Influence of tetrahedral distortion of CuN4 complexes on spectroscopic properties.: Synthesis, characterization and crystal structures of [Cu(N-(2-methylpyridyl)benzenesulfonylamidate)2], [Cu(N-(2-methylpyridyl) toluenesulfonylamidate)2] and [Cu(N-(2-methylpyridyl)naphthalenesulfonylamidate)2] compounds

A series of new N-sulfonamide ligands and their copper(II) complexes, [Cu(N-(2-methylpyridyl)toluenesulfonylamidate)(2)] (1), [Cu(N-(2-methylpyridyl)benzenesulfonylamidate)(2)] (2) and [Cu(N-(2-methylpyridyl)naphthalenesulfonylamidate)(2)] (3), have been synthesized and characterized. Single crystal X-ray analysis of the three-complexes revealed that all of them present a tetracoordinate CuN4 chromophore. The ligands act as bidentate, coordinating the metal ion through the pyridine and sulfonamido N atoms. The main structural difference among the compounds is the varied degree of distortion of square-planar stereochemistry. Complex 1 exhibits a regular square-planar geometry. In complexes 2 and 3 the tetrahedrality values of 50.2 degrees and 39.0 degrees respectively indicate a strong distortion. EHMO calculations on idealized models show the correlation between the geometrical distortion and the spectroscopic properties. (C) 2001 Elsevier Science B.V. All rights reserved.