Copper(II) complexes with the N,N,O-tridentate ligand 6-amino-5-formyl-1,3-dimethyluracilato-(N6)-benzoylhydrazone: synthesis, spectral and XRD studies

From reactions between different Cu(II) salts and the Schiff base 6-amino-5 -formyl-1,3-dimethyluracil-benzoylhydrazone (H(2)BEZDO) in alcohol, six new copper complexes with simplified formulas [Cu(HBEZDO)(H2O)(MeOH)]NO3 (1), [CuCl(HBEZDO)(DMF)] (2), [CuBr(HBEZDO)]. 2H(2)O (3), CuBr(HBEZDO) (4), Cu(C lO4)(HBEZDO). H2O (5), and Cu(SO4)(1/2)(HBEZDO). 1 1/2H(2)O (6) were isolat ed. The structures of compounds 1, 2 and 3 have been established by means o f XRD diffraction methods. In the three compounds, the Schiff base acts as a tridentate monodeprotonated ligand through the N(6), N(51) and O(52) atom s, making two five- and six-membered chelate rings. In the structure of 1 a nd 2, the solvent molecules are coordinated giving square-based pyramidal e nvironments, with the basal plane completed by a MeOH (1) or Cl (2) and the apical positions occupied by the oxygen atom of a water (1) or a DMF molec ule (2). The molecular unit of the complex [CuBr(HBEZDO)]. 2H(2)O (3) is de fined by a square-plane containing the three donor atoms of the organic lig and and a bromide ligand (Cu-Br 2.384 Angstrom), but there is a stronger te tragonally elongated pyramidal geometry around the metal, the apical positi on of the polyhedron being occupied by a weakly bound-to-copper bromine ato m (3.086 Angstrom) of a neighbouring molecule. This fact gives the appearan ce of an apparent dimer with very asymmetric bromine bridges, in which ther e are no exchange interactions between metal centres. Also, infrared, magne tic and EPR data of the isolated complexes are reported. (C) 1999 Elsevier Science Ltd. All rights reserved.