Excited state evolution of the rhodium(iii) complex [Rh(iii)(phen)2(NH3)2]2+ (phen = 1,10-phenanthroline) has been investigated theoretically to gain a better understanding of light-driven activation of high-energy metal centered states. Ab initio molecular dynamics (AIMD) simulations show the significance of asymmetric motion on a multidimensional potential energy landscape around the metal center for activated crossover from triplet ligand centered (3LC) to triplet metal centered (3MC) states on picosecond timescales. Significant entropic differences arising from the structural distributions of the 3LC and 3MC states revealed by the simulations are found to favor the forward crossover process. Simulations at different temperatures provide further insight into the interplay between structural and electronic factors governing the 3LC → 3MC dynamics as a concerted two-electron energy transfer process, and the broader implications for photoinduced generation of high-energy 3MC states of interest for emerging photocatalytic applications are outlined.
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