Carbon–carbon double-bond cleavage in the reactions of diphenylcyclopropenone with platinum(0) complexes; crystal and molecular structure of µ-2-oxo-1,3-diphenylpropanediylidene-bis[bis(t-butyl isocyanide)platinum]

Abstract

Reaction of [Pt₃(CNBu^t)₆] with diphenylcyclopropenone in toluene affords the yellow crystalline title complex [Pt₂{µ-(PhC)₂CO}(CNBu^t)₄], the structural identity of which has been established by a single-crystal X-ray diffraction study. The complex is monoclinic, space group P2₁/n, Z= 4, with unit-cell dimensions a= 11.283(8), b= 19.821(6), c= 17.534(7)Å, and β= 90.23(4)°. Using 4 494 independent reflections, the refinement has converged to R 0.070 (R′ 0.069). The molecule shows the unusual feature of ring opening at the carbon–carbon double bond of the cyclopropenone, the resulting C₃ fragment symmetrically bridging the two platinum atoms. Reaction between cyclo-octa-1,5-dienebis(methyl vinyl ketone)platinum and diphenylcyclopropenone at –50 °C yields an analogous complex [Pt₂{µ-(PhC)₂CO}(cod)₂](cod = cyclo-octa-1,5-diene). Protonation of this species gives the cation [Pt₂{µ-(PhC)₂C(OH)}(cod)₂]⁺, while treatment with CNBu^t or P(OMe)₃ leads to displacement of the cod ligands.