Bis(isothiocyanato)iron(II) complexes with bithiazole ligands: Structure and magnetic studies

Two new mononuclear iron(II) complexes, [Fe(4bt)2(NCS)2] (1) and [Fe(dm4bt)2(NCS)2] (2), were prepared from the treatment of FeCl2·4H2O and KSCN salts with 4,4′-bithiazole (4bt) and 2,2′-dimethyl-4,4′-bithiazole (dm4bt), respectively and their structures and magnetisms were studied. Crystal structure determination revealed similar distorted octahedral [FeN6] moiety for both high spin iron(II) complexes. Fe–N distances are seen in 1 and 2 to be in the range of 2.085(8)–2.173(3) for Fe–NNCS and 2.178(3)–2.279(7) Å for Fe–Nbt which is consistent with the assigned iron spin and oxidation states. Temperature dependent χmT showed that the complexes are magnetically resembled and behave as S = 2 systems with some zero-field splitting. Complexes 1 and 2 were also studied in solution by means of 1H NMR and UV–Vis spectroscopy techniques.