V. T. Panyushkin

Structure and vibration spectra of neodymium biglycinate

Abstract The X-ray diffraction analysis of neodymium biglycinate was carried out and it was ascertained that there are nine atoms in the internal coordination sphere of the neodymium ion: three aqua oxygen atoms, five oxygen atoms of carboxyl group, and a chlorine atom. Having such coordination the tested compound should be considered a dimer that has the structure: {[Nd(HGl)2(H2O)3Cl]Cl2}2. Vibration (IR and Raman) spectra of the compound were measured in the range 4000–40 cm−1. Calculations of the frequencies and the forms of normal vibrations for some molecular models, which describe the real complex, were made on the group calculation technique basis.

MIXED-LIGAND COMPLEXES OF THREE VALENT LANTHANIDE IONS WITH ACETYLACETONE AND SOME ORGANIC UNSATURATED ACIDS

Abstract The complexation in ternary systems Ln-L-A (Ln—lanthanide ions Ln (III) ; L—acrylic, methacrylic, maleic acids ; A—acetylacetone) have been investigated by pH-potentiometric titration technique and by NMR spectra lineshape analysis on the base of quantum-mechanical formalism of spin density matrix. Stability constants, NMR spectra, paramagnetic shifts, relaxation times and lifetimes of mixed-ligand complexes were determined. General conformities of the complexation according to the lanthanide row were revealed. The dependences of complex compounds stability on the lanthanide ionic radius are explained by joint influence of electrostatic and steric effects.

Complexation of Cerium Group Lanthanides with L-Malic Acid under an Excess of Metal Ions

Complexation of cerium group lanthanide ions (Ce, Pr, Nd, Sm) with L-malic acid in aqueous solutions was studied by pH-metric titration at a malic acid : lanthanide concentration ratio of 1 : 2, in the pH range of 3.0 to 9.0, and at ionic strength of 0.1 mol/l (KCl). The composition and the stability constants of L-malate complexes and hydroxo complexes of lanthanides were determined.

Potentiometric study of reactions of rare-earth elements with 3-allylpentanedione in a water-dioxane medium

Reactions of the ions of La, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, and Lu with 3-allylpentanedione (HL) in a water-dioxane (50 vol%) medium were studied by pH-metric titration. Stability constants of LnL2+ and LnL2+ complexes and pH range where these compounds are mainly formed were determined. The dependence of the stability constants on the atomic number of an element has a characteristic break on the gadolinium ion and shows that the stability of the complexes increases as the size of Ln3+ ions decreases.

Effect of the condition of synthesis on the composition and structure of copper(II) complexes with benzimidazole

The composition and structure of copper(II) benzimidazole complexes obtained by the reaction of CuCl2 with benzimidazole (BIm) were determined. At pH 4.5–5.5, depending on the reactant ratio, dimeric compounds with the composition Cu(BIm)4Cl2 · 2H2O and Cu(BIm)2Cl2 · H2O are formed. They are converted to monomers at about 200°C. At pH > 8, irrespective of the reactant ratio, the polymer (Cu(OH)L)n is formed. The complexation of copper(II) with benzimidazole in water and aqueous dioxane was studied by potentiometry, and the stability constants of the complex compounds and their dependence on the solvent composition were determined.

Frequencies and Modes of Normal Vibrations of Neodymium Biglycinate

Results of X‐ray structural, IR, and Raman spectroscopic studies of neodymium biglycinate are presented. A fragment‐by‐fragment calculation of frequencies and modes of normal vibrations is performed, providing a full description of experimental vibrational spectra. It is demonstrated that the compound under investigation should be considered as a dimer of (NdCl3 · 2HGl · 3H2O)2 composition. A set of force constants of neodymium biglycinate that can be used for theoretical analysis of vibrational spectra of rare‐earth elements with α‐amino acids is presented.

Coordination compounds of europium(III), terbium(III), dysprosium(III), samarium(III), and gadolinium(III) with 2-acetylbenzoic acid

LnAcbenz3 · 3H2O complexes of Eu3+, Tb3+, Dy3+, Sm3+, and Gd3+ with 2-acetylbenzoic acid (HAcbenz) have been synthesized. The complexes have been studied by thermogravimetry and infrared and luminescence spectroscopy. According to IR spectroscopy data, the complexation of Acbenz− with lanthanide ions occurs due to the bidentate coordination of carboxyl groups. According to thermal analysis, the complexes are dehydrated at a temperature above 140°C, and their thermodestruction begins at a temperature above 250°C. From the luminescence spectra measured at 77 and 300 K, it has been established that the integral luminescence intensity of EuAcbenz3 · 3H2O and TbAcbenz3 ° 3H2O is, respectively, 10 and 19 times higher than for tris-benzoates of the same metals. TbAcbenz3 ° 3H2O, the most intensively luminescing complex, is recommended for use as a promising luminescent material.

Lanthanide complexes with 2,4-dimethoxybenzoic acid

In this connection, we carried out synthesis of the lanthanides complex compounds with 2,4-dimethoxybenzoic acid (HL) [LnL3(H2O)2]·6H2O, where Ln = Sm, Eu, Gd, Tb, Dy. The complex compounds were synthesized by the reaction of water–alcohol solution of the corresponding lanthanide chloride and the ligand ammonium salt in a 1:5 molar ratio at pH ≈ 6.5. The resulting precipitate was filtered off, washed with alcohol, water and dried in air.

An NMR study of comenic acid and its salts with Li + and Na + in aqueous solution and solid state

The forms and structure of comenic acid and its salts with Na+ and Li+ in solution and solid state are studied by multinuclear NMR spectroscopy. The formation of dimeric structures of comenic acid in the solid state is shown. It is found that disubstituted sodium and lithium salts have different structures.

Solvation microdynamics of the Gd(3+) ion in 4-methyl-N-butylpyridinium tetrafluoroborate as probed by 19F NMR and EPR

The solvation dynamics of the Gd(3+) ion in the ionic liquid 4-methyl-N-butylpyridinium tetrafluoroborate was studied by 19F NMR and EPR.