Spin crossover in iron(II) tris(2-(2-pyridyl)benzimidazole) complex monitored by the variable temperature EXAFS

Standard EXAFS equipment has been utilized in conducting the variable temperature experiments using the [Fe(pybzim)3](ClO4)2·H2O sample, pybzim being a bidentate 2-(2-pyridyl)benzimidazole ligand. There is a jump in the metal–ligand (Fe–N) distance comparable with the step in the effective magnetic moment. The distance increases from 1.95 to 2.11 Å. In the transition region, the error bars are much broader than before and after this region. The transition temperature taken from the fittings is 132 K, which is about 9 K lower than that from magnetic susceptibility measurements.