A convenient synthesis of binuclear methylpalladium(II) complexes

Abstract

The complexes [Pd₂Me₂(µ-Cl)₂(PR₃)₂](R₃= Et₃, Bu₃, Me₂Ph, MePh₂ or Ph₃) have been prepared by reaction of [Pd₂Cl₂(µ-Cl)₂(PR₃)₂] with tetramethyltin in benzene at room temperature. The complexes [Pd₂Me₂(µ-Cl)₂(PR₃)₂] react with pyrazoles in the presence of 2 mol equivalents of base to give the bis(pyrazolato)-bridged binuclear methylpalladium(II) complexes [Pd₂Me₂(µ-N–N)₂(PR₃)₂][N–NH = pyrazole (Hpz), 3,5-dimethylpyrazole (Hdmpz), 3,4,5-trimethylpyrazole (Htmpz); PR₃= PEt₃, PBu₃, PMe₂Ph, PMePh₂ or PPh₃]. The platinum analogues, [Pt₂Me₂(µ-N–N)₂(PMe₂Ph)₂], were obtained by a similar reaction. All the complexes were characterized by elemental analysis, IR and NMR (¹H, ¹³C, ³¹P) spectroscopy. Both chloro- and pyrazolate-bridged palladium(II) complexes adopt a trans configuration, whereas the platinum complexes exist as a mixture of cis and trans isomers.