The octahedral manganese(III) complex, [MnIII(taa)] (H3taa = tris(1-(2-azolyl)-2-azabuten-4-yl)amine), has long been known as a rare example of (3d)4 spin-crossover system, having a steep spin-crossover phase transition at Tc = 48 K between a high-spin 5Eg and a low-spin 3T2g states. Since the high-spin state is obviously subject to the Jahn-Teller effect, the electronic states are coupled with lo