Deciphering Photoluminescence Dynamics and Reactivity of the Luminescent Metal-Metal-Bonded Excited State of a Binuclear Gold(I) Phosphine Complex Containing Open Coordination Sites

KGaA, Weinheim. Luminescent metal complexes having open coordination sites hold promise in the design of sensory materials and photocatalysts. As a prototype example, [Au₂(dcpm)₂)]²⁺ (dcpm = bis(dicyclohexylphosphanyl) is known for its intriguing environmental sensitive photoluminescence. By integrating a range of complementary ultrafast time-resolved spectroscopy to interrogate the excited state dynamics, this study uncovers that the events occurring in extremely rapid timescales and which are modulated strongly by environmental conditions play a pivotal role in the luminescence behavior and photochemical outcomes. Formed independent of the phase and solvent property within 0.15 ps, the metal-metal bonded ³5dσ6pσ state is highly reactive possessing strong propensity toward increasing coordination number at Au^I center, and with 510 ps lifetime in dichloromethane is able to mediate light induced C-X bond cleavage.