Noninnocent ligands: heteroleptic nickel complexes with α-diimine and 1,2-diketone derivatives.

Reaction of the Ni-Ni-bonded compound [(NiIL˙-)2] (1, L = [(2,6-iPr2C6H3)NC(Me)]2) with various 1,2-diketones afforded a series of heteroleptic complexes: [LNi(PhC(O)-C(O)Ph)] (2), [LNi(PhC(O)-C(O)Me)] (3), [LNi(3,5-tBu2C6H2O2)] (4), and [(LNi){μ-η2,η2-(MeC(O)-C(O)Me)}(NiL)] (5). Furthermore, the complex [Na(Et2O)][LNi{PhC(O)-C(O)Ph}] (6) was obtained by the reduction of 2 with 1.0 equiv. of Na metal. These complexes, which contain three potential redox-active centers, nickel and both α-diimine and 1,2-diketone ligands, were characterized by X-ray crystallography, NMR, EPR, and UV-vis-NIR spectra, magnetic susceptibility measurements, and DFT computations to elucidate their electronic structures.