SOLVENT EFFECT ON THE STRUCTURES OF Co (II) SCHIFF BASE COMPLEXES DERIVED FROM 4-AMINOANTIPYRINE AND 2-HYDROXYBENZALDEHYDE (L1H) AND 2, 4-DIHYDROXYBENZALDEHYDE (L2H)

The title complexes are formed from the reaction of Schiff bases L1H or L2H with cobalt thiocyanate or cobalt azide in different coordinated solvents to afford solid materials with different colours ranging from red, dark green, greenish red to olive green depends on the solvent and the type of cobalt salt used. From the UV-Vis and IR spectra, these complexes exhibit binuclear structure with a coordination number six around each cobalt atom.
The solvents, EtOH, THF, CH3CN and MeOH, which are coordinated to the cobalt atom in the axial position transto either isothiocyanate or azide ligands can be replaced easily by methanol to give red complexes. In fact all the complexes are soluble in methanol and only the dark green complexes are soluble in certain organic solvents such as acetone and acetonitrile, the rest are insoluble in most organic solvents. Theses cobalt (II) complexes under this study are to be considered as solvent dependent.