Lanthanide(III) 4-nitrocinnamates were synthesized as polycrystalline hydrated solids with the general formulae: Ln(C9H6NO4)3OH2O (where Ln = lanthanons (without Ce(III)), n=1 for La, Pr-Tb and n=2 for Dy-Lu). The complexes were characterized by elemental analysis, FTIR spectroscopy, magnetic and thermogravimetric studies and also by X-ray diffraction (XRD) measurements. The carboxylate groups bind as bidentate chelating. On heating to 1173 K in air all compounds at first dehydrate in one stage to form anhydrous salts, that next with rising temperature are being directly decomposed (complexes of Pr(III) and Eu(III)) or with the intermediate formation of oxycarbonates (the rest of analysed compounds) to the oxides of respective metals. The gaseous products of compound thermal decomposition in nitrogen were also determined. The magnetic susceptibilities were measured over the ranges 76-303 K and 1.8-303 K, and their magnetic moments were calculated. The results show that 4-nitrocinnamates of lanthanides(III) are high-spin complexes with weak ligand field.

Complexes of Ni(II) 2,3-, 3,5- and 2,6-dimethoxybenzoates have been synthesized, their physico-chemical properties have been compared and the influence of the position of -OCH3 substituent on their properties investigated. The analysed compounds are crystalline, hydrated salts with green colour. The carboxylate ions show a bidentate chelating or bridging coordination modes. The thermal stabilities of Ni(II) dimethoxybenzoates were investigated in air in the range of 293-1173 K. The complexes decompose in three steps, yelding the NiO as the final product of decomposition. Their solubilities in water at 293 K are in the order of 10-2-10-4 mol<FONT FACE=Symbol>×</FONT>dm-3. The magnetic susceptibilities for the analysed dimethoxybenzoates of Ni(II) were measured over the range of 76-303 K and the magnetic moments were calculated. The results reveal that the complexes are the high-spin ones and the ligands form the weak electrostatic field in the octahedral coordination sphere of the central Ni(II) ion. The various position -OCH3 groups in benzene ring cause the different steric, mesomeric and inductive effects on the electron density in benzene ring.