Chemistry of metallacyclobutanones. Part 4. The synthesis of 1,3-diphenyl-substituted oxodimethylenemethane complexes of platinum(II) and palladium(II)via the dianion [PhCHC(O)CHPh]2–, and the X-ray crystal structure of [Pt{η3-CHPhC(O)CHPh}(AsPh3)2]·2CH2Cl2

Abstract

Treatment of the complexes cis-[PtCl₂L₂] or trans-[PdCl₂L₂] with the organopotassium reagent K₂[PhCHC(O)CHPh] in tetrahydrofuran affords the η³-oxodimethylenemethane (puckered metallacyclobutan-3-one) complexes [M{η³-CHPhC(O)CHPh}L₂](M = Pt, L = AsPh₃ or PPh₃; L₂= cyclo-octa-1,5-diene (cod); M = Pd, L = PPh₃ or PEt₃). X-Ray data indicate that these complexes contain highly non-planar metal–oxodimethylenemethane systems with both phenyl substituents adopting equatorial positions. In the synthesis of [Pt{η³-CHPhC(O)CHPh}(PPh₃)₂] a small amount of a trans diphenyl-substituted isomer is formed, along with the principal cis diequatorial isomer. N.m.r. data for the oxodimethylenemethane complexes are reported.