Synthesis and spectroscopic and electrochemical properties of binuclear complexes of Au(III) bridged by 6,7-dimethyl-2,3-di(2-pyridyl) quinoxaline

A method of synthesis of new diimine complexes of Au(III) with a four-dentate bridging ligand 6,7-dimethyl-2,3-di(2-pyridyl) quinoxaline (Ddpq), [Au2(μ-Ddpq)Cl4]Cl2 and [(AuN^N)2(μ-Ddpq)](NO3)6, where N^N is ethylenediamine, 2,2′-bipyridyl, or 1,10-phenanthroline, is described and the composition, structure, and properties of these complexes are studied. The coordination-induced chemical shifts in the 1H NMR spectra are determined, as well as the spectral-luminescent and electrochemical parameters of the complexes. The nature of the energetically lowest spin-allowed 1(π-d*)-and spin-forbidden 3(π-π*) states is established.