The Properties and Infrared Absorption Spectra of Nitrilotriacetate Chelates

Abstract

Infrared absorption spectra have been observed in NTA and its metal chelates, in solid states as well as in solution. The results indicate that NTA does not exist as zwitter ions in the solid state, that it behaves as a quadridentate ligand for such divalent metals as copper, nickel, cobalt, zinc, cadmium and lead, but that it behaves as a terdentate ligand for the alkaline earth metals. It is also found that the wave number of the νC=O band of the coordinated carboxylate group in the NTA chelates tends to shift to a higher value with an increasing chelate stability constant.