The complexes of lanthanides(III) with hemimellitic acid (1,2,3-benzenetricarboxylic acid, H3btc) of the formula Ln(btc)·nH2O, where Ln=lanthanide(III) ion and n=2−6 were prepared and characterized by elemental analysis, infrared spectra, X-ray diffraction patterns and thermal analysis.
The IR spectra of the complexes indicate coordination of lanthanides(III) through all carboxylate groups. The complexes of
La(III), Ce(III), Pr(III) and Er(III) are amorphous. On heating in air atmosphere all complexes lose water molecules and next
anhydrous compounds decompose to corresponding metal oxides.
Authors:Zofia Rzączyńska and Anna Danczowska-Burdon
among 2,4-pyridinedicarboxylates derivatives [ 5 ]. Also many deviations from planarity were remarked which form two-dimensional [ 6 ] or even three-dimensional [ 7 ] structures. The lanthanide (III) coordination takes place through carboxylate groups
from La to Lu and they have the general formula of Ln2(C8H5O4N)3·8H2O. On heating in air or inert gas atmosphere they lose all water molecules in the temperature range 50–200°C in one or two
steps. The anhydrous compounds are stable from 360 to 435°C and then decompose to oxides.
Authors:Z. Rzączyńska, M. Woźniak, W. Wołodkiewicz, A. Ostasz, and S. Pikus
The complexes of yttrium(III) and lanthanides(III) with 5-amino-1,3-benzenedicarboxylic acid form two isostructural series
of compounds and have the general formula Ln2(C8H5O4N)3�nH2O, where n = 13 for Y, La-Er and n=9 for Tm, Yb, Lu. They are insoluble in water and stable at room temperature. On heating in air or inert gas atmosphere they
lose all water molecules in several steps. The anhydrous compounds are stable to about 400�C and next decompose to oxides.
Authors:W. Brzyska, A. Tarnawska, A. Twardowska, and E Wiśniewska
Y(III) and lanthanide(III) mesaconates were prepared as crystalline solids with general formula Ln2(C5H4O4)3⋅nH2O, where n=7 for La−Pr, n=4 for Y,Nd−Ho, n=8 for Er−Lu. IR spectra of the prepared mesaconates suggest that carboxylate groups are bidentate bridging anf chelating.
During heating the hydrated complexes are dehydrated in one (Y, Nd−Lu) or two steps (La−Pr) and then decompose directly to
oxides (Y, Ce, Pr, Sm, Gd−Lu) or with intermediate formation Ln2O2CO3 (La, Nd, Eu).
Authors:W. Ferenc, A. Dziewulska-Kułaczkowska, J. Sarzyński, and B. Paszkowska
4-Chloro-2-methoxybenzoates of heavy lanthanides(III) and yttrium(III) were obtained as mono-, di-, tri-or tetrahydrates with
metal to ligand ratio of 1:3 and general formula Ln(C8H6ClO3)3·nH2O, where n=1 for Ln=Er, n=2 for Ln=Tb, Dy, Tm, Y, n=3 for Ln=Ho and n=4 for Yb and Lu. The complexes were characterized by elemental analysis, FTIR spectra, TG, DTA and DSC curves, X-ray diffraction
and magnetic measurements.
The carboxylate group appears to be a symmetrical bidentate chelating ligand. All complexes are polycrystalline compounds.
The values of enthalpy, ΔH, of the dehydration process for analysed complexes were also determined. The solubilities of heavy lanthanide(III) 4-chloro-2-methoxybenzoates
in water at 293 K are of the order of 10−4 mol dm−3. The magnetic moments were determined over the range of 76–303 K. The results indicate that there is no influence of the
ligand field of 4f electrons on lanthanide ions and the metal ligand bonding is mainly electrostatic in nature.
Authors:Wiesława Ferenc, B. Cristóvão, J. Sarzyński, and Maria Wojciechowska
4-Chloro-2-methoxybenzoates of light lanthanides(III) were obtained as mono-, di-or trihydrates with metal to ligand ratio
of 1:3 and general formula Ln(C8H6ClO3)3·nH2O, where n=1 for Ln=Ce, Pr, n=2 for Ln=Nd, Sm, Eu, Gd and n=3 for Ln=La. The complexes were characterized by elemental analysis, IR spectra, thermogravimetric studies, X-ray diffraction and
magnetic measurements. The carboxylate group appears to be a symmetrical bidentate, chelating ligand. All complexes seem polycrystalline
compounds. Their thermal stabilities were determined in air. When heated they dehydrate to form anhydrous salts which next
are decomposed to the oxides of the respective metals. The solubilities of light lanthanide(III) 4-chloro-2-methoxybenzoates
in water at 293 K are of the order of 10−5 mol dm−3. The magnetic moments were determined over the range of 77–300 K. They obey the Curie-Weiss law. The values of μeff calculated for all compounds are close to those obtained for Ln3+ by Hund and Van Vleck. The results indicate that there is no influence of the ligand field of 4f electrons on lanthanide ions and the metal ligand bonding is mainly electrostatic in nature.
Authors:Zofia Rzączyńska, Anna Danczowska-Burdon, and Justyna Sienkiewicz-Gromiuk
Pyridine-2,5-dicarboxylic acid, known as isocinchomeric acid is one of six isomers containing two carboxylic groups. Light
lanthanide (III) complexes with pyridine-2,5-dicarboxylic acid with general formula Ln2L3·nH2O, where n = 8, 9, were obtained. Their thermal and spectroscopic properties were studied. Sodium salt was obtained as Na2L·H2O. Hydrated complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) are stable to 313–333 K, whereas
Na2L·H2O is stable to about 333 K. Dehydration process for all compounds runs in one stage, next they decompose into appropriate
lanthanide oxalates, oxocarbonates carbonates and finally to metal oxides. Bands of νCOOH vibrations at 1736 and 1728 cm−1 disappear on complex spectra and νas and νs of COO− groups appear thus indicating that complexation process took place.
Complexes of lanthanides(III) (La-Lu) and Y(III) with 3,4,5-trihydroxybenzoic acid (gallic acid) were obtained and their thermal decomposition, IR spectra and solubility in water have been investigated. When heated, the complexes with a general formula Ln(C7H5O5)(C7H4O5)·nH2O (n=2 for La-Ho and Y: n=0 for Er-Lu) lose their crystallization water and decompose to the oxides Ln2O3, CeO2, Pr6O11, and Tb4O7, except of lanthanum and neodymium complexes, which additionally form stable oxocarbonates such as Ln2O2CO3. The complexes are sparingly soluble in water (0.3·10–5–8.3·10–4 mol dm–3).