Synthesis, luminescence and electrochemical properties of luminescent dinuclear mixed-valence gold complexes with alkynyl bridges

A series of luminescent dinuclear mixed-valence gold alkynyl complexes, [((BuC)-Bu-t boolean AND N boolean AND CtBu) Au-III(C C)-Au-I (PPh3)], [(Rc boolean AND N boolean AND CR)Au-III(C CC C) AuI(PPh3)] (R = H, Bu-t), [(RC boolean AND N boolean AND CR) Au-III(C CC6H4CuC) AuI(PPh3)] (R = H, Bu-t), and [(RC boolean AND N boolean AND CR) Au-III(C CC6H4C C)Au-I(P(C6H4R'-p)(3))] (R = H; R' = OMe, Cl) as well as the precursor complexes, [Au-III(tBuC boolean AND N boolean AND CtBu)(CuCSiMe3)] and [Au-III((BuC)-Bu-t boolean AND N boolean AND CtBu)(C CH)], have been synthesized and their electrochemical properties have been investigated. The molecular structures of a number of dinuclear mixed-valence gold alkynyl complexes have been determined by X-ray crystallography. For complexes with a butadiynyl bridge, the emission was derived from an admixture of metal-perturbed triplet intraligand ((IL)-I-3) [pi-pi* (RC boolean AND N boolean AND CR)] and [pi-pi* (C C-C C)] states while for complexes with a 1,4-diethynylbenzene bridge, the emission was assigned as derived from the excited state of the 3IL [pi -> pi* (C CC6H4C C)] origin. Computational studies have also been performed for selected complexes to support the assignment of the spectroscopic origin and the nature of the photophysical properties.