Complexes of a new bidentate chelating pyridyl/sulfonamide ligand with copper(II), cobalt(II) and palladium(II): crystal structures and spectroscopic properties

Reaction of the bidentate ligand 2-(2-aminophenyl) pyridine with p-toluenesulfonyl chloride afforded the new bidentate ligand HL which contains potentially chelating pyridyl and (protonated) sulfonamide N-donor binding sites. The crystal structure of the ligand shows that the sulfonamide NH proton is involved in a hydrogen-bonding interaction with the pyridyl N atom, resulting in a near-coplanar arrangement of the pyridyl and phenyl rings. Reaction of HL with various metal(II) acetates (M = Cu, Co, Pd) affords the neutral complexes [ML2] in each case in which the sulfonamide is deprotonated. All of these have been crystallographically characterised; the Cu(II) and Pd(II) complexes are planar, whereas the Co(II) complexes is pseudo-tetrahedral with the two CoN2 planes at 85 degrees to one another. Appropriate spectroscopic and electrochemical studies on the complexes are described. (C) 1998 Elsevier Science S.A. All rights reserved.