Abstract
ABSTRACT. New hydrazine complexes of some divalent transition metal ions of formulae, [M{(2-ab)2(N2H4)}].3H2O, [M{(3-ab)2(N2H4)}].3H2O and [M{(4-ab)2(N2H4)2}].2H2O where M = Co, Ni, Zn and Cd; 2-abH = 2-acetoxy benzoic acid, 3-abH = 3-acetoxy benzoic acid and 4-abH = 4-acetoxy benzoic acid were prepared using their respective metal nitrates and hydrazine hydrate at pH 6 and 5, respectively, and characterized by elemental analysis, IR and UV-reflectance spectroscopic techniques, thermo analytical technique, powder XRD, SEM-EDX and magnetic susceptibility measurements. All the transition metal complexes were sparingly soluble in water. The IR spectra of complexes showed N-N absorptions of hydrazine in the range of 964-988 cm-1 substantiating the bidentate bridging coordination of hydrazine. They showed endothermic decomposition in the range of 67-100 °C, exothermic dehydrazination in the range, 210-281 °C and an oxidative decomposition between 350 and 490 °C to form their respective metal oxides. The electronic spectral and magnetic susceptibility data could substantiate the distorted octahedral geometry of nickel and cobalt complexes and the XRD pattern indicates the existence of isomorphism. Crystals of [Cd(H2O)3((C6H4(4-OH)(COO))2].H2O obtained as by-product, was also characterized using single crystal XRD, IR and thermal studies.
 
 KEY WORDS: Acetoxy benzoic acids, Hydrazine, Thermal analysis, Single crystal XRD
 
 Bull. Chem. Soc. Ethiop. 2021, 35(2), 337-350. 
 DOI: https://dx.doi.org/10.4314/bcse.v35i2.9
Highlights
The isomers of acetoxy benzoic acids are capable ligands for the formation of complexes owing to the presence of COOH and CH3COO- groups attached with benzene ring
Hydrazine complexes of the first transition metal ions with a variety of carboxylic acids have been reported in the literature
Finding the fact that there is no other report on these acids using hydrazine, an attempt was made to synthesize hydrazine complexes of transition metal carboxylates
Summary
The isomers of acetoxy benzoic acids (abH) are capable ligands for the formation of complexes owing to the presence of COOH and CH3COO- groups attached with benzene ring. Biological activities of transition metal complexes based on 2-abH have been studied by Rubner et al In this work, it was shown that there was increased inhibitory action against various tumour cells [4]. Cu(II) complexes of halogen substituted 2-abH have been prepared and their thermal behavior have been studied by Tarulli et al [5].
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