Theoretical studies on aurophilicity and excited-state properties in binuclear gold (I) trithiocarbonate and related complexes

The MP2 and unrestricted MP2 methods were performed to fully optimize the structures of [Au2(S2CS)2]2− (1) in the ground and lowest-energy triplet excited states, respectively. It was shown that upon excitation the Au-Au distance shortens about 0.156 Å with respect to the 2.814 Å one in the ground state. In the calculations, vibrational frequencies at the MP2 level and solution absorption spectra at the TD-DFT level agree with experimental observations. The comparison among 1, [Au2(S2CC(CN)2)2]2− (2) and [Au2(S2CH2)2]2− (3) in ground- and excited-state properties was discussed in detail.