Connecting Binuclear Pd(III) and Mononuclear Pd(IV) Chemistry by Pd–Pd Bond Cleavage

Abstract

Oxidation of binuclear Pd­(II) complexes with PhICl₂ or PhI­(OAc)₂ has previously been shown to afford binuclear Pd­(III) complexes featuring a Pd–Pd bond. In contrast, oxidation of binuclear Pd­(II) complexes with electrophilic trifluoromethylating (“CF₃⁺”) reagents has been reported to afford mononuclear Pd­(IV) complexes. Herein, we report experimental and computational studies of the oxidation of a binuclear Pd­(II) complex with “CF₃⁺” reagents. These studies suggest that a mononuclear Pd­(IV) complex is generated by an oxidation–fragmentation sequence proceeding via fragmentation of an initially formed, formally binuclear Pd­(III), intermediate. The observation that binuclear Pd­(III) and mononuclear Pd­(IV) complexes are accessible in the same reactions offers an opportunity for understanding the role of nuclearity in both oxidation and subsequent C–X bond-forming reactions