Synthesis,characterization, and thermal analysis of ternary complexes of nitrilotriacetic acid and alanine or phenylalanine with some transition metals

Ternary complexes of Co(II), Ni(II), Cu(II), and Zn(II) with nitrilotriacetic acid as a primary ligand and alanine or phenylalanine as secondary ligand were prepared in slightly acidic medium. The structures of the complexes were elucidated using elemental, IR, molar conductance, magnetic moment, UV–Vis spectrophotometry, and thermal analyses. The ternary complexes were isolated in 1:1:1 (M:HNTA:alaH) ratios, and the molecular structures were found to be [M(HNTA)(alaH)(H₂O)₂]. Thermogravimetric analysis confirmed this structure and that the water present is coordinated to the central metal atom. UV–Vis spectra showed that the complexes have octahedral symmetry.