Intricate Spin‐Vibronic Dynamics and Excited‐State Intramolecular Thiol Proton Transfer in Dithiotropolone
ABSTRACT
We perform a computational investigation to unravel the mechanisms of intramolecular thiol proton transfer and triplet formation in dithiotropolone. The S 1 and S 2 states are dipole‐forbidden, whereas S 3 and S 4 are dipole‐allowed states in this molecule. Upon initiating the nuclear wavepacket on S 3 , this molecule exhibits simultaneous S 3 to S 2 /S 1 internal conversion and S 3 ‐T 4 intersystem crossing. Further simulations reveal that the molecule shows ultrafast internal conversion in the triplet manifold, similar to its singlet dynamics. Apart from these decay processes in the Franck‐Condon region, this molecule can display thiol proton transfer via multiple singlet states due to low barrier energies along the reaction coordinate. The S 1 ‐T 4 and S 3 ‐T 5 /T 6 crossings upon the S‐H coordinate's elongation illustrate that the molecule can also show the triplet formation outside the Franck‐Condon region.
