A Light-controlled, Solvent-induced Spin-State Switching in a 3D Hexagonal Heterobimetallic Network

A cyanide bridged {4d-3d} heterobimetallic assembly of MoV-FeII with formula {[MoV(CN)8][FeII(v-im)4]2·BF4}n 2DMF·H2O (1·2DMF·H2O) was achieved by the self-assembly of [Mo(CN)8]3− and iron(II) with monodentate nitrogen donor ligand v-im (v-im = 1-Vinylimidazol). The complex was fully characterized by single-crystal X-ray diffraction analyses, spectroscopic and (photo)magnetic studies. Single crystal X-ray analyses revealed that the complex exhibits a three-dimensional (3D) hexagonal network structure of molybdenum(V) and iron(II) centers bridged by the cyanide ligands. The partially desolvated form 1·2DMF exhibit thermo-induced spin crossover (SCO) between LS Fe(II) and HS Fe(II) center over a wide range of temperature and light-controlled spin-state switching phenomenon at low temperature under light irradiation with TLIESST = 70 K whereas the fully solvated complex 1·2DMF·H2O remains in the HS state. This complex represents the first 3D coordination complex consists of iron(II) and [MoV(CN)8]3− units exhibiting reversible and complete SCO phenomenon and photo-magnetic effect.