Synthesis, characterization and reactivity of platinum-substituted ketenes [PtX{η1-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 ligands

Ketenylidenetriphenylphosphorane, Ph3PC=C=O, 1, has been used to synthesize platinum-substituted ketenes [PtMe}eta(1)C(PPh3)CO}L-2]BF4, 2a.. b (L-2 = 1.5-cyclooctadiene, cod (a), 1,2-bis(diphenylphosphino)ethane, diphos (b)). Parent compound [PtCl{eta(1)-C(PPh3)CO}L-2]BF4, 3, with L-2 = 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). (C) 2002 Elsevier Science B.V. All rights reserved.