Synthesis, characterization and electronic spectra of cefadroxil complexes of d-block elements

Cefadroxil (CD) is an essential pharmaceutical drug used in curing many diseases. Due to its popular use in many pharmaceutical forms, attention is paid in this research to the synthesis and stereochemistry of new iron, cobalt, nickel, copper, and zinc complexes of this drug both in solution and the solid states. The spectra of these complexes in solution and the study of their stoichiometry refer to the formation of 1: 1 and 1:2 ratios of metal (M) to ligand (L). The calculated stability constants (K-f) of these complexes (1.5 x 10(7) to 5 x 10(13)) and the change in free energy of formation (DeltaG(f) = 2.5-12.5 kcal mol(-1) degree(-1)) are indicative of their high stability. The stereo chemical structure of the solid complexes was studied on the basis of their analytical, spectroscopic, magnetic, and thermal data. Infrared spectra proved the presence of M-N and M-O bonds. Magnetic susceptibility and solid reflectance spectral measurements were used to infer the structure. The prepared complexes were found to have the general formulae [ML(OH)(x)(H2O)(y)](H2O)(z)-M: Fe(II), x = 0, y = 2, z = 1; M: Fe(III) and Co(III), x = 1, y = 2, z = 1; M: Co(II) and Zn(II), x = 0, y = 1, z = 0; M: Ni(II) and Cu(II), x = 1, y = 0, z = 1; L: CD. Octahedral and tetrahedral structures were proposed for these complexes depending upon the magnetic and reflectance data and were confirmed by detailed mass and thermal analyses comparative studies. (C) 2003 Elsevier B.V. All rights reserved.