Thermal C–P and C–H cleavage in co-ordinated phosphines leading to dinuclear platinum complexes and contrasting reactions with M(PPh3)+ (M = Cu, Ag or Au) and HgCl2†

Abstract

The dinuclear complex [Pt2(µ-PPh2){µ-(o-C6H4PPh2)}(PPh3)2] was prepared by controlled thermolysis of [Pt(C2H4)(PPh3)2] and it contains both a diphenylphosphido and an ortho-metallated triphenylphosphine ligand that bridge the PtI–PtI bond [2.657(1) Å in 3 and 2.677(5) Å in the CH2Cl2 adduct]. Addition of the electrophilic metal reagents [M(PPh3)]+ (M = Cu, Ag or Au) occurs at the Pt–Pt bond, affording [Pt2{µ-M(PPh3)}(µ-PPh2){µ-(o-C6H4PPh2)}(PPh3)2]+ (M = Cu, Ag or Au) whereas selective oxidation by HgCl2 gives the dinuclear platinum(II) complex [Pt2Cl2(µ-PPh2){µ-(o-C6H4PPh2)}(PPh3)2] which is shown to have a “mixed-geometry” structure at the metal centres (square planar and flattened tetrahedral). The new complexes have been analysed by 31P-{1H} and 195Pt NMR spectroscopy and the structures of three complexes have been determined by X-ray diffraction.