Octahedral Co(II) and Ni(II) complexes of Schiff bases, semicarbazone and thiosemicarbazone, synthesis, biological, spectral, and thermal studies

A new series of cobalt(II) and nickel(II) complexes, [M(ligand)(H2O)2(Y)] (M = Co(II) or Ni(II); Y = Cl−, Br− or NO3 −), containing the Schiff-base semicarbazone and thiosemicarbazone, HL1 and HL2, formed from 4-hydroxycoumarin-3-carbaldehyde have been synthesized. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, infrared, electronic spectra, magnetic susceptibility, and conductivity measurements. An octahedral geometry has been suggested for the complexes. The metal complexes were screened for their antifungal and antibacterial activities on different species of pathogenic fungi and bacteria and their biopotency has been discussed.