Photophysical studies of neutral LAu(I)X complexes (L=RNC;CO, X=halide) suggest that complexes associating as anti-parallel chains with long Au···Au distances exhibit orange-red phosphorescence with huge Stokesx shift (~20,000 cm^-1) while those associating as crossed-dimers exhibit counterintuitive blue-green emissions with smaller Stokesx shifts (~15,000 cm^-1) despite having much shorter Au···Au distances. Predictive information about the supramolecular structure is obtainable by the luminescence behavior. This is exemplified by crystals of {(1,1,3,3-tetramethyl)butyl}NCAuCl, whose orange luminescence anticipated an extended-chain supramolecular structure, which was later verified crystallographically. Photolysis of LAu(I)Cl complexes leads to dispropoportionation to AuCl₃ and gold nanoparticles with size that depends on L and reactant concentration. The photoproduct quantum yield (F) is dependent upon the photo-reactant concentration in solution for both RNCAuX and Au(CO)Cl. For (p-tosyl)CH₂NCAuCl, metallic gold forms with F=0.0065 and 0.032 in 4.0×10^-5 and 4.0×10^-3 M dichloromethane solutions, respectively. Moreover, metallic gold forms with F=0.013 and 0.065 upon irradiation of 8.0×10^-5 and 8.0×10^-3 M dichloromethane solutions of Au(CO)Cl, respectively. Hence, *[LAuX]_n oligomeric species are more photoactive than monomers. Most importantly, the results demonstrate intuitive control of the photoreactivity via modulation of the p-acceptance ability of L, as both follow the same order, CO>(p-tosyl)CH₂NC>(alkyl)NC.