Unexpected substitution reactions of bis(phosphine)platinum ethene complexes

Abstract

Reaction of [Pt(C₂H₄)(PR₃)₂](R = Ph or C₆H₄Me-4) with moderately bulky phosphines at low temperatures did not give the expected tris- or tetrakis-phosphine complexes. Instead, mixed-phosphine complexes of the type [Pt(C₂H₄)(PR₃)(PR′₃)](R′= C₆H₁₁, C₆H₄OMe-4, C₆H₄OMe-2, C₆H₄Me-4 or CH₂Ph) were formed. With less bulky phosphines, chelating diphosphines or phosphites, mixed tetrakis complexes, many of them prone to disproportionation, were formed. The complexes were characterised by ³¹P and ¹⁹⁵Pt NMR spectroscopy in solution.