Metal Ion Complexes of Arom atic Am ino Acids. III. Diacids and Polynuclear Monacids

Abstract

This research has shown that the complexes of aromatic alpha amino dicarboxylic acids and of 2-amino-3-naphthoic acid are stable to about the same degree as those of the methyl substituted anthranilic acids. Infrared data show that of the thirty-three possible compounds, eighteen exist as coordination complexes; none of these has been previously reported. Stability series have been predicted, and in the case of 2-amino-3-naphthoic acid, the sequence was identical with that of methyl substituted anthranilic acids; in the case of 3-aminophthalic acid, the order was considerably different, and no valid sequence could be derived for 2-aminoterephthalic acid. As expected, the 2-amino-3-naphthoic acid acted as a bidentate ligand, whereas the two substituted phthalic acids behaved as tridentates, although the structures assigned were different. In each case, coordinated water was possible, but often the relative unavailability of the coordination positions and the presence of varying amounts of water in the lattice of these very insoluble complexes made determination difficult. In most cases, at least one molecule of water was present.