Spin-crossover in iron(II) complexes with tris(pyrazol-1-yl)methane and сluster anions [{W6X8}X6]2– (X = Cl, Br, I)

Abstract Iron(II) complexes with tris (pyrazol-1-yl)methane (HC(pz) 3 ) and cluster anions [{W 6 X 8 }X 6 ] 2– (X = Cl, Br, I) of the composition [Fe(HC(pz) 3 ) 2 ][{W 6 X 8 }X 6 ]⋅2H 2 O ( (1 – 3)⋅2H 2 O ) were synthesized. The compounds were characterized by element analysis, single-crystal and powder X-ray diffraction measurements, infrared, diffuse reflectance spectroscopy and static magnetic susceptibility. The temperature dependence μ eff ( T ) shows that the high-temperature spin-crossover ( SCO ) 1 A 1g ↔ 5 T 2g is observed in both hydrates (1 – 3)·2H 2 O and dehydrated compounds (1 – 3) . SCO is accompanied by thermochromism.