Metal β-diketone complexes. Part V. The interaction of β-diketones with diene complexes of palladium(II) and platinum(II)

Abstract

The compounds (β-diketonyl-cyclo-ene)M(β-diketonate)[M = Pd^II or Pt^II; β-diketone = CH₃CO·CH·CO·CH₃, CH₃CO·CH·CO·C₆H₅ or C₆H₅·CO·CH·CO·C₆H₅: cyclo-ene = C₈H₁₂ or C₁₀H₁₂] have been prepared from the reaction of the appropriate thallous β-diketonate with dihalogeno(cyclic-diene) compounds of palladium(II) and platinum(II). Reaction of these compounds with halogeno-acids, HX, produces the halogen-bridged dimers (C₈H₁₂-β-diketonyl)₂M₂X₂ and (C₁₀H₁₂-β-diketonyl)₂M₂X₂(M = Pd^II or Pt^II: X = Cl, Br, or I). Treatment of these derivatives with potassium thiocyanate gives the analogous thiocyanato-derivatives. With both classes of compound i.r. and n.m.r. data indicate that nucleophilic attack by the [CH(COR)₂]^– anion has occurred at a co-ordinated double bond with the production of σ-metal–carbon bond to the ligand with retention of co-ordination of the remaining olefinic group. Several isomers are produced during these reactions and their structures are discussed in the terms of the n.m.r. data. Mass spectral studies of these compounds together with the compounds C₈H₁₂Pt(CH₃)₂ and C₈H₁₂PtCl₂, and several thallous β-diketonates have also been carried out. It would appear that these studies allow a differentiation between O-bonded and C-bonded β-diketone species.

Treatment of the (C₈H₁₂ acac)₂Pt₂X₂ compounds with triphenylphosphine or arsine yielded the compounds (C₈H₁₂ acac)PtXL. These compounds are monomeric in benzene and nonelectrolytes. The analogous palladium compounds gave only [Ph₃P(As)]₂PdX₂ from this reaction.