The properties of some complexes and salts containing the malonate or the C-substituted malonate group
Methods have been devised for the preparation of some malonate and C-substituted malonate salts and complexes with various metal ions. The solid state ultraviolet, visible and infrared spectra have been measured and discussed with respect to the bonding of the compounds. Infrared spectra studies confirmed that all complexes involve bonding through the carboxyl oxygen. Infrared analysis of these complexes confirmed the presence of two bands between 1600--1500 cm-1 and 1400--1350 cm -1. This differs from the position of such bands in the free acids, which upon coordination causes these bands to be shifted to lower or higher frequencies. The formation of these complexes through the carboxyl oxygen atoms has been confirmed from the X-ray analysis. The visible electronic spectra of the transition metal complexes indicated the most probable stereochemical shapes of the metal ion. The magnetic properties of Cu(II), Ni(II), Co (II), Fe(III), Mn(III) and Cr(III) complexes of malonate, ethyl and benzylmalonate were studied over a wide range of temperatures. The magnetic susceptibilities of all the compounds were found to be normal. Hence the Curie-Weiss Law was obeyed. The Mossbauer spectra of iron(III)malonate, ethyl and benzylmalonate complexes exhibited a similar pattern characteristic of a high-spin octahedral structure. X-ray crystallographic data of Zn(II), Cd(II), Ca(II), Ba(II), Co(III) and Al(III)malonate and Zn(II) ethylmalonate complexes are reported. However, X-ray powder photographs of Zn(II) malonate confirmed it asisomorphous with Co(II) and Ni(II)malonate. The crystal structure of Al(III) malonato complexes were studied by the single-crystal method and the cell parameters were obtained. Finally, 1H n.m.r. and 13C n.m.r. of some malonic acids and the chelated malonate group and the exchange of [alpha]-protons with deuterium from the solvent D2O are reported.