CINOXACIN COMPLEXES WITH DIVALENT METAL-IONS - SPECTROSCOPIC CHARACTERIZATION - CRYSTAL-STRUCTURE OF A NEW DINUCLEAR CD(II) COMPLEX HAVING 2 CHELATE-BRIDGING CARBOXYLATE GROUPS - ANTIBACTERIAL STUDIES

Several cinoxacin (HCx) complexes with divalent metal ions have been p repared and characterized by spectroscopic techniques. The crystal str ucture of [Cd-2(Cx)(4)(H2O)(2)] . 10H(2)O has been determined by X-ray diffraction, The complex is triclinic, space group P (1) over bar wit h unit-cell dimensions: a = 10.412(2), b = 11.119(2), c = 13.143(6)Ang strom, alpha = 76.78(4)degrees, beta = 74.59(3)degrees, gamma = 77.12( 3)degrees, V= 1406.0(8) Angstrom(3). In this complex each cadmium atom is heptacoordinated; the metal environment is formed by two O-keto an d two O-carbox atoms from two different cinoxacinate monoanions, two c arboxylate oxygen atoms from a third cinoxacinate ligand and by one wa ter oxygen atom on the seventh position, Two of the cinoxacinate ions act as tridentate chelate and bridging ligands and the other one as a bidentate chelate ligand. In the bridging monoanions the carboxylate g roup is behaving as a chelate ligand, All the complexes were screened for their activity against several bacteria, showing activity similar to that of cinoxacin. Additionally, the number of bacteria killed afte r 3 h of incubation with cinoxacin, [Cu(Cx)(2)] . 2H(2)O and [Co(Cx)(3 )]Na . 10H(2)O complexes was determined against E. coli ATCC 25922; th e copper compound presents paradoxical effect which has been described and related to the mechanism of action of quinolones. (C) 1998 Publis hed by Elsevier Science Inc. All rights reserved.