Influence of a thermochromic anion on the spin crossover of iron(II) trinuclear complexes probed by Mössbauer spectroscopy

Abstract

The insertion of thermochromic anions (1 and 2) into triazole based iron(II) trinuclear spin crossover complexes [FeII3(hyetrz)6(H2O)6](1 or 2) 4Cl2 paves the way to a large panel of multifunctional materials. In addition to a gradual thermo-induced spin conversion of the central metal ion on cooling below room temperature, an unexpected split of the Mössbauer signal of the external iron(II) ions as well as pronounced relaxation phenomenon for the central HS iron(II) ion was discovered. This phenomenon is suggested to be induced by the tautomeric equilibrium between enol and keto forms of the anion. © 2010 IOP Publishing Ltd.