The excited state energy landscapes of the gold phosphine thiolate complexes (TPA)AuSCH(CH3)2 (TPA=1,3,5-triaza-7-phosphaadamantanetriylphosphine) and AuP(CH3)3SCH3 are investigated using time-dependent density functional theory (TDDFT). The potential energy surfaces generated for these systems show a large number of excited state crossings. Both complexes display a strong absorption to the S2 state, which corresponds to a ligand-to-metal transition. The S1 and T1 states are strongly spin-orbit coupled at the linear ground state geometry, which suggests that intersystem crossing is possible. Upon relaxation to the S1 and T1 states, the P-Au-S angle decreases and these states become separated in energy. The bulkier ligands of (TPA)AuSCH(CH3)2 prevent the structural stabilization of these excited states and any of them may be responsible for the emission observed at 1.86 eV when spin-orbit coupling is considered. The emission of the (TPA)AuSCH(CH3)2 system at 1.86 eV can also possibly be attributed to aggregation. Aggregation is favorable even at the ground state geometry due to the aurophilic interaction. In the excited state, a bonding interaction occurs between the gold atoms. For the [(TPA)AuSCH(CH3)2]2 dimer, both the T2 and S2 states may be at the origin of the observed emission.

Time-dependent density functional theory study of the excited state energy landscape of gold phosphine thiolate complexes

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.