O. V. Kovalchukova

Crystal structure of chlorido­{1-(2,3-dimethyl-5-oxido-1-phenyl-1H-pyrazol-2-ium-4-yl-κO)-2-[3-methyl-5-oxo-1-phenyl-4,5-di­hydro-1H-pyrazol-4-yl­idene-κO]hydrazin-1-ido-κN1}copper(II) from laboratory X-ray powder data

In the title copper(II) complex containing chloride and a derivative of 3-methyl-1-phenyl-4-hydrazopyrazolin-5-one, acting as a tridentate ligand, the CuII atom is in a slightly distorted square-planar coordination. Molecules stack in columns along the c axis.

Electron density, electrostatic potential, and spatial organization of ammonium hydrooxalate oxalic acid dihydrate heteromolecular crystal from data of diffraction experiment at 15 K using synchrotron radiation and theoretical calculations

A high-precision diffraction study at 15 K using synchrotron radiation and theoretical calculation of a heteromolecular crystal ammonium hydrooxalate oxalic acid dihydrate NH4+·C2HO4−·C2H2O4·2H2O (1) were carried out. The calculation was performed with the Kohn-Sham method taking into account periodic boundary conditions. The joint experimental and theoretical study allowed one to locate positions of hydrogen atoms and to reliably establish peculiar features of the electron density and electrostatic potential distributions in 1. Interatomic and molecular interactions were characterized based on the electron density properties within the framework of a quantum topological theory. The bond order indices were calculated from the experimental electron density without using the orbital notions. A new approach based on visualization of the ellipsoids whose semiaxes depend on the principal values of the electron density curvature at the bond critical points was used. It was found that charge transfer between ammonium cation and hydrooxalate anion in 1 dominates other electrostatic interactions in the crystal. Based on analysis of peculiar features of the electron density and electrostatic potential distributions in the crystal of 1, it was found that spatial organization of the crystal in hand is also governed by one more, weaker, electrostatic factor that originated from the presence of well-localized regions behind protons on the extensions of the lines of covalent bonds at the periphery of the molecules. In those regions, the electrostatic potential is higher than in other directions due to anisotropy of the electron density distribution. This feature mainly ensures directed complementary electrostatic interaction between corresponding fragments with negatively charged regions of neighboring molecules, such as the lone electron pairs and p-electrons.

Synthesis, structure, geometrical, and spectral characteristics of the (HLn)2[CuCl4] complexes. Crystal and molecular structure of bis(2-methylimidazolium) tetrachlorocuprate(II)

The (HLn)2[CuCl4] complexes (where Ln are organic nitrogen-containing bases with n = 1–6) were synthesized. The crystal and molecular structures of bis(2-methylimidazolium) tetrachlorocuprate(II), (HL1)2[CuCl4], were determined. The spectral characteristics of the complexes were measured. The correlations between the degree of distortion of the crystal structure of the tetrachlorocuprate anion and the hydrogen bond parameters and the spectral characteristics of compounds were obtained.

Complexes of 2,3-Dihydroxypyridine with Bivalent Metals. Crystal Structure of 2,3-Dihydroxypyridine

Crystal structure of 2,3-dihydroxypyridine (H2L) is determined. Mn(HL)Cl · H2O, Co(HL)Cl · 2H2O, Cu(HL)Cl, Ni(HL)OH · H2O, and Zn(HL)OH · H2O complexes are synthesized by reacting Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) chlorides with H2L in ethanol solutions and identified. In these complexes, 2,3-dihydroxypyridine is involved in coordination as a monoanion. Spectral parameters of neutral and anionic forms of a ligand are determined and the acidity and complex formation constants are calculated. The compositions of complexes are established.

Synthesis, spectral and crystallographic studies of coordination compounds of some d and f metals with N-nitrozo-N-(methyl)ethylhydroxylamine

Eleven complexes of some d and f metals with N-nitrozo-N-methylhydroxylamine (NMHA) and N-nitrozo-N-ethylhydroxylamine (NEHA) were synthesized, separated out in a crystalline state, and characterized by a set of physicochemical methods (elemental analysis, X-ray diffraction, IR and UV spectroscopy). The crystal and molecular structure of Cu(NEHA)2 was solved using X-ray diffraction. The composition and stability constants of the complexes in solutions were determined spectrophotometrically. The organic ligands were shown to be coordinated to the metal cation in the bidentate chelate mode in the anionic form.

Interaction of copper(II) halides with 4-(piperidyl-1)-2-phenylpyrido[2,3-a]anthraquinone-7,12 (L) in acidic media: Crystal structure and spectral characteristics of (HL)2[Cu2Cl6] and (HL)[CuBr2]

Abstract4-(Piperidyl-1)-2-phenylpyrido[2,3-a]anthraquinonium-7,12 hexachlorodicuprate(II) and 4-(piperidyl-1)-2-phenylpyrido[2,3-a]anthraquinonium-7,12 dibromocuprate(I) are isolated in the crystalline state and investigated using X-ray diffraction. It is established that the Cu(II) cation is reduced to the Cu(I) cation during the synthesis of anionic bromocuprate complexes in the presence of hydrobromic acid. The spectral characteristics of the prepared compounds are discussed.

Coordination chemistry of polyoxo-carbocyclic compounds containing one or more neighboring oxo-groups

Abstract This is a review of publications concerning the results of X-ray analysis of single crystals and spectrochemical characteristics of metal complexes containing polyoxo-carbocyclic compounds with one or more neighboring oxo-groups. The features of lattice characteristics and coordination modes, depending on the nature of the organic dianion, are shown here. The squarate anions, C4O42-

Hexaaquacobalt(II) and hexaaquacadmium(II) 4-nitro-2,3,5,6-tetraoxopyridinates [M(H2O)6](C5HN2O6)2 · 2H2O (M = Co and Cd): Synthesis, structures, and properties

{{\rm{C}}_{\rm{4}}}{\rm{O}}_{\rm{4}}^{{\rm{2 - }}}

catena-Poly[ammonium [aqua­bis­(μ-2,3,5,6-tetra­oxo-4-nitro­pyridin-4-ido)argentate(I)]]

are predominantly involved in monodentate bridging coordination, and the derivatives containing five or six C-atoms in the cycle (croconate and rhodizonate anions) usually form bidentate chelating bridged modes. The stabilization of the crystal lattices of the metal complexes is due to the formation of hydrogen bonds and π-π stackings, which produce self-assembled three-dimensional (3D) structures with cavities and intercalation of some small molecules. The strong interlayer interactions lead to appearance of specific conductometric and magnetic properties, which together with their high thermal stabilities, make the oxocarbon complexes new and perspective materials for electronics and related areas.

Synthesis and the crystal and molecular structures of (H3L · Cl)[CoCl4] and H2L[CuBr4] (L is 2,4,6-Tri(N,N-dimethylamino)methylphenol)

The complexes [Cd(H2O)6](C5HN2O6)2 · 2H2O (I) and [Co(H2O)6](C5HN2O6)2 · 2H2O (II) were obtained in the crystalline state by reactions of cobalt chloride and cadmium chloride with ammonium 4-nitro-2,3,5,6-tetraoxopyridinate, (NH4)2 · (C5HO6N2)2. Their cocrystallization gave the heterometallic complex [Cd0.32Co0.68(H2O)6](C5HN2O6)2 · 2H2O (III). The crystal and molecular structures of complexes I-III were determined by X-ray diffraction. It was demonstrated that the complexation reactions occur by replacement of two ammonium cations 4-nitro-2,3,5,6-tetraoxopyridinate by the complex cations [M(H2O)6]2+. The tetraoxopyridinate anions and the complex cations are hydrogen-bonded through the coordinated and crystallization water molecules as well as through the O atoms of the organic anion. The thermolysis of complexes I and II was examined by TGA.