Theoretical modeling of enantiomerization mechanisms of tetrahedral bis-(β-diiminato) Ni(II) complexes

The mechanism for the low-energy barrier degenerate enantiomerization (enantiotopomerization) of bis-chelate tetrahedral six-membered ring bis-(β-dialdiminato) Ni(II) complexes has been studied by applying DFT B3LYP/6-311++G(d, p) method to a model system of bis-[methyl-3-(methylimino)-prop-1-enyl)-amino] Ni(II). The energy preferred reaction path involves a spin crossover step via the minimal energy crossing points (MECP) located at the intersection of the lowest singlet and triplet PESs. The calculated energy barrier (18.6 kcal mol−1) is in a good agreement with the available experimental data.