The ground- and excited-state structures were fully optimized for a series of neutral binuclear Au(I) thiolates, [Au-2(dpm)(SCH2S)] (1) (dpm=bis(diphosphino)methane), trans-[Au-2(PH2CH2S)(2)] (2), and trans-[Au-2(SHCH2S)(2)] (3), by using the MP2 and CIS methods, respectively. The calculated Au-I-Au-I distances of about 3.0 A in the ground state of the complexes are indicative of aurophilic attraction between the two Au(I) atoms, while in their excited states the separations are greatly shortened (about 2.7-2.9 A). The promotion of Au d electron or S p electron into the bonding s(sigma) and/or p(sigma) lowest unoccupied molecular orbital of Au-I-Au-I results in such reinforcement of aurophilicity in the excited state. In the CIS calculations of the three Au(I) thiolates, we obtained the lowest-energy phosphorescent emission in the solid state for each of the complexes. The 462 nm emission of 1 was assigned as Au-->S charge transfer (MLCT) transition. But for 3, the charge transfer localized on the Au centers, (3)A(u)(s(sigma))-->(1)A(u)(d(sigma)(*)) (metal-centered charge transfer, MCCT), plays a main role in the 413 nm emission. Both the MCCT and MLCT transitions are important in the 323 nm emission of 2. The results indicated that Au-I-Au-I aurophilicity clearly influences luminescent properties of these complexes. (C) 2003 American Institute of Physics.