Organo-complexes of platinum derived from methyl vinyl ketone and bis(cyclo-octa-1,5-diene)platinum; X-ray crystal structure of (1,3-diacetylbutane-1,4-diyl)bis(triphenylphosphine)platinum

Abstract

Bis(cyclo-octa-1,5-diene)platinum reacts with methyl vinyl ketone at ca.–20 °C to give either [Pt{η²-CH₂:CHC(Me):O}₂(cod)](cod = cyclo-octa-1,5-diene) or [Pt{η²-CH₂:CHC(Me):O}₃]. The former complex readily isomerises to a platinacyclopentane [[graphic omitted]H[C(Me):O]}(cod)], from which the cod group may be replaced by CNBu^t or PPh₃ to give [[graphic omitted]H[C(Me):O]}L₂](L = CNBu^t or PPh₃). In order to establish the molecular structure of this class of complex a single-crystal X-ray diffraction study was made on the PPh₃ derivative crystals of which are triclinic, space group P, Z= 2, in a unit cell with lattice parameters a= 10.755(3), b= 18.172(3), c= 11.780(2)Å, α= 110.26(1), β= 114.89(2), and γ= 95.77(2)°. The structure has been refined to R 0.044 (R′ 0.041) for 8 596 independent reflections to 2θ⩽ 60°(Mo-K_αX-radiation) collected at room temperature. The platinacyclopentane ring has a head-to-tail arrangement for the CH₂·CH[C(Me):O] groups, is non-planar, and is disordered about the β-carbon atom carrying a C(Me):O group, revealing for this derivative the presence of two isomers. Reaction of [Pt{η²-CH₂:CHC(Me):O}₂(cod)] with oxygen, hexafluoroacetone. or (CF₃)₂C:C(CN)₂ affords five-membered platina-ring complexes [[graphic omitted]H₂}(cod)][X·Y = O·O, O·C(CF₃)₂, or C(CN)₂·C(CF₃)₂], while treatment with PPh₃, CNBu^t, or C₂F₄ gives [Pt{η²-CH₂:CHC(Me):O}L₂](L = PPh₃ or CNBu^t) and [[graphic omitted]F₂)(cod)], respectively. The latter dimerises in solution to yield [Pt₂(µ-CF₂·CF₂)₂(cod)₂].