Reaction of the Carbodiphosphorane Ph3PCPPh3 with Platinum(II) and -(0) Compounds:  Platinum Induced Activation of C−H Bonds

The complex [(cod)PtI2] (cod = 1,5-cyclooctadiene) reacts with 3 equiv of the hexaphenylcarbodiphosphorane Ph3PCPPh3 (1) in THF solution to give the novel Pt(II) complex [(η3-C8H11)Pt(C6H4PPh2CPPh3)] (2) along with the salt [HC(PPh3)2]I. In addition to the coordination of the ylidic carbon atom at the Pt atom, 2 contains two further Pt−C σ bonds originating from H to Pt exchange in the ortho position of one phenyl group of the carbodiphosphorane ligand and in the former cod ligand. The resulting C8H11 moiety is coordinated to the Pt atom in an η3 manner via a double bond and a σ bond and contains a further uncoordinated double bond. From a 1:1 reaction mixture in toluene/CH2Cl2 the majority of the crystals consist of the salt [HC(PPh3)2]I·2CH2Cl2 (3) with small amounts of platinum compounds as byproducts. The Pt(0) complex [(PPh3)2Pt(CH2CH2)] does not react with 1 but decomposes at elevated temperatures to give the known dinuclear complex [Pt2(PPh3)2(μ-PPh2)2] (4). The complexes 2 and 4 and the salt 3 could be characterized by X-ray analyses and the usual spectroscopic methods.