Abstract
The formyl group of glyoxylate is hydrated, and metal chelate formation between the carbonyl group and the hydrated formyl group was investigated hrough IR spectra, pH measurements, etc. The molar ratio of glyoxylic acid to metal was 1 to 1 in Cu(II), Ni(II), Co(II), and Mn(II) chelates. Marked drop in pH was found on reaction with Cu(II), Al(III), or Fe(III) ion (Table I); Stretching vibration of C-O in the hydrated formyl group near 1090 cm-1 was split by cbelation (Figs. 4 and 5, and Table II), and the deformating vibration of O-H near I300 cm-1 shifted to a higher wave numbef by chelation. Asymmetric stretching vibration of the carboxylate group is almost the same as 1604 cm-1 or lower in Cu, Ni, Co, and Mn chelates, Therefore, M-O bonding in glyoxylic acid chelates of Cu and other metals is recognized as ionic. M-O bonding of Fe and Al is, however, coordinative, because Vas(coo) of these chelates is shifted to a higher wave number.
