Transition metal complexes of oximes derived from natural aldehydes : Synthesis, spectroscopic characterization and antimicrobial activities

A series of complexes of Co(II), Zn(II), Cd(II) and Hg(II) have been synthesized by the reactions of the metal chlorides with the sodium salt of oximes of citral (L(1)H) and citronellal (L(2)H) in 1: 2 stoichiometry in anhydrous dichloromethane. The oximes have been derived by the condensation reaction of hydroxylamine hydrochloride and citral or citronella, in 1 : 1 molar ratio in ethanol. The plausible structure of these newly synthesized complexes has been proposed on the basis of elemental analysis, molar conductance and various-spectral (IR, UV-Vis, (1)H and (13)C{(1)H} NMR) studies and four coordinated geometries have been assigned to these complexes. FAB mass spectra of 1 and 3 revealed the monomeric nature of these complexes. The powder XRD studies confirm the crystalline nature of the complexes. Studies were conducted to assess-the growth inhibiting potential of the complexes and oximes against three bacterial strains, S. aureus, B. subtilis Gram +ve and E. coli Gram -ve bacteria and two fungal strains, F. moniliformae and M. phaseolina. All complexes and oximes possess strong inhibitory action against microorganism. The results of antibacterial activity show that the Gram +ve bacteria S. aureus and B. subtilis are more susceptible than the Gram -ve bacteria E. coli. The antimicrobial activities of the complexes are found to be more than those of free oximes.