Synthesis, characterization and thermal behavior of cobalt(II) 5-chloro-piridylamides complexes

Purple cobalt(II) complexes containing 5-chloro-2-aminepyridylacetamide (CPA), 5-chloro-2-aminepyridylpropionamide (CPP) and 5-chloro-2-aminepyridylbutyramide (CPB) ligands were prepared from ethanolic solutions. The general stoichiometry CoL2Cl2 (L=ligand) was determined from elemental analysis data. Infrared results show monodentate CPA and CPP ligands through the aromatic nitrogen atom, CPB is bidentate through the aromatic nitrogen atom and carboxyl group. Thermogravimetric curves under nitrogen showed in the final stage all complexes presented a mixture of cobalt(II) chloride and metallic cobalt as residue. The complexes containing CPA and CPP ligands decomposed in various stages with integral loss of ligand or partial loss of the chloride. Only two steps of decomposition are seen for CPB compound.