Spectral studies of cobalt(II) complexes of 12-membered macrocyclic ligands having thiosemicarbazone moieties

Cobalt(II) complexes of general composition [Co(L)X-2] and [Co(L-1)X-2] where (X = NO3-, CH3COO-, Cl-, Br-, NCS-, (1/2)SO4-2); L = 5,11-diethyl-6,12-dimethyl-3,8-dithione-1,2,4,7,9,10-hexaaza cyclododeca-1,4,6,10-tetraene and L-1 = 5,11-diethyl-6,12-dimethyl-3,8-dione-1,2,4,7,9,10-hexaaza cyclododeca-1,4,6,10-tetraene with tetradentate 12-membered macrocyclic ligands have been synthesized and characterized by elemental analysis, magnetic susceptibility, IR, electronic and electon spin resonance spectral studies. The various physico-chemical techniques suggest a coordination number six (octahedral geometry) for chloro, nitrato, bromo and thiocyanato complexes, and five-coordinated trigonal bipyramildal geometry for sulphato complexes. All the complexes are of high spin type showing magnetic moment corresponding to three unpaired electrons. All the complexes were also screened against bacteria and pathogenic fungi in vitro. (C) 2007 Elsevier B.V. All rights reserved.