Aminoethanoic acid (1.13 g, 0.015 M) was added drop-wise with stirring; the mixture was then heated for 2 h.
The infrared spectra analyses of ligands 4-hydroxy-3-nitro-2H-chromen-2-one, aminoethanoic acid, and pyrrolidine-2-carboxylic acid and their corresponding coordination compounds were carried out and the relevant peaks ([cm.sup.-1]) are given in Table 1.