Structural and spectral studies of novel Co(III) complexes of N(4)-substituted thiosemicarbazones derived from pyridine-2-carbaldehyde

Seven bis(ligand) Co(III) complexes {[CoL21]NO3·H2O(1), [CoL21]Cl·2H2O(2),[CoL21]ClO4(3), [CoL22]NO3(4), [CoL22]Cl·2H2O(5), [CoL23]Br·2H2O(6), [CoL23]ClO4·H2O(7)} of three thiosemicarbazone ligands {pyridine-2-carbaldehyde-N(4)-p-methoxyphenyl thiosemicarbazone [HL1], pyridine-2-carbaldehyde-N(4)-2-phenylethyl thiosemicarbazone [HL2] and pyridine-2-carbaldehyde-N(4)-(methyl),N(4)-(phenyl) thiosemicarbazone [HL3]} were synthesized and physico-chemically characterized. All complexes are assigned octahedral geometries on the basis of spectral studies. The ligands deprotonate and coordinate by means of pyridine nitrogen, azomethine nitrogen, and thiolate sulfur atoms. The single crystal X-ray structures of HL3 and two nitrate compounds are discussed. The structural studies corroborate the spectral characterization.

Graphical abstractTwo N(4) monosubstituted thiosemicarbazone ligands, pyridine-2-carbaldehyde-N(4)-p-methoxyphenyl thiosemicarbazone [HL1] and pyridine-2-carbaldehyde-N(4)-2-phenylethyl thiosemicarbazone [HL2] and a new N(4) disubstituted thiosemicarbazone ligand pyridine-2-carbaldehyde N(4)-methyl N(4)-phenyl thiosemicarbazone (HL3) and seven of their Co(III) complexes were synthesized and characterized physico-chemically using elemental analyses, conductance measurements, electronic and IR spectroscopic methods. The complexes were given the formulae [CoL21]NO3·H2O(1), [CoL21]Cl·2H2O(2), [CoL21]ClO4(3), [CoL22]NO3(4), [CoL22]Cl·2H2O(5), [CoL23]Br·2H2O(6) and [CoL23]ClO4·H2O(7). All the complexes are assigned octahedral geometries. The single crystal X-ray structures of HL3, [CoL21]NO3·H2O(1) and [CoL22]NO3(4) are discussed.Figure optionsDownload full-size imageDownload as PowerPoint slide