a reaction route involving insertion of Pt⁰ into alkyl–phosphorus bonds. There is evidence that in some cases added phosphine exchanges with that already in the complex before thermolysis begins.