Synthesis, characterization and reactivity of platinum-substituted ketenes [PtX{?Ø1-C(PPh3)CO}L2]BF4, (X=Me, Cl; L2=1,5-cyclooctadiene, 1,2-bis(diphenylphosphino)ethane, cis-1,2-bis(diphenylphosphino)ethene). Steric and electronic effects of the ancillary

Ketenylidenetriphenylphosphorane, Ph3PC=C=O, 1, has been used to synthesize platinum-substituted ketenes [PtMe{ƒØ1-C(PPh3)CO}L2]BF4, 2a, b (L2=1,5-cyclooctadiene, cod (a), 1,2-bis(diphenylphosphino)ethane, diphos (b)). Parent compound [PtCl{ƒØ1-C(PPh3)CO}L2]BF4, 3, with L2=cis-1,2-bis(diphenylphosphino)ethene, diphoe, was also synthesized, which is stable only at low temperature. The stability of 2 and 3 and the reactivity of the C=C=O moiety have been examined and discussed in terms of the electronic and steric characteristics of the ancillary ligands, also taking into account the reactivity of the ¡¥PtXL2¡¦ fragment with other carbonyl stabilized phosphorus ylides, Ph3PCHCOR (R=Me, Ph, OMe, OEt).