Mixed-valence {FeII2FeIII4} hexanuclear complexes with thermally induced Fe(III) spin-crossover behavior
Shuwen Jia1, Lingyue Fan1, Chunyang Zheng2
1Key Laboratory of Pesticide and Chemical Biology of Ministry of Education, Central China Normal University, 430079 Wuhan, P. R. China. dfli@mail.ccnu.edu.cn.
Abstract:
Cyano-bridged mixed-valence {Fe6} hexanuclear complexes {[Tp4-MeFeII(CN)3]2[FeIII(Tpa)]2[FeIII(OR)(Tpa)]2}·6ClO4·S (Tp4-Me = tri(4-methyl-pyrazol-1-yl)borate, Tpa = tris(2-pyridylmethyl)amine; R = -CH3, S = 8MeOH 1, R = -C2H5, S = 6EtOH 2) have been obtained by building the units of [Tp4-MeFe(CN)3]- and [Fe(Tpa)]2+ in methanol and ethanol, respectively. Complex 1 exhibited single-crystal-to-single-crystal (SCSC) transformation to give {[Tp4-MeFeII(CN)3]2[FeIII(Tpa)]2[FeIII(OH)(Tpa)]2}·6ClO4·8H2O (3) in water. Detailed analysis of the coordination environment of the FeIII centers on the square lattice and magnetic susceptibility measurements of all the complexes confirmed their Fe3+ spin-crossover (SCO) properties (T1/2 = 178 K, 1; 185 K, 2; 208 K, 3).
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