Complex of lanthanides with 4-chloro-2-nitrobenzoic acid

摘要

The conditions of the formation of lanthanide 4-chloro-2-nitrobenzoates were studied and their quantitative composition and solubilities in water at 293 K were determined. They are dihydrates and their solubilities are of the order of 10_(-3) mol/dm_3. The IR and X-ray spectra for the complexes were recorded. All complexes are crystalline compounds. Their thermal decomposition was studied. It was found that on heating above 523 K the complexes decompose explosively. Therefore their thermal decomposition was carried out in the temperature range 273-523 K. Dihydrates lose crystallization water molecules in one step. From the results it appears that during dehydration process no transformation of nitro-group to nitritotakes place. Their magnetic moments were determined in the temperature range 4.4-300 K and the complexes were found to obey the Curie-Weiss law. The values of .Ueff calculated for the all compounds (except that for Eu) are close to those obtained for Ln (III) by Hund and van Vleck. The interpretation of the results suggests that there is no influence of the ligand field on 4f electrons of the lanthanide ions in these polycrystalline compounds; 4f electrons probably do not participate in the formation of the Ln-O bonds. All complexes show the paramagnetic properties but the clear magnetic arrangement regions were not observed for them. In the case of neodymium 4-chloro-2-nitrobenzoate the loss compliance caused by the spin-spin interactions was noticed.