SYNTHESIS OF NEUTRAL AND CATIONIC PENTAFLUOROPHENYLPALLADIUM(I) DERIVATIVES. INSERTION VERSUS COORDINATION OF ISOCYANIDES IN BINUCLEAR PALLADIUM(I) COMPLEXES

Article abstract of DOI:10.1016/S0022-328X(00)99212-X

Reaction between PdX(C6F5)(dpm)2 (dpm=bis(diphenylphosphino)methane; X=Cl, Br, I, CNO or C6F5) and Pd2(dba)3CHCl3 (dba=dibenzylideneacetone) gives, the pentafluorophenyl palladium(I) derivatives .Treatment of with an excess of the ligand L, and in the presence of NaBPh4 gives the cationic complexes BPh4 (L=PPh3, P(OPh)3, pyridine or tetrahydrothiophene (tht)).Reaction with isocyanides RNC leads to three different types of compounds: (a) products with the isocyanide groups inserted into the Pd-Pd bond <(μ-RNC)> (X=C6F5; R=p-tolyl; X=Cl, R=p-tolyl or Cy); (b) cationic complexes with terminal isocyanides <(RNC)Pd(μ-dpm)2Pd(C6F5)>X (X=Cl; R=t-Bu; X=BPh4, R=p-tolyl, Cy or t-Bu), and (c) complexes which contain both bridging and terminal isocyanides, <(μ-RNC)<(RNC)Pd(μ-dpm)2Pd(C6F5)>BPh4> (R=p-tolyl or cyclohexyl).Addition of NaBPh4 to solutions of complexes of type a (X=Cl) results in deinsertion of the isocyanide to give complexes of type b.IR spectroscopy reveals that <(μ-CyNC)> isomerizes in CH2Cl2 to give <(CyNC)Pd(μ-dpm)2Pd(C6F5)>Cl, which upon recrystallization regenerates the former complex, showing that in this case the insertion-deinsertion process is reversible.