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Ultrafast Intersystem Crossing vs Internal Conversion in α-Diimine Transition Metal Complexes: Quantum Evidence.

Maria FumanalEtienne GindenspergerChantal Daniel
Published in: The journal of physical chemistry letters (2018)
Whereas third row transition metal carbonyl α-diimine complexes display luminescent properties and possess low-lying triplet metal-to-ligand charge transfer (MLCT) states efficiently accessible by a spin-vibronic mechanism, first row analogues hold low-lying metal-centered (MC) excited states that could quench these properties. Upon visible irradiation, different functions are potentially stimulated, namely, luminescence, electron transfer, or photoinduced CO release, the branching ratio of which is governed by the energetics, the character, and the early time dynamics of the photoactive excited states. Simulations of ultrafast nonadiabatic quantum dynamics, including spin-vibronic effects, of [M(imidazole)(CO)3(phenanthroline)]+ (M = Mn, Re) highlight the role of the metal atom. An ultrafast intersystem crossing process, driven by spin-orbit coupling, populates the low-lying triplet states of [Re(imidazole)(CO)3(phen)]+ within the first tens of fs. In contrast, efficient internal conversion between the two lowest 1MLCT states of [Mn(imidazole)(CO)3(phen)]+ is mediated within 50 fs by vibronic coupling with upper MC and MLCT states.
Keyphrases
  • transition metal
  • electron transfer
  • energy transfer
  • molecular dynamics
  • room temperature
  • quantum dots
  • density functional theory
  • magnetic resonance
  • ionic liquid
  • contrast enhanced
  • monte carlo
  • metal organic framework