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

Abstract

Seven bis(ligand) Co(III) complexes { [ CoL 2 1 ] NO 3 · H 2 O ( 1 ) , [ CoL 2 1 ] Cl · 2 H 2 O ( 2 ) , [ CoL 2 1 ] ClO 4 ( 3 ) , [ CoL 2 2 ] NO 3 ( 4 ) , [ CoL 2 2 ] Cl · 2 H 2 O ( 5 ) , [ CoL 2 3 ] Br · 2 H 2 O ( 6 ) , [ CoL 2 3 ] ClO 4 · H 2 O ( 7 ) } of three thiosemicarbazone ligands {pyridine-2-carbaldehyde-N(4)- p-methoxyphenyl thiosemicarbazone [HL 1], pyridine-2-carbaldehyde-N(4)-2-phenylethyl thiosemicarbazone [HL 2] and pyridine-2-carbaldehyde-N(4)-(methyl),N(4)-(phenyl) thiosemicarbazone [HL 3]} 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 HL 3 and two nitrate compounds are discussed. The structural studies corroborate the spectral characterization.