Journal Article

Spectrophotometric Determination and Corrosion Inhibitory of Co (II), Ni (II), Cu (II), and Zn (II) Complexes Derived from Nicotinic Acid Hydrazide

Abstract

Metal complexes formed by the reactions of Nicotinic acid Hydrazide (NAH) with copper (II), Cobalt (II), Nickel (II), and Zinc (II) sulphate ions were prepared and characterized by their infrared, electronic, magnetic moment, elemental analysis, solubility, molar conductivity, and melting point as well as their corrosion inhibition properties using the Weight Loss Method (WLM). The infrared spectra analysis showed the participation of the carbonyl group or the aromatic ring in the coordination of the metal and the ligands due to the presence of ?(N-H), ?(O-H), ?(C=N), ?(N-N), ?(C=N), ?(M-N) and ?(M-O) bonds; the electronic spectra data shows that the ligands and the metal complexes absorbed in the visible region due to charge transfer processes from the energy in the visible light due to the presence of σ-σ*, π-π* , and n-π* transitions and hence, provide evidence that they are all coloured compounds (Harvey, 2000); the magnetic moment shows that all the metal complexes where paramagnetic except the zinc hydrazide metal complex which is diamagnetic; the elemental analysis showed that the metal to ligand ratio of the complexes is 1:2 , the solubility data showed that the metal complexes where insoluble in distilled water, methanol, acetone, chloroform, ethyl acetate and dimethyl sulfoxide but were soluble in ethanol which indicates that the metal complexes are polymeric in nature; the molar conductivity analysis showed that the metal complexes exhibited weak ionic character which indicates that the ligands are part of the coordinate structure of the complexes; the melting point of the metal complexes increased from cobalt to nickel to copper to zinc metal complex thus, the zinc metal complex had the lowest melting point; the corrosion inhibition analysis using Weight Loss Method (WLM) showed that the nickel metal complex had the highest inhibition ability, followed by the zinc metal complex, then the copper metal complex and finally, the cobalt metal complex which indicates that the strength of adsorption of the metal complexes depended on the charge on the anchoring group rather than the heteroatoms

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