Carboxylic esters as ligands. I. Metal chelates of diethyl oxaloacetate

Abstract

The β-keto-ester diethyl oxaloacetate forms stable non-ionic chelates with transition metal ions. The preparation of the diethyl oxaloacetates of a number of bivalent metals is described (M = Cu, Ni, Cu, Zn, Mn, Mg). Infrared measurements show that the ligand is bidentate in these chelates. The ethoxycarbonyl absorption is considerably lowered, which indicates a direct interaction between the ethoxycarbonyl group and the metal ion and this absorption follows the generally accepted stability order. Hydrolytic and ester exchange reactions undergone by the copper(II) chelate suggest that coordination occurs via the α-ethoxycarbonyl rather than the β-ethoxycarbonyl group of the ligand.