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 mu(eff) = 6.2mu(B) at room temperature. Depending upon the counteranion and the crystal solvent, the hexacoordinate complexes of Fe(111) show a great variability of the magnetic behaviour: in addition to (6)A states also T-4 and T-2 were identified. The complexes of M(II) show (6)A states for Mn(II), T-4 for Fe(II), T-3 for Co(II), and T 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. (C) 2002 Elsevier Science B.V. All rights reserved.