Light-Induced, Structural Matrix Guided Stepwise Spin-State Switching in 3d-5d Molecular Assembly

A new iron(II) molecular complex {[W(CN)(8)][Fe(bik*)(3)](2)}BF4<middle dot>7H(2)O<middle dot>1.5CH(3)OH (1.7H(2)O<middle dot>1.5CH(3)OH) was synthesized using a versatile octacyanotungstate(V) building block and N-donor bidentate ligand (bik* = bis(1-ethyl-1H-imidazol-2-yl)ketone) and detailed characterizations were carried out. The crystal structure of 1.7H(2)O<middle dot>1.5CH(3)OH is composed of an ionic salt from one anionic [W(CN)(8)](3-) unit, two isolated cationic [Fe(bik*)(3)](2+) units, and one BF4- counteranion in the asymmetric unit. Magnetic studies of 1.7H(2)O<middle dot>1.5CH(3)OH display interesting two-step reversible thermo-induced spin-state switching and the partially desolvated form 1.7H(2)O shows a photomagnetic effect at low temperatures. Additionally, the physical properties of 1.7H(2)O<middle dot>1.5CH(3)OH were compared with the monomeric unit of {[Fe(bik*)(3)](2)}<middle dot>4ReO(4)<middle dot>H2O (2.H2O) and detailed photophysical investigations were also performed to study the effect of a structural matrix {[W(CN)(8)](3-) and ReO4- unit} on the spin-state switching properties of the [Fe(bik*)(3)](2+) unit in both systems (1.7H(2)O<middle dot>1.5CH(3)OH and 2.H2O).