A ferrocenyl-substituted 1,2,4-triazole ligand and its FeII, NiII and CuII 1D-chain complexes

Abstract

As part of a program aimed at making bifunctional iron(ii) spin-crossover (SCO) materials, particularly those having redox/electron transfer as the second function, we have made the new ferrocene-triazole ligand ATF ([(4H-1,2,4-triazol-4-yl)amino]methylferrocene), (1), and a series of M(ii) complexes of this ligand with emphasis on iron(ii). Polynuclear 1D-chain complexes [Fe(ATF)3](Br)2·0.5(H2O) (2), [Fe(ATF)3](ClO4)2·0.5(H2O) (3), [Ni(ATF)3](ClO4)2·0.5(H 2O) (4) and an analogous complex formed with a positively charged ATF ligand [Fe(ATF+)3](ClO4)5 (6) were formed as polycrystalline powders. Crystals of a mixed ATF/NCS-bridged copper(ii) polymer [Cu(ATF)2(NCS)](ClO4)·(Et 2O)0.5(MeCN) (5) were formed and structurally characterised. Magnetic and Mössbauer spectral measurements on 2, 3 and 6 indicated that SCO has not been achieved though the Mössbauer data show interesting temperature dependence for doublets of the two iron sites for complexes 2 and 3. Solid state cyclic voltammetric data on the iron(ii) complexes 3 and 4 showed well defined, reversible ATF-based electrochemistry, similar to those shown by ATF in solution. © 2013 The Royal Society of Chemistry.