Novel complexes of 2,6-bis(benzthiazol-2-yl)pyridine

New complexes of 2,6-bis(benzthiazol-2-yl)pyridine (L) with Mn(II), Fe(II), Co(II), Ni(II), and Fe(III) were prepared and characterised by spectroscopic methods. The X-ray structure analysis confirmed that the ligand crystallises either in the free form L, or as a protonated product HL·ClO4. In both crystalline forms, the ligand adopts SNS conformation. Two complexes [FeLCl3]·S with the crystal solvent S=CHCl3 and CH3NO2 show an altered way of the crystal packing. The conformation of the ligand is NNN in both cases. The {FeN3Cl3} chromophore adopts geometry of a distorted elongated octahedron and yields a high-spin complex with μeff=6.2μB at room temperature. Depending upon the counteranion and the crystal solvent, the hexacoordinate complexes of Fe(III) show a great variability of the magnetic behaviour: in addition to 6A states also 4T and 2T were identified. The complexes of M(II) show 6A states for Mn(II), 5T for Fe(II), 4T for Co(II), and 3T for tetrahedral Ni(II). The [FeL(phen)](ClO4)2·CHCl3 system shows features of the spin crossover from the low-spin to the intermediate-spin state.