Single Crystal Structure Analysis of Three Novel Iron(II) Coordination Polymers with Bridging 1,3,5-Tris(1H-1,2,4-triazol-1-yl)methyl)benzene

Three novel iron(II) coordination polymers, [Fe(H2O)2(ttmb)2](ClO4)2·4H2O (1), [Fe(H2O)2(ttmb)2](BF4)2·4H2O (2), [Fe(ttmb)2(NCS)2] (3), were synthesized with the linker 1,3,5-tris(1H-1,2,4-triazol-1-yl)methyl)benzene (ttmb). The single-crystal structures show that all three compounds form a double chain structure with the adjacent iron atoms being bridged by two ttmb linkers. The iron(II) ions are octahedrally surrounded by four N4 donor atom from the 1,2,4-triazol-1-yl groups of four different ttmb linkers which form an equatorial plane and two trans-coordinated aqua ligands in 1 and 2 or isothiocyanato ligands in 3 in the axial positions. In view of the neutral bridging ttmb linker, there is a counter-anion in all structures; uncoordinated ClO4– and BF4–in 1 and 2 or coordinated NCS–in 3. Compounds 1 and 2 are isostructural. Interestingly, the ttmb linker only utilizes two of its three potentially coordinating triazole groups. All iron(II) coordination networks are colorless or have a light-yellow color, being indicative of the high-spin state.