Effect of second-order spin-orbit coupling on the interaction between spin states in spin crossover systems

摘要: The second-order spin-orbit coupling is evaluated in two transition-metal complexes to establish the effect on deactivation mechanism of excited low-spin state systems that undergo spin transitions under influence light. We compare standard perturbational approach calculate interaction with a variational strategy based effective Hamiltonian theory and show former one can only be applied some special cases even then gives results largely overestimate interaction. combined geometry distortions leads sizeable interactions for states are nearly uncoupled symmetric (average) structure complex. This opens possibility direct from singlet triplet metal-to-ligand charge-transfer manifold final high-spin as suggested interpretation experimental data but so far not supported by theoretical descriptions light-induced crossover.