Investigation of the effects of thiol ligands on the cis → trans isomerization of a series of dinuclear gold(I) complexes revealed an additional interesting photochemical process for the trans-(Aup-NBT)₂dppee complex. [p-NBT = para-nitrobenzenethiol, dppee = diphenylphosphinoethylene]. A crystal structure for the cis-(Aup-NBT)₂dppee reveals a short intramolecular gold-gold distance (3.0037(3)Å) while the trans-(Aup-NBT)₂dppee crystal is a dimer with intermolecular gold-gold distance of (3.1201(4)Å). The solid state trans-(Aup-NBT)₂dppee luminesces orange under UV light. UV-visible studies suggest that the cis complex isomerizes to the trans which immediately undergoes further reaction. This photochemical process is characterized by the reduction of the lowest energy peak (385 nm) and the increase in absorption at 320 nm with an isosbestic point at ca. 345nm. We speculate on the role of gold-gold interactions in the process. Ab initio calculations are used to interpret the results.