Synthesis, Characterization, and Reactivity of a Versatile Dinuclear Palladium β-Diiminate Complex

The reaction of (Ph2nacnac)H (Ph2nacnac = [CH(C(CH3)NPh)2]−) with [PdCl2(C6H5CN)2] in the presence of a base (KOtBu) yields [Pd(Ph2nacnac)Cl]2 (1) as an air- and moisture-stable solid. The dimeric structure in 1 has been confirmed by X-ray crystallographic analysis. This complex has proven to be a useful starting material for the rich and novel Pd-nacnac chemistry. Thus, treatment of 1 with neutral monodentate ligands N-methyl-4,5-diphenylimidazole (L1), 4-tert-butylaniline (L2), and CO results in the scission of the chloride bridge and the formation of mononuclear Pd species [Pd(Ph2nacnac)Cl(L1)] (2), [Pd(Ph2nacnac)Cl(L2)] (3), and [Pd(Ph2nacnac)Cl(CO)] (4), respectively. The reaction of 1 with an oxidant PhI(OAc)2 produces a novel homobimetallic complex [{Pd(Ph2nacCl)}2(μ-OAc)2] (5) (Ph2nacCl = [ClC(C(CH3)NPh)2]−), resulting from the oxidation of coordinated nacnac ligand rather than the Pd(II) metal center. In the presence of 6 equiv of CuCl complex 1 reacts with 4 equiv of L1 to afford a novel heteromultinuclear complex {[Pd(Ph2nacnac)(L1)2]2(μ-Cu6Cl8)} (6).