Synthesis and spectral studies on metal complexes with the neutral O,N,O-tridentate Schiff base 6-amino-5-formyl-1,3-dimethyluracil-benzoylhydrazone - Crystal structure of a bidimensionally hydrogen-bonded perchlorate copper(II) complex

From the reaction between different Co(II), Cu(II), Zn(II) and Pd(II) salts and the Schiff base 6-amino-5-formyl-1,3-dimethyluracilbenzoylhydrazone (H (2)BEZDO), in ethanol and acetone media, five complexes with M/L stoichiome try 1/1, containing the neutral organic ligand, have been obtained. These c ompounds have been studied by IR, C-13 and H-1-NMR, UV-VIS-NIR and EPR spec troscopies and magnetic measurements. A single crystal X-ray diffraction st udy has been carried out on the compound [Cu(ClO4)(H(2)BEZDO)(H2O)]ClO4. Th e structure consists of mononuclear cations [Cu(ClO4)(H(2)BEZDO)(H2O)](+) a nd uncoordinated perchlorate anions, The coordination environment around th e Cu(II) may be described as a square-based pyramid in which the Schiff bas e acts as tridentate ligand through the O(4), N(51) and O(52) atoms, making two five- and six-membered chelate rings. The coordination sphere is compl eted with the oxygen atom of the water molecule and an oxygen atom of a wea kly coordinated perchlorate group occupying the apical position of the poly hedron. Both complex units and uncoordinated perchlorate anions are extensi vely hydrogen-bonded, forming bidimensional sheets. (C) 1999 Elsevier Scien ce Ltd. All rights reserved.