Preparation and structure of 2-(2-benzimidazol-2-yl)pyridine N-oxide and its complexes

The condensation product of pyridinecarboxaldehyde N-oxide with o-phenylene diamine yields a ligand 2-(2-benzimidazolyl)-pyridine N-oxide (poxbim) whic h has been isolated in a free form. The bidentate ligand gave a series of c omplexes with Mn(II), Fe(II), Co(II), NI(II), Cu(II) and Zn(II) with 1:1, 1 :2, 1:3, 1:4 and 1:5 metal-to-ligand ratios. The 1:2 cobalt(II) adduct, [Co (poxbim)(2)(H2O)(2)](ClO4)(2), has been structurally characterised. Its tem perature-dependent magnetic susceptibility shows a behaviour that is charac teristic for the octahedral T-4(1g) term under the axial distortion due to symmetry lowering to D-4h. The structure of a 1:4 zinc(II) adduct shows tha t two ligands remain uncoordinated in [Zn(poxbim)(2)(H2O)(2)](ClO4)(2) (pox bim)(2). 2H(2)O. (C) 2000 Elsevier Science B.V. All rights reserved.