SYNTHESIS AND PHYSICOCHEMICAL STUDIES ON NEW IRON, COBALT, NICKEL ANDCOPPER-COMPLEXES OF SOME CARBOXYLIC-ACIDS

New metal complexes of carboxylic acids have been prepared by a new me thod based on the electrochemical oxidation of iron cobalt, nickel and /or copper in non-aqueous solution. The complexes were characterized b y analytical, conductivity, spectral and magnetic measurements. The Co (II) and Ni(II) complexes are suggested to have an octahedral structur e with partially covalent metal to ligand bonds. The 10 Dq, beta and B values agree with those reported for the proposed geometry. Cu(II) co mplexes possess a distorted octahedral structure. The proton-ligand fo rmation constant pK(a)(H), of isonicotinic acid and the stepwise stabi lity constants of its Fe3+, Co2+ and Cu2+ complexes have been determin ed potentiometrically in dioxane-water (1:1). The stabilities of the f ormed complexes were found to be in the order Fe3+ > Cu2+ > Co2+ which agrees well with Irving-Williams series.