Organometallic Pd(III) complexes have been implicated as intermediates in a number of catalytic and stoichiometric transformations. While a few dinuclear organometallic Pd(III) complexes have been characterized, no mononuclear organometallic Pd(III) complexes have been isolated to date. Reported herein is the synthesis and characterization of a series of Pd(III) complexes supported by the tetradentate ligand N,N′-di-tert-butyl-2,11-diaza[3.3](2,6) pyridinophane (N4). Chemical or electrochemical oxidation of the Pd(II) complexes (N4)PdII(R)(X) (R = Me, X = Cl: 1; R = Ph, X = Cl: 2; R = X = Me: 3) generates [(N4)PdIIIMeCl]+ (1+), [(N4)PdIIIPhCl]+ (2+), and [(N4)Pd IIIMe2]+ (3+). These stable Pd(III) complexes were isolated and characterized by X-ray diffraction, cyclic voltammetry, UV-vis, EPR, magnetic moment measurements, and DFT to confirm the presence of paramagnetic d7 Pd(III) centers. Moreover, these Pd(III) complexes undergo light-induced C-C bond formation to give the corresponding homocoupled products ethane or biphenyl. Particularly remarkable is the observation for the first time of ethane formation from monomethyl Pd complexes.
ASJC Scopus subject areas
- Colloid and Surface Chemistry