A ferrocenyl-substituted 1,2,4-triazole ligand and its Fe(II), Ni(II) and Cu(II) 1D-chain complexes.

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(H2O) (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)·(Et2O)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.

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