Unusual formation and reactivity of a diplatinum mu-phenylethenylidene complex: Synthesis and structures of cis,cis-[(PPh(3))(C6F5)(2)Pt(mu-eta(1):eta(3)-CHPhCCO)Pt(PPh(3))(2)] and cis,cis-[(PPh(3))(2)Pt{mu-eta(2)(C,S):eta(1)(C)-C(SPh)(CH(2)Ph)}Pt(C6F5)(2)(CO)] dinuclear compounds

The mu-phenylethenylidene-bridged diplatinum complex [(OC)(C6F5)(2)Pt(mu-C=CHPh)Pt-(PPh(3))(2)], 1, synthesized from the reaction between the mononuclear alkynyl-hydride trans-[Pt(C=CPh)H(PPh(3))(2)] and cis-[Pt(C6F5)2(CO)(THF)] (THF = tetrahydrofuran), displays a remarkable reactivity associated with the mu-vinylidene ligand under mild conditions. The reaction of 1 with PPh(3) (molar ratio 1:1) produces an unprecedented reductive coupling of the CO ligand and the vinylidene bridging group to give the compound cis, cis-[(PPh(3))(C6F5)(2)-Pt(mu-eta(1):eta(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-[(PPh(3))(2)Pt{mu(2)(C,S):eta(1)(C)-C(SPh)(CH(2)Ph)}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.