Unusual Formation and Reactivity of a Diplatinum mu-phenylethenylidene Complex: Synthesis and Structures of cis,cis-[(PPh3)(C6F5)2Pt(mu-eta1-eta3-CHPhCCO)Pt(PPh3)2] and cis,cis-[(PPh3)2Pt{mu-eta2(C,S):eta1(CC(SPh)(CH2Ph)}Pt(C6F5)2(CO)] Dinuclear Compounds

The -phenylethenylidene-bridged diplatinum complex [(OC)(C6F5)2Pt(-C=CHPh)Pt-(PPh 3)2], 1, synthesized from the reaction between the mononuclear alkynyl-hydride trans-[Pt(CCPh)H(PPh3)2] and cis-[Pt(C6F5)2(CO)(THF)] (THF = tetrahydrofuran), displays a remarkable reactivity associated with the -vinylidene ligand under mild conditions. The reaction of 1 with PPh3 (molar ratio 1:1) produces an unprecedented reductive coupling of the CO ligand and the vinylidene bridging group to give the compound cis,cis-[(PPh3)(C6F5) 2-Pt(-1:3-CHPhCCO)Pt(PPh 3)2], 2, which contains an expanded, unsaturated benzylideneketene bridging ligand. On the other hand, treatment of 1 with PhSH generates the new diplatinum compound cis,cis-[(PPh3)2Pt{-2(C,S): 1(C)-C(SPh)(CH2Ph)}Pt(C6F5) 2(CO)], 3, formed by a formal addition of the PhSH to the carbon-carbon double bond of the vinylidene group in 1. The structures of 2 and 3 have been fully elucidated by X-ray diffraction studies