Iron(II) complexes with a linear pentadentate ligand H2L1 = bis(N,N′-2-methylimidazol-4-yl-methylideneaminopropyl)methylamine and a monodentate ligand X (X = N3−, NCS−, NCSe−)

Three iron(II) complexes with a linear symmetrical pentadentate ligand H2L1 and a monodentate ligand X (X = N3−, NCS−, NCSe−), [FeIIN3(H2L1)]BPh4 (1), [FeIINCS(H2L1)]BPh4 (2), and [FeIINCSe(H2L1)]BPh4 (3), were synthesized and characterized, where H2L1 denotes bis(N,N′-2-methylimidazol-4-yl-methylideneaminopropyl)methylamine. Compounds 1, 2 and 3 consist of a mononuclear complex-cation of [FeIIX(H2L1)]+ (X = N3−, NCS−, NCSe−) and a tetraphylborate (BPh4−) anion. Each complex-cation has an octahedral coordination geometry with N6 donor atoms of a linear pentadentate ligand of H2L1 and a nitrogen atom of N3−, NCS−, or NCSe−, in which the linear pentadentate ligand is folded to coordinate to FeII ion in a cis-form. One of two imidazole groups of a complex-cation is hydrogen bonded to N3−, NCS−, or NCSe− of the adjacent complex-cation to form a cyclic dimer structure for 1 and a zigzag-chain structure for 2 and 3. The temperature dependence of the magnetic data revealed that 1, 2 and 3 are high-spin (HS) complexes.