Reductive Elimination of C6F5–C6F5 from Pd(II) Complexes: Influence of α‑Dicationic Chelating Phosphines

We report the synthesis and characterization through NMR and X-ray techniques of a series of [Pd­(C6F5)2(P∧P′)] complexes constituted by diphosphine chelating ligands of different nature and evaluate the rates for the challenging reductive elimination of C6F5–C6F5. By virtue of their very weak donor properties, dicationic ancillary ligands effectively promote the desired transformation. Density functional theory (DFT) calculations were performed to rationalize these findings. The Pd(0)-complexes formed after the elimination step could not be isolated because the Pd(0) center has a tremendous tendency to insert into one of the P–C+ bonds of the α-cationic ligands rendering Pd­(II)-phosphinidene complexes. The same behavior was observed for Ni(0) species.