Photoinduced Low-Spin → High-Spin Mechanism of an Octahedral Fe(II) Complex Revealed by Synergistic Spin-Vibronic Dynamics.

ABSTRACT: The Fe(II) low-spin (LS; ¹A_1g, t_2g⁶e_g⁰) → high-spin (HS; ⁵T_2g, t_2g⁴e_g²) light-induced excited spin state trapping (LIESST) mechanism solely involving metal-centered states is revealed by synergistic spin-vibronic dynamics simulations. For the octahedral [Fe(NCH)₆]²⁺ complex, we identify an initial ∼100 fs ¹T_1g → ³T_2g intersystem crossing, controlled by vibronic coupling to antisymmetric Fe-N stretching motion. Subsequently, population branching into ³T_1g, ⁵T_2g (HS), and ¹A_1g (LS) is observed on a subpicosecond time scale, with the dynamics dominated by coherent Fe-N breathing wavepackets. These findings are consistent with ultrafast experiments, methodologically establish a new state of the art, and will give a strong impetus for further intriguing dynamical studies on LS → HS photoswitching.

SUBMITTER: Papai M 

PROVIDER: S-EPMC8456406 | biostudies-literature |

REPOSITORIES: biostudies-literature