A cyanide-bridged FeII–MoV-based coordination polymer showing spin crossover

Abstract

A new cyanide–bridged Fe II –Mo V -based coordination polymer was synthesized. Magnetic and spectroscopic studies indicate that the 2D network displays an incomplete spin crossover (SCO). • A new cyanide-bridged Fe II –Mo V -based coordination polymer was synthesized. It is the first 2D [MoV(CN)]3–-based SCO complex. • X-ray diffraction, magnetic and IR spectra study revealed that 1 exhibited an incomplete spin transition with ca. 62% of the HS Fe II species transformed into the LS Fe II state. • magneto-structural analyses demonstrated that introducing more electron-donative ligands will improve the ligand field strength and therefore the completeness of SCO. Polycyanometallates are widely used in the construction of functional molecular magnetic materials owing to their versatile bonding modes and redox activities. However, only a few octacyanometallate-based complexes showed spin crossover (SCO) properties. In this work, we incorporate the bridging ligand 4,4'-Bis-(1H-imidazol-1-yl-methyl)biphenyl (bimb) into a cyanide-bridged Fe II –Mo V assembly, affording a two-dimensional spin crossover complex of {[Mo V (CN) 8 ][Fe II (bimb) 2 ]·0.5Hbimb} n ∙2H 2 O (1). The complex crystallizes in the P 1 ¯ space group and forms a layered structure. The two-dimensional layer is composed of one-dimensional [Fe II –CN–Mo V ] zigzag chains connected by the bridging ligand of bimb. Magnetic susceptibility measurements revealed that 1 exhibited an incomplete spin transition with ca. 62% of the high-spin (HS) Fe II species transitioned to the low-spin (LS) Fe II state upon cooling from 300 to 100 K.