The phthalhydroxamate ligand and its divalent transition metal complexes: Synthesis, characterization, and spectral and thermal studies

The potassium salt of phthalhydroxamic acid (PHA) (alternatively named o-ca rboxybenzohydroxamic acid) was synthesized and its coordination behaviour w ith Mn(II), Co(II), Ni(II), Zn(II) and Cd(II) was studied. The hydroxamate ligand reacts with the transition metal ions to form polymeric complexes. T he ligand is coordinated to the metal ions through the deprotonated O and c arbonyl O of the hydroxamate group, and the carboxylate group, behaving as a tetradentate ligand. KPHA and its solid metal complexes were characterize d by elemental analyses, electronic and IR spectroscopy, and magnetic momen t measurements. The thermal decomposition behaviour of the ligand and the m etal complexes was also studied. On the basis of the experimental data, str uctures of the complexes are proposed.