REACTION OF KETENYLIDENETRIPHENYLPHOSPHORANE (PH(3)P=C=C=O) WITH PLATINUM(II) AND PALLADIUM(II) COMPLEXES - SYNTHESIS, CHARACTERIZATION, AND MOLECULAR-STRUCTURE OF [PT(ETA(3)-C3H5)(ETA(1)-C(PPH(3))(CO))(PPH(3))]BF4

Ketenylidenetriphenylphosphorane, Ph(3)P=C=C=O, reacts with Pt(II) and Pd(II) eta(3)-allyl complexes (allyl = C3H5, 2-MeC(3)H(4)) to give ne utral or cationic mononuclear eta(1)-ketenyl derivatives [M(eta(3)-all yl){(eta(1)-C(PPH3)(CO)}](m+) (L = Cl, m = 0; L = PPh(3), m = 1) that have been characterized by elemental analysis, IR, and multinuclear NM R. The X-ray molecular structure determination performed on a single c rystal of the air-stable derivative Pt(eta(3)-C3H5){eta(1)-C(PPh(3))(C O)}(PPh(3))]-BF4 furnishes the first crystallographic evidence of an e ta(1)-ketenyl derivative in which the ketene moiety is also involved i n an ylide grouping.