Mono- and polynuclear complexes from the reaction of palladium acetate with alpha-substituted thioethers and thiols

Palladium acetate reacts with α-substituted thioethers (RSCH(R′)Z; Z=ester, ketone, sulphone, substituted methyl) and the thiol HSCH2C(O)Me to give complexes whose composition and nuclearity depend mainly on the electronic properties of the sulphur ligand. If it contains sufficiently acidic hydrogen atoms, the acetato group is partially or totally removed as acetic acid to give complexes of the type [Pd3(μ-O2CMe)3(μ-RSCR′Z)3] and [Pd(SCH2C(O)Me)2]6. The stability of the trimers decreases with the steric hindrance of the substituents at the sulphur and at the methine carbon atoms. Stable mixed sphere complexes are obtained also with carboxylato ligands different from acetato as PhCOO− and MeSCH2COO−. When the substituted thioether has poor electronwithdrawing groups, its reaction with palladium acetate affords complexes of the type [Pd(η1-OAc)2(RSCH2Z)2], in which the sulphur donor atom has simply replaced one oxygen atom of the acetato ligand.