Organometallic Chemistry of Ph₃PCCO. Synthesis, Characterization, X-ray Structure Determination, and Density Functional Study of the First Stable Bis-<i>η</i>¹-ketenyl Complex, <i>trans</i>-[PtCl₂{<i>η</i>¹-C(PPh₃)CO}₂]

Mono- and bis-η1-ketenyl Pt(II) complexes have been synthesized by reacting Zeise's salt or the related dimeric compound, [{PtCl2(C2H4)}2], with the oxocumulenic ylide ketenylidenetriphenylphosphorane, Ph3PCCO, 1, in suitable ratios. In particular, the η1-ketenyl derivative, trans-[PtCl2(C2H4){η1-C(PPh3)CO}], 2, has been isolated and characterized. The reaction of 2 with one more equivalent of 1 displaces the coordinated ethylene giving the first stable bis-η1-ketenyl derivative, trans-[PtCl2{η1-C(PPh3)CO}2], 6. The X-ray crystal structure of 6 shows a trans centrosymmetric geometry around Pt, with the PCCO moiety and the metal lying in a plane that forms an angle of ∼65° with the Pt(II) coordination plane. Density functional calculations indicate that steric effects play a leading role in determining such an arrangement. Data on the reactivity of 2 and 6 are also reported

Reaction of Ketenylidenetriphenylphosphorane (Ph₃PCCO) with Platinum(II) and Palladium(II) Complexes. Synthesis, Characterization, and Molecular Structure of [Pt(η³-C₃H₅){η¹-C(PPh₃)(CO)}(PPh₃)]BF₄

Ketenylidenetriphenylphosphorane, Ph3P CCO, reacts with Pt(II) and Pd(II) η3-allyl complexes (allyl = C3H5, 2-MeC3H4) to give neutral or cationic mononuclear η1-ketenyl derivatives [M(η3-allyl){(η1-C(PPh3)(CO)}L]m+ (L = Cl, m = 0; L = PPh3, m = 1) that have been characterized by elemental analysis, IR, and multinuclear NMR. The X-ray molecular structure determination performed on a single crystal of the air-stable derivative [Pt(η3-C3H5){η1-C(PPh3)(CO)}(PPh3)]BF4 furnishes the first crystallographic evidence of an η1-ketenyl derivative in which the ketene moiety is also involved in an ylide grouping