A theoretical study of spin–orbit coupling in an Fe(II) spin-crossover complex. Mechanism of the LIESST effect

Spin–orbit coupling (SOC) in an Fe(II) spin-crossover system, [Fe(2-pic)3]Cl2·EtOH, where 2-pic denotes 2-picolylamine, is studied to understand the mechanism of light-induced excited spin state trapping (LIESST). The effects of SOC between the 1T1(1T2, 5E) states and the 3T2 state are larger than those between the 1T1(1T2, 5E) states and the 3T1 state. This suggests that the 3T2 state can play a significant role in the LIESST and reverse-LIESST effects.