A Mixed-Valence {Fe13} Cluster Exhibiting Metal-to-Metal Charge-Transfer-Switched Spin Crossover

It is promising and challenging to manipulate the electronic structures and functions of materials utilizing both metal-to-metal charge transfer (MMCT) and spin-crossover (SCO) to tune the valence and spin states of metal ions. Herein, a metallocyanate building block is used to link with a Fe-II-triazole moiety and generates a mixed-valence complex {[(Tp(4-Me))Fe-III(CN)(3)](9)[Fe-4(II)(trz-ph)(6)]}.[Ph3PMe](2).[(Tp(4-Me))Fe-III(CN)(3)] (1; trz-ph=4-phenyl-4H-1,2,4-triazole). Moreover, MMCT occurs between Fe(III)and one of the Fe(II)sites after heat treatment, resulting in the generation of a new phase, {[(Tp(4-Me))Fe-II(CN)(3)][(Tp(4-Me))Fe-III(CN)(3)](8)[(FeFe3II)-Fe-III(trz-ph)(6)]}. [Ph3PMe](2).[(Tp(4-Me))Fe-III(CN)(3)] (1 a). Structural and magnetic studies reveal that MMCT can tune the two-step SCO behavior of1into one-step SCO behavior of1 a. Our work demonstrates that the integration of MMCT and SCO can provide a new alternative for manipulating functional spin-transition materials with accessible multi-electronic states.