Excitation-Dependent Spin-State Relaxation Mediated by Jahn–Teller Motion in a Mn(III) Complex
- 1Chemistry, School of Natural and Environmental Sciences
- 2Newcastle University
Abstract
Photoexcited transition-metal complexes exhibit complex excited-state dynamics arising from the interplay of electronic relaxation, spin-state conversion, and nuclear motion. Here, we use quantum dynamics to investigate the ultrafast photodynamics of the Jahn–Teller active complex Mn(terpy)Cl3. The high-spin d4 electronic configuration of Mn(III) produces strong coupling between electronic structure and molecular geometry, making this system an ideal platform for exploring nonadiabatic relaxation and spin-state evolution. Our simulations reveal that photoexcitation initiates coupled electronic and nuclear dynamics involving multiple excited states and spin manifolds. Population transfer is mediated by vibrational motion associated with the Jahn–Teller switching coordinate, which promotes both nonadiabatic transitions and intersystem crossing. We identify the dominant relaxation pathways, determine the key vibrational modes mediating population transfer, and establish the associated timescales. Importantly, the relaxation dynamics depend strongly on the initially prepared electronic-state composition, with different excitation energies accessing distinct regions of the excited-state landscape and leading to different decay mechanisms. These results provide a mechanistic understanding of excited-state relaxation in a prototypical Mn(III) complex and demonstrate how selective photoexcitation can influence spin-state evolution, offering insights relevant to the optical control of molecular magnetism.
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BibTeX
@misc{penfold2026excitationdependent,
title = {{Excitation-Dependent Spin-State Relaxation Mediated by Jahn–Teller Motion in a Mn(III) Complex}},
author = {Thomas James Penfold and Julien Eng},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008389/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008389/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Excitation-Dependent Spin-State Relaxation Mediated by Jahn–Teller Motion in a Mn(III) Complex
AU - Thomas James Penfold
AU - Julien Eng
PY - 2026
DA - 2026/09/07
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008389/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008389/v1
AB - Photoexcited transition-metal complexes exhibit complex excited-state dynamics arising from the interplay of electronic relaxation, spin-state conversion, and nuclear motion. Here, we use quantum dynamics to investigate the ultrafast photodynamics of the Jahn–Teller active complex Mn(terpy)Cl3. The high-spin d4 electronic configuration of Mn(III) produces strong coupling between electronic structure and molecular geometry, making this system an ideal platform for exploring nonadiabatic relaxation and spin-state evolution. Our simulations reveal that photoexcitation initiates coupled electronic and nuclear dynamics involving multiple excited states and spin manifolds. Population transfer is mediated by vibrational motion associated with the Jahn–Teller switching coordinate, which promotes both nonadiabatic transitions and intersystem crossing. We identify the dominant relaxation pathways, determine the key vibrational modes mediating population transfer, and establish the associated timescales. Importantly, the relaxation dynamics depend strongly on the initially prepared electronic-state composition, with different excitation energies accessing distinct regions of the excited-state landscape and leading to different decay mechanisms. These results provide a mechanistic understanding of excited-state relaxation in a prototypical Mn(III) complex and demonstrate how selective photoexcitation can influence spin-state evolution, offering insights relevant to the optical control of molecular magnetism.
ER -