Complexes of the selected transition metal ions with 4-methoxycinnamic acid: Physico-chemical properties

Abstract

In this study, 4-methoxycinnamates of Mn(II), Co(II), Ni(II), Cu(II), Cd(II), Nd(III) and Gd(III) were synthesised. From the infrared (IR) spectra analysis of complexes, sodium salt and according to the spectroscopic criteria the carboxylate groups seem to be bidentate chelating. The complexes of 4-methoxycinnamates lose the water molecules in one or two steps. The final products of their decomposition are oxides of the respective metals. The enthalpy values of dehydration process were determined. The FTIR spectra of the gas phase products indicate that the decomposition of the complexes is connected mainly with the release of molecules of water (H2O), carbon dioxide (CO2), carbon monoxide (CO), methane (CH4) and other hydrocarbons. The analysed compounds follow the Curie-Weiss law. The magnetic moment values experimentally determined change as follows: from 5.90 μB to 6.27 μB for Mn(II) complex, from 4.57 μB to 4.99 μB for Co(II) complex, from 3.68 μB to 3.30 μB for Ni(II) complex, from 1.87 μB to 1.96 μB for Cu(II) complex, from 3.06 μB to 3.51 μB for Nd(III) complex, and from 6.91 μB to 6.90 μB for Gd(III) complex. © Akademiai Kiado, Budapest, Hungary 2012.