Unusual Stabilization of Ferriheme in Three Different Spin States upon Stepwise Cyanide Coordination in a Single Molecular Framework

. Single-crystal X-ray diffraction of the latter and DFT calculations further substantiate the coordination motifs. These findings establish a unique molecular platform that enables spectroscopically resolvable spin-state diversity in ferriheme, thereby opening new avenues for spin-dependent reactivity and the design of functional materials.