Photophysical properties and crystal structures of luminescent phenylethynylgold(I) complexes of alkyl and aryl isocyanides

Several phenylethynylgold(I) complexes were prepared by treating [{Au(CC–Ph)}∞] with 2,5-diisocyano-2,5-dimethylhexane (L1), (1,8-diisocyano-p-menthane (L2) and 2,6-dimethylphenyl isocyanide in dichloromethane. The intermolecular Au ⋯ Au separations established by X-ray crystal analyses are 3.329(4), 3.565(2) and 3.485(3)Å for the crystals of [(Au(CCPh)(CNC6H3Me2-2,6)], [{Au(CCPh)}2L1] and [{Au(CCPh)}2L2] respectively. These gold(I) complexes have long-lived and emissive 3(ππ*) excited states in fluid solutions at room temperature. The photoredox properties of [Au(CCPh)(CNC6H3Me2-2,6)] have been studied by Stern–Volmer quenching experiments, and its excited-state redox potential E°(Au+–Au0*) is –1.62(1) V vs. saturated sodium chloride calomel electrode.