Investigation of electronic interactions in solid hydrogen fluoride

Intermolecular interactions in solid hydrogen fluoride are studied by the combined quantum chemical and X- ray diffraction method. The structure of crystalline HF is modeled by (HF)_n chains (n =2, 3,...,20, by an (HF)₄₅ cluster consisting of five (HF)₉ chains, and by an (HF)₁₀₈ cluster consisting of twelve (HF)₉ chains with nearly zero dipole moment. The quantum chemical calculations of the clusters are performed by the semiempirical AM1 method, which is most suitable for electronic structure investigations of hydrogen fluoride, as shown by comparing the X- ray experimental and theoretical spectra. The theoretical X- ray spectra are also compared with the experimental FK_α spectra of gaseous and solid hydrogen fluoride. For more detailed studies of electronic interactions in crystalline HF, fragrnent analysis of MOs of the clusters with respect to the MOs of the central molecule is carried out. Translated fromZhumal Strukturnoi Khimii, Vol. 38, No. 4, pp. 686–695, July–August, 1997.     

Electronic structure and spectra of [Ru(NH3)5pyz]2+ and [(NH3)5Ru-pyz-Ru(NH3)5]4+

The electronic structure and spectra of [Ru(NH₃)₅pyz]²⁺ and [(NH₃)₅Ru-pyz-Ru(NH₃)₅]⁴⁺ are calculated by the INDO (CINDO-E/S) method. Changes in molecular orbitals, charge distributions, and bond order indices of the pyrazine molecule and [Ru(NH₃)₅pyz]²⁺ complex in the [(NH₃)₅Ru-pyz-Ru(NH₃)₅]⁴⁺ binuclear complex are analyzed. St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 4, pp. 12–23, July–August, 1994. Translated by. O. Kharlamova     

Semiempirical calculations of the electronic spectra of organometallic compounds: Estimation of solvent and counterion effects

The electronic spectra of the [Ru(NH₃)₅pz]²⁺, [Ru(NH₃)₅pz]³⁺, and [Ru(CN)₅pz]³⁻ complexes are calculated by the CI INDO method. The effect of solvation on the spectra is considered in a point charge approximation and in terms of the parametric model of a charged sphere enveloping the metal fragment. Interrelation of these approaches is discussed. Data on the molecular electrostatic potentials created by the complexes are presented to substantiate the models. St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 4, pp. 603–618, July–August, 1996. Translated by I. Izvekova     

Stretching vibrations and structure of (HF) n (n=4–8) clusters

IR spectra of 24 structural isomers of (HF) _n (n=4–8) clusters were calculated in the framework of semiempirical theory of polyatomic molecule vibrations. Based on the results obtained and available experimental data it is proposed that (HF) _n associates comprising 3–5-membered cycles with attached monomeric HF units are present in molecular beams and gas phase.Ab initio calculations performed by the SCF method show the existence of local minima corresponding to such structures on the potential energy surface of (HF) _n clusters (n=4–6). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 435–443, March, 1997.     

Structure of X-ray photoelectron and X-ray emission spectra of ThO2 and ThF4 due to electrons of molecular orbitals

The fine structure of the X-ray photoelectron and O_4,5(Th) X-ray emission spectra of the low-energy (0 …) ∼50eV) electrons of thorium in ThO₂ and ThF₄ is studied. It is established that both outer (0 … ∼15 eV) and inner (15… ∼50 eV) valence molecular orbitals, which are mostly due to the Th6p and O(F)2s shells of the neighboring thorium atoms and ligands, are formed in these compounds. Translated fromZhumal Struktumoi Khimii, Vol. 39, No. 6, pp. 1052–1058, November–December, 1998.     

Semiempirical calculations of the electronically excited states of organometallic compounds: Selection of configuration interaction basis sets

Semiempirical INDO-E/S+RCIP calculations of the electronic structures of the ground and excited states of the pyrazine (pz) molecule and [Ru(NH₃)₅pz]^q (q=+1, +2, +3) complexes were performed to analyze the dependence of the calculation results on the active MO space and configuration basis set. Recommendations for the construction of the {Ф_k} basis sets and formation of the {ϕ_k} sets are given. St. Petersburg State University. Translated fromZhurnal Struktumoi Khimii, Vol. 37, No. 2, pp. 206–219, March–April, 1996. Translated by I. Izvekova     

Clathrate formation in the liquid phase of (C4H9)4NF−NH4F−H2O

At a certain concentration of NH₄F, the solid allocyric solutions of the (C₄H₉)₄NF−NH₄F−H₂O system stratify into two liquid phases in the process of melting. The mutual solubility of the liquids decreases at elevated temperatures. The boundary surface of the stratification region was determined The solubility isotherms (27 and 30°C) of the stratification region are investigated by the solubility method This relatively rare mutual sulubility of liquids (retrograde solubility) is associated with clathrate formation in the liquid phase. Near the melting points of the solid clathrate solutions, both in the liquid and solid phases the tetrabutylammonium cation evidently forms surrounding cavities bounded by water and ammonium fluoride molecules linked by hydrogen bonds. The clathrate-like components of the solution are structurally compatible with “water-like” and “organic” components, i.e., they are homogenizing components. At higher temperatures, the homogenizing clathrate-like structures break down, and the structurally incompatible solution components stratify into two phases. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol 35, No. 6, pp. 122–128, November–December, 1994. Translated by L. Smolina     

X-ray fluorescent and EXAFS studies of the electronic and spatial structure of dialkyl sulfides and their PdCl2 complexes in extraction systems

SK_α, SK_β, ClK_β, ClK_β, and PdL_β2 X-ray fluorescent and PdK EXAFS spectra were obtained for some organic solutions of dialkyl sulfide complexes with palladium chloride. Solvent effects on the electronic and spatial structure of complexes in solution are discussed. In the benzene solution of [PdCl₂2(C₆H₁₃)₂S], complex molecules interact with solvent molecules along a coordinate that is perpendicular to the plane of the complex molecule. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurmal Strukturnoi Khimii, Vol. 35, No. 4, pp. 105c111, July–August, 1994. Translated by L. Smolina     

Manifestation of electron-nuclear motions in the123Sb NQR spectra of pentafluoroantimonites

A dependence between the quadrupole coupling constants (e ² Qq _zz ) and the asymmetry parameters of the electric field gradient (η) for the antimony atoms in the complex [SbF₅]²⁻ anions of M₂SbF₅ pentafluoroantimonites (M=Na, K, Rb, Cs, NH₄, Ti, and Et₂NH₂) was revealed from the¹²³Sb NQR spectra at 77 K. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1988–1990, October, 1998.     

Anisotropy of lattice distortion in [Co(NH3)5ONO]X2, X=Cl−, Br−, under hydrostatic pressure of up to 5.0 GPA

Variation of the unit cell parameters of [Co(NH₃)₅ONO]X₂ (X=Cl⁻, Br⁻) as a function of hydrostatic pressure is studied by powder X-ray diffractometry in cooled diamond anvils. Pressures of up to 5.0 GPa lead to anisotropic lattice distortion but not to phase transitions. The anisotropy of lattice compression of the nitrito isomers is qualitatively distinct from that of the related structures of the corresponding nitro isomers, which differ mainly in the structure of complex cations. The following specific interactions are responsible for the anisotropy of compression for both nitrito and nitro isomers: hydrogen bonds between the NO₂ and NH₃ ligands of the neighboring cations and between the NH₃ ligands and the halide anions; specific interactions of the NO₂ ligands of the neighboring cations with each other and of the NO₂ ligands with the halide anions. Institute of Solid State Chemistry, Siberian Branch, Russian Academy of Sciences. Novosibirsk State University. Institute of Mineralogy and Materials Science and Technology Center, Marburg University (Germany). Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 3, pp. 424–432, May–June, 1998. This work was supported by the Humboldt Foundation (Germany) and the “Universities of Russia” Program (projects 3H-34-94, 3H-375-92).     

Joint X-ray spectroscopic and quantum-chemical study of the electronic structure of pentafluorophenylalkyl ethers

The high resolution X-ray emission O-Kα spectra of pentafluorophenylalkyl ethers C₆F₅OR (R=Et, Prⁱ, and Bu^t) exhibit differences related to a change in the electronic structure of the compounds as R is varied. The search for stable conformers was performed by the semiempirical PM3 method. The most probable structures of C₆F₅OR were determined by the comparison of the experimental and theoretical X-ray spectra plotted for each conformer usingab initio calculations in the 6–31 G basis set. Substituent R in pentafluorophenylalkyl ethers is situated outside of the ring plane. The fluorination of the benzene ring changes the energy level of the lone electron pair of oxygen relative to the levels of orbitals of the ring and substituent R and leads to an increase in the efficiency of interactions in the σ-system. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2443–2450, December, 1998.     

Interaction of platinum fulleride C60Pt with deuterium

X-ray photoelectron spectra and catalytic properties of platinum fulleride C₆₀Pt were studied. The value of the bond energy of Pt4f_7/2 (72.4 eV) found for platinum in the starting C₆₀Pt suggests a partial charge transfer from Pt to C₆₀. The interaction of solid platinum fulleride with gaseous deuterium leads to the formation of fullerene deuterides C₆₀D _x and Pt clusters. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 999–1002, May, 1999.     

Computer simulation of the structure of the hydration shells of calcium and calcium-water-zeolite a

A potential function is suggested to describe the interaction of the calcium ion with the water molecule using the tetrahedral model of the water molecule. Monte Carlo simulations of small clusters Ca(H₂O)_n (n≤20) and analyses of the resulting F-structures showed that the coordination number of Ca is 8. The structure of water adsorbed in the α-cavity of zeolite CaA depends predominantly on interactions with Ca²⁺ ions. The water molecule forms one hydrogen bond with an oxygen atom of the framework; the molecules are not hydrogen-bonded with each other. In this respect the structure of water in the Ca form of zeolite A resembles that in the Na form but differs from that in the K form. Institute of Physical Chemistry, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 1, pp. 88–97, January–February, 1996 Translated by L. Smolina     

A Theoretical Study of Amine Bonding in Titanium Alkoxide Adducts

Summary. DFT calculations were carried out on Ti₂(OCH₃)₈ (NH₂CH₃)₂ and Ti₂(OCH₃)₈(NH₃)₂, which are model compounds for the previously isolated amine adducts Ti₂(OR)₈(NH₂ R′)₂. The calculations show that the Ti–N bond strength is weak; however, coordination of the amine to the metal center is supported by a N–H···O hydrogen bond of the amine with the neighboring alkoxo ligand. The Ti–N interaction is purely σ in nature, while the Ti–O interactions include both σ and π contributions. The lowest unoccupied molecular orbitals are mainly localized on Ti t_2g-like orbitals.     

Synthesis, structure, and properties of [RuNO(NH3)4OH][PtCl4] and [RuNO(NH3)4OH][PdCl4]

Double complex [RuNO(NH₃)₄OH][PtCl₄] (I) and [RuNO(NH₃)₄OH][PdCl₄] (II) salts have been prepared and explored with TGA, IR spectroscopy, powder and single crystals X-ray diffraction. Crystal phases of I and II are isostructural (space group Cmc2₁) and have the following crystal chemical characteristics: a = 8.106 Å, b = 18.190(3) Å, c = 8.097 Å, V = 1194.0 ų, Z = 4, ρ_calc = 3.077 g/cm³ (I), and a = 8.116 Å, b = 18.135 Å, c = 8.062 Å, V = 1186.5 ų, Z = 4, ρ_calc = 2.600 g/cm³ (II). The product of thermal decomposition of I in inert and hydrogen atmospheres is a substitution solid solution Pt_0.5Ru_0.5 with the parameter of the FCC unit cell a = 3.856(3) Å. Thermolysis of II affords two-phase mixtures of limited solid solutions of the metals featuring Ru-based HCP and Pd-based FCC cells. __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No.1, pp.114–121, January–February, 2007.     

Electronic structure and properties of the ground state of copper in semiconducting cuprates

The spin-polarized discrete variational X_a method is used to calculate clusters that model the electronic structures of CuO, La₂CuO₄, and Nd₂CuO₄. It, is shown that in each of the compounds the unoccupied portion of the valence band involves mainly the O2p states, the contributions from the Cu3d orbitals being significantly smaller. The effects of the nature of holes in the valence band and of the structure of the close environment of copper on the low-energy CuK spectra and the X-ray photoelectron spectra of the above systems are discussed. Institute of Solid State Chemistry, Ural Branch, Russian Academy of Sciences. Translated fromZhumal Struktumoi Khimii, Vol. 36, No. 4, pp. 636–643, July–August., 1995. Translated by I. Izvekova     

X-ray diffraction study of [Ru(NH3)5Cl][ReCl6] and [Ru(NH3)5Cl]2[ReCl6]Cl2 and their thermolysis products. Crystal-chemical analysis of the Ru-Re system

Binary complex salts [Ru(NH₃)₅Cl][ReCl₆] and [Ru(NH₃)₅Cl]₂[ReCl₆]Cl₂ were synthesized and characterized. An X-ray diffraction analysis showed that they were isostructural with the previously obtained isoformula salts [Rh(NH₃)₅Cl][OsCl₆] and [Ir(NH₃)₅Cl]₂[PtCl₆]Cl₂, respectively. Thermolysis of these compounds under hydrogen and helium was studied. According to X-ray phase analysis data, bimetallic solid solutions Ru_0.67Re_0.33 and Ru_0.50Re_0.50 were the final products of thermolysis. Their unit cell parameters correspond to the characteristics of alloys with similar compositions. Original Russian Text Copyright ? 2009 by S. A. Martynova, K. V. Yusenko, I. V. Korolkov, I. A. Baidina, and S. V. Korenev __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 1, pp. 126–132, January–February, 2009.     

X-ray spectra and electronic structure of several ternary chalcogenides and their solid solutions

The electronic energy structure of substitution solid solutions CuGa(S_xSe_1−x)₂ is studied within wide limits of sulfur concentration x in the onion sublattice. The SK absorption spectrum is calculated for CuGaS₂ in a high-order multiple scattering approximation using the FEFF7 program. For all concentrations x, partial densities of states are calculated in a full multiple scattering approximation by the local coherent potential method. The calculation schemes for the filled and vacant states are employed, which differ in a choice of the crystalline potential. The effect of a vacancy on the SK level on the density of the free Sp states is considered. The theoretical K absorption spectra and densities of states of CuGaS₂ are compared with the experimental X-ray and X-ray photoelectron spectra. The calculated curves are in good agreement with the experiment. It is established that the densities of the S and Se p states change smoothly with varying concentration of anions. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 6, pp. 1076–1082, November–December, 1998.     

A new chiral coordination polymer based on [Fe(CN)6]4?, Cu2+ cations, and (2 S , 3 S )-1,2,3,4-tetraaminobutane: Synthesis, structure, and ESR spectra

The new chiral coordination polymer [{Cu(NH₃)(threo-tab)}₂Fe(CN)₆]·8H₂O was synthesized by the reaction of an aqueous solution of potassium hexacyanoferrate with an ammonia solution of copper(II) chloride and (2S,3S)-1,2,3,4-tetraaminobutane (threo-tab). The structure of the coordination polymer was established by X-ray diffraction. The ESR spectra of this compound were measured for a powder and a single crystal. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 437–440, March, 2007. Universit?t des Saarlandes, Anorganische Chemie, Saarbrücken, Germany.     

Investigation of phase transitions of a pseudo-hexagonal phase of [Rh(NH3)5Cl]2[Re6S8(CN)6]·3H2O during thermal decomposition

A general motif of the crystal structure of [Rh(NH₃)₅Cl]₂[Re₆S₈(CN)₆]·3H₂O is examined, and the cluster anions are found to form a pseudo-hexagonal sublattice. The thermal decomposition of [Rh(NH₃)₅Cl]₂[Re₆S₈(CN)₆]·3H₂O is studied, and it is shown that in helium atmosphere thermolysis occurs through the formation of intermediate amorphous phases. The final product obtained at 1200°C is a disordered single-phase solid solution of Re_0.75Rh_0.25 based on the structure of rhenium. Powder X-ray diffraction data for solid solutions in the system of Rh-Re are surveyed. It is demonstrated that the data for phases prepared by the thermal decomposition of coordination compounds better match the theoretical state diagram than the experimental one. The dependence of atomic volume on the composition of solid solutions of Re_xRh_1−x is derived. Original Russian Text Copyright ? 2007 by S. A. Gromilov, K. V. Yusenko, and E. A. Shusharina __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No.5, pp.957–962, September–October, 2007.