V. V. Kravchenko

Structural features of the crystalline iodide complexes of some rare-earth elements with carbamide and acetamide

New acetamide and carbamide complexes LnI3 · 4Ur · 4H2O (Ln = La, Eu, Dy, Ho, Y; Ur is carbamide) and LnI3 · 4AA · 4H2O (Ln = Nd, Eu, Dy, Ho, Y; AA is acetamide) are synthesized. The complexes are characterized by the data of chemical analysis, IR spectroscopy, and X-ray diffraction analysis. The ligands (water, carbamide, and acetamide molecules) are coordinated by the rare-earth element atoms through the oxygen atom, and the coordination polyhedron is a distorted square antiprism. The iodide ions are not coordinated and are located in the external sphere. The structural characteristics of the complexes are compared in the series [Ln(L)4(H2O)4]I3 (Ln = La, Nd, Eu, Gd, Dy, Ho, Er; L = AA, Ur).

Halide polyhydrates of some rare-earth elements: Synthesis and structures

Scandium, yttrium, lanthanum, cerium, and terbium bromides and iodides of the formulas [(H2O)5Sc(μ-OH)2Sc(H2O)5]Br4 · 2H2O (I), [(H2O)5Sc(μ-OH)2Sc(H2O)5]I4 (II), [Y(H2O)8]Br3 · 2H2O (III), [(H2O)7La(μ-Br)2La(H2O)7]Br4 (IV), [Ce(H2O)9]I3 (V), and [Tb(H2O)9]I3 (VI) were obtained and examined using X-ray diffraction and IR and Raman spectroscopy. It was found that the compositions and structures of complexes II and III differ from the literature data. Crystallographic parameters were obtained for isostructural complexes V and VI. It was demonstrated that the conditions of the synthesis and the possibility of protolysis are decisive for the formation of polynuclear oxo and hydroxo complexes of rare-earth metal halides.

Complexes of gadolinium and erbium iodides with carbamide: Synthesis and structures

The novel carbamide complexes of gadolinium and erbium iodides of the composition LnI34Ur·4H2O (Ln = Gd, Er; Ur = carbamide) were synthesized and studied by X-ray diffraction and IR spectroscopy. The ligands are coordinated to the central Gd or Er atom through the O atoms of water or carbamide molecules. The coordination polylhedron of Ln atoms is a distorted square antiprism. The iodide ions are not coordinated and lie in the outer sphere.

Complexes of erbium and lutetium bromides with carbamide: Synthesis and structures

The synthesis and data of the study of new complexes of erbium and lutetium bromides with carbamide, [Ln(Ur)4(H2O)4]Br3 (I and III) and [Ln(Ur)6(H2O)2]Br3 (II and IV) (Ln = Er and Lu), by IR spectroscopy and X-ray diffraction analysis are presented. For all four compounds, coordination with metal occurs through the oxygen atoms of the water and carbamide molecules. The coordination polyhedra of the Ln atoms are distorted square antiprisms. Coordination of four carbamide molecules does not change their planar structures. The bromide ions are not coordinated, existing in the external sphere. Many hydrogen bonds are observed in the structures of complexes of both types.

Polyiodide amide complexes of transition metals: Structures and raman spectra

The Raman spectra of the polyiodide complexes of d elements with urea (Ur) and acetamide (AA), namely, [M(Ur)6][I3]3 (M = Cr, Fe), Co(Ur)6][I3]2 · 2Ur, [Mn(Ur)6][I8], [Ni(AA)6][I3]2, [M(AA)6][I10 (M = Fe, Co, Cd), and [Co(AA)4(H2O)2][I12], are studied. The structure of [Cr(Ur)6][I3]3 is studied. The crystals of [Cr(Ur)6][I3]3 are monoclinic: space group C2/c, a = 15.260(5), b = 11.941(3), c = 20.506(6) Å, β = 106.14(3)°, Z = 4, V = 3589.4(18) Å3. The I-I bond length in the CdI2 · 4BA · 2I2 polyiodide complex amorphous to X-rays is estimated by a correlation between the I-I bond length and the frequency of vibrations of this bond in the Raman spectra.

Complexes of lanthanum, gadolinium, and erbium iodides with acetamide: Synthesis and structure

New acetamide complexes of lanthanum, gadolinium, and erbium iodides of the composition LnI3 · 4AA · 4H2 O (Ln = La, Gd, Er; AA = CH3CONH2) are synthesized and studied. The synthesized complexes are characterized by the data of chemical analysis and IR spectroscopy and are studied by X-ray diffraction analysis. The coordination of the ligands (water and acetamide molecules) by the lanthanum, gadolinium, or erbium atom occurs through the oxygen atoms. The coordination polyhedron of the Ln atom is a distorted square antiprism. The iodide ions are not coordinated and exist in the external sphere.

Acetylcarbamide complexes of some lanthanide bromides and chlorides: Syntheses and structures

Syntheses, IR spectroscopy, and X-ray diffraction analyses were carried out for acetylcarbamide (AcUr) and new complexes La(AcUr)2(H2O)5]Br3 (I), [Pr(AcUr)2(H2O)5]Br3 (II), [Nd(AcUr)2(H2O)5]Cl3 (III), and [Sm(AcUr)2(H2O)5]Cl3 (IV) (CIF files CCDC 992841 (AcUr), 992842 (I), 992844 (II), 992843 (III), and 992845 (IV)). The crystals of compounds I–IV contain complex cations [Ln(AcUr)2(H2O)5]3+ (coordination number of lanthanum is 9) and uncoordinated halide ions. The coordination polyhedron in the cases of compounds I and IV is a one-capped tetragonal antiprism, and it is a three-capped trigonal prism in the cases of compounds II and III. Molecules AcUr are coordinated to the Ln atoms via the bidentate mode through the oxygen atoms. They are transformed from the initial cis-trans conformation to the trans-trans conformation, which is due to the rotation of the -C(O)-NH2 fragment around the nitrogen atom of the imino group. The angles between the O(1)C(1)N(3) and O(2)C(4)N(3) planes in the coordinated AcUr molecules are different, which can be due to the electronic structure of the central atom and spatial characteristics of the complexes. The coordinated AcUr molecules are joined to the halide ions and water molecules of the adjacent complex cations by hydrogen bonds.

On the reaction products of lanthanide chlorides with biurete

The synthesis and results of IR spectroscopy and X-ray diffraction analysis of new complexes of biurete NH2CONHCONH2 (BU) with the composition LnCl3 · 2BU · 4H2O, where Ln = La (I), Pr (II), Ho (III), Er (IV), and Lu (V), are presented. Crystals of complexes I–V include complex cations [Ln(H2O)4(BU)2]3+ and uncoordinated chloride ions. The coordination mode of biurete molecules is bidentate through the oxygen atoms, and upon coordination the BU molecules are transformed from the initial trans to cis configuration. Water molecules are also coordinated through the oxygen atom (the shape of the polyhedron of the Ln atoms is a two-capped trigonal prism). The oxygen atoms of both BU molecules and the oxygen atoms of the first and second water molecules form a trigonal prism, whereas the oxygen atoms of the third and fourth water molecules form two caps of the coordination polyhedron. The coordinated BU molecules are joined with the chloride ions and water molecules of the adjacent complex cations by hydrogen bonds. The degree of conversion of trans-BU to cis-BU in the lanthanide series of complexes of this type is discussed.

On the complexes of yttrium chloride with carbamide and acetamide

Data on the synthesis and the IR spectroscopic and X-ray diffraction analyses of new complexes of yttrium chloride with carbamide (Ur), [Y(Ur)4(H2O)4]Cl3 (I) and [Y(Ur)6(H2O)2]Cl3 (II), and with acetamide (AA), [Y(AA)5(H2O)2]Cl3 (III), are presented. The coordination of the ligands occurs through the oxygen atoms. For complexes I and II, the coordination polyhedra of the Y atoms are distorted tetragonal antiprisms. For structure III, the coordination polyhedron of the Y atom is a distorted pentagonal bipyramid. The coordination of four Ur molecules in complex I does not change their planar structure, and two Ur molecules in structure II have the dihedral angle N-C(O)-N different from 180°. The chloride ions are in the external sphere. Many hydrogen bonds are observed in the structures of complexes I–III.

Synthesis, X-ray crystal structure, and properties of antipyrinium perchlorates, hexakis(antipyrine)thulium- and hexakis(antipyrine)ytterbium perchlorates. Quantum-chemical studies of ligands protonation

Protonation of the bioactive ligand-antipyrine (AP, 2,3-dimethyl-1-phenyl-3-pyrazolin-5-one) has been considered, the crystal packing specific features for the protonated antipyrine perchlorate compounds ([APH]ClO4 · H2O (1, 2) and [AP2H]ClO4 (3, 4)), as well as the crystal structure particularities for [Tm(AP)6](ClO4)3 (5) and [Yb(AP)6](ClO4)3 (6) have been elucidated. The protonation ability—complex formation ability relationship has been revealed for a number of organic ligands. Quantum-chemical calculations (DFT) and comparison with the experimental data allowed aligning some organic ligands in a row according to their ability to be protonated and to be incorporated into the inner coordination sphere of the complex.