Transition metal complexes of N-(2-benzamide)pyridine-2′-carboxamide, a potentially tridentate ligand containing one secondary and one primary amide group: Preparation and characterization in the solid state

Abstract

The synthesis of N-(2-benzamide)pyridine-2′-carboxamide (LH 2) is reported along with its employment as a ligand. The new complexes [MCl 2(LH 2) 2]·DMF (M = Co, Ni), [Cu 2Cl 4(LH 2) 2]·DMF, [CuCl 2(LH 2) 2], [Co(OH)(LH)] n·nH 2O, [M 2(OH) 2(H 2O) x(LH) 2](M = Ni, Cu; x = 4,2), [M(LH) 2]·×H 2O (M = Ni, Cu; x = 0, 1), [Ni(H 2O) 2(LH) 2]·H 2O, and H 2O, and [CuCl(LH)] n, where DMF = N,N-dimethylformamide, have been isolated. The complexes were characterized by elemental analyses, conductivity measurements, x-ray powder patterns, thermal methods, variable-temperature magnetic susceptibilities, and spectroscopic (IR and far-IR, ligand field, ESR) studies. A variety of stereochemistries is assigned for the complexes in the solid state. The neutral ligand acts as a bidentate chelating agent with ligated atoms being the ring nitrogen and the secondary amide oxygen; the LH − ion behaves as a bidentate chelating N ring, N secondary amide or as a tridentate N ring, N secondary amide, O primary amide ligand depending mainly on the reaction conditions.