Novel two-step Fe-Au type spin-crossover behavior in a Hofmann-type coordination complex {Fe(4-methylpyrimidine)2[Au(CN)2]2}

A Hofmann-type two-step spin-crossover (SCO) complex with pyrimidine derivative ligand, {Fe(4-methylpyrimidine)2[Au(CN)2]2}, was synthesized, this complex shows two-step SCO phenomenon with intermediate state. Symmetry breaking occurs in intermediate state. These results reveal three spin states within the complex for high-spin (HS), HS0.5LS0.5, and low-spin (LS).