Studies on some acid divalent-metal nitrilotriacetate complexes.

IR and H-1-NMR studies on nitrilotriacetic acid (H(3)NTA) suggest that the acid exists in the zwitterion form, which allows the existence of intermolecular hydrogen bonding. A tetrahedral structure is established for eleven (1:1) anhydrous acid-metal (II) nitrilotriacetates complexes. The ten Dq values for the colored complexes were determined spectrophotometrically. The pK(a) values for the eleven acid metal complexes [M(HNTA)]bullet>(*) over bar * (OH2)(3)] were determined and compared with the corresponding pK(a) values of the [M(OH2)(n)](+2) ions and also with the log beta (1) values of the corresponding [M(NTA)](-) complexes. X-ray diffraction studies on the ligand and on eight of these complexes are described.