Exceptional Excited-State Lifetime of an Iron(II)-N-Heterocyclic Carbene Complex Explained

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Earth-abundant transition-metal complexes are desirable for sensitizers in dye-sensitized solar cells or photocatalysts. Iron is an obvious choice, but the energy level structure of its typical polypyridyl complexes, featuring low-lying metal-centered states, has made such complexes useless as energy converters. Recently, we synthesized a novel iron-N-heterocyclic carbene complex exhibiting a remarkable 100-fold increase of the lifetime compared to previously known iron(II) complexes. Here, we rationalize the measured excited-state dynamics with DFT and TD-DFT calculations. The calculations show that the exceptionally long excited-state lifetime (similar to 9 ps) is achieved for this Fe complex through a significant destabilization of both triplet and quintet metal-centered scavenger states compared to other Feu complexes. In addition, a shallow (MLCT)-M-3 potential energy surface with a low-energy transition path from the (MLCT)-M-3 to (MC)-M-3 and facile crossing from the (MC)-M-3 state to the ground state are identified as key features for the excited-state deactivation.


Enheter & grupper

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Atom- och molekylfysik och optik
  • Kemi
Sidor (från-till)2066-2071
TidskriftThe Journal of Physical Chemistry Letters
Utgåva nummer12
StatusPublished - 2014
Peer review utfördJa