Synthesis and structures of Cs4[(UO2)2(C2O4)(SO4)2(NCS)2] · 4H2O and (NH4)4[(UO2)2(C2O4)(SO4)2(NCS)2] · 6H2O

Single crystals of Cs₄[(UO₂)₂(C₂O₄)(SO₄)₂(NCS)₂] · 4H₂O (I) and (NH₄)₄[(UO₂)₂(C₂O₄)(SO₄)₂(NCS)₂] · 6H₂O (II) have been synthesized and studied by X-ray diffraction. The crystals of both compounds are orthorhombic with the space group Pbam, Z = 2, and unit cell parameters a = 12.0177(3) ?, b = 18.6182(5) ?, c = 6.7573(10) ?, R = 0.0376 (I); a = 11.6539(9) ?, b = 18.3791(13) ?, c = 6.7216(5) ?, R = 0.0179 (II). The main structural units of crystals I and II are [(UO₂)₂(C₂O₄)(SO₄)₂(NCS)₂]⁴⁻ chains belonging to the crystal-chemical group A₂K⁰²B₂²M₂¹ (A = UO₂²⁺, K⁰² = C₂O₄²⁻, B² = SO₄²⁻, M¹ = NCS⁻) of the uranyl complexes. The uranium-containing chains are joined into a three-dimensional framework due to a system of electrostatic interactions with the cesium or ammonium ions in the structure of I. In the structure of II, this framework is additionally stabilized by hydrogen bonds involving the outer-sphere water molecules and ammonium ions. Original Russian Text ? I.V. Medrish, A.V. Virovets, E.V. Peresypkina, L.B. Serezhkina, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 7, pp. 1115–1120.     

Oxidative addition of the Mo-Cl bond to the Pt0 complex. Synthesis and structure of Cp′Mo(μ-CO)2(C2Ph2)Pt2(PPh3)2(CO)Cl

A reaction of Cp′Mo(CO)₃Cl(Cp′ = MeC₅H₄) with (PPh₃)₂Pt(C₂Ph₂) gave the heterometallic cluster Cp′Mo(μ-CO)₂(C₂Ph₂)Pt₂(PPh₃)₂(CO)Cl (I) as the sole product. According to X-ray diffraction data, complex I contains single Pt-Mo bonds (2.7962(5) and 2.7699(5) ?) but no Pt-Pt bond (Pt…Pt 2.9746(3) ?). The coordinated diphenylacetylene molecule forms two Pt-C σ-bonds (2.054(6) and 2.083(5) ?) and a π-bond to the Mo atom (Mo-C 2.265(6) and 2.272(5) ?; C≡C 1.387(8) ?). Original Russian Text ? A.A. Pasynskii, I.V. Skabitskii, Yu.V. Torubaev, S.S. Shapovalo, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 6, pp. 410–413.     

Formation of Co nanoparticles in the process of thermal decomposition of the cobalt complex with hexamethylenetetramine (NO3)2Co(H2O)6(HMTA)2 · 4(H2O)

The thermal decomposition of the cobalt complex with hexamethylenetetramine (NO₃)₂Co(H₂O)₆(HMTA)₂ · 4(H₂O) was studied by the methods of differential thermal analysis, thermogravimetry, mass spectrometry, X-ray diffraction analysis, and by the magnetic method. It was established that the thermal decomposition of the complex in a current of an inert gas is accompanied by a pronounced exothermic process and formation of Co nanoparticles. It was shown that the kinetics of this process and the chemical nature of the decomposition products depend on the initial density of the sample under study.     

Heat capacity and thermodynamical properties of the crystal of [RE2(Glu)2(H2O)8](ClO4)4·H2O (RE = Nd, Eu, Dy)

Thermodynamical data of rare earth complexes with amino acid are important for engineering chemistry and fundamental chemistry. However, they have rarely been reported. In this work, a series of crystalline complexes of rare earth perchlorate coordinated with glutamic acid have been synthesized in water medium, and their thermodynamical data, including the heat capacity in low temperature range and the standard enthalpy of formation, were determined. These complexes were identified to be [RE₂(Glu)₂(H₂O)₈](ClO₄)₄·H₂O (RE = Nd, Eu, Dy) by using thermogravimetric analysis (TG), differential thermal analysis (DTA), and chemical and elementary analyses. Their purity has been determined. No melting points were observed for all the three complexes. The heat capacity of the complexes was measured by an adiabatic calorimeter from 79 to 370 K. Abnormal heat capacity values were detected for two of the complexes and the decomposition range of one complex was found. The temperature, enthalpy change and entropy change of the decomposition processes of the three complexes were calculated. The polynomial equations of heat capacity in the experimental temperature range have been obtained by least squares fitting. The standard enthalpy of formation was determined by an isoperibol reaction calorimeter at 298.15 K. Supported by the Research Fund of Beijing Institute of Petro-Chemical Technology (N06-06)     

Crystal structure of K2[Mo3(PdPPh3)S4(C2O4)3(H2O)3]·0.5H2O

By the reaction of [Mo₃S₄(C₂O₄)₃(H₂O)₃]²⁻ with PdCl₂ and NH₄H₂PO₂ as a reducing agent, followed by the addition of PPh₃, a new oxalate cuboidal cluster complex [Mo₃(PdPPh₃)S₄(C₂O₄)₃(H₂O)₃]²⁻ is obtained. It was isolated and structurally characterized as K₂[Mo₃(PdPPh₃)S₄(C₂O₄)₃(H₂O)₃]·0.5H₂O. Original Russian Text Copyright ? 2008 by A. L. Gushchin, M. N. Sokolov, D. Yu. Naumov, and V. P. Fedin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 4, pp. 775–778, May–June, 2008.     

Specifics of pyrohydrolytic and solid-phase syntheses of solid solutions in the (MgGa2O4)x(MgFe2O4)1 ? x system

This work demonstrates the possibility of preparing solid solutions in the (MgGa₂O₄) _x (MgFe₂O₄)_{1 − x} system by pyrohydrolytic and solid-phase methods. It is shown that the products obtained have different specific surface areas depending on the ratio between metal nitrates and citric acid. The composition dependence of the unit cell parameter deviates considerably from the Vegard’s rule. The compounds obtained are found to be stable up to 300°C, which makes them candidate materials for electronics.     

Gas-phase measurements of the surface basicity of AlPO4?TiO2 and AlPO4?ZrO2 catalysts

The amount and strength of basic sites of AlPO₄–TiO₂ and AlPO₄–ZrO₂ catalysts over a different range of AlPO₄/metal oxide weight ratios were measured by studying the adsorption of acid molecules (acrylic acid and phenol) in the gas phase (473–673 K) by using the gas-chromatographic pulse method. The results obtained show that the basicity of AlPO₄–TiO₂ and AlPO₄–ZrO₂ catalysts is far lower than that of pure AlPO₄, and with an increase in the metal oxide (TiO₂ or ZrO₂) weight ratio, the basicity decreases. Besides, the basicity of AlPO₄–ZrO₂ is fairly low compared with that AlPO₄–TiO₂. In both cases, the total basicity (measured at 473 K vs. acrylic acid) gradually decreases with the calcination temperature while the stronger basic sites (measured at 573 K vs. phenol) remained unchanged up to calcination temperatures of 1073 K. Some weak surface basic sites remained in catalysts pretreated at 1273 K.

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- AlPO₄–TiO₂ AlPO₄–ZrO₂ AlPO₄/ , ( ) (473–673 K). , AlPO₄–TiO₂ AlPO₄–ZrO₂ AlPO₄ TiO₂ ZrO₂. , AlPO₄–ZrO₂ AlPO₄–TiO₂. — 473 K — , , 573 K , 1073 K. , 1273 K, .

     

Formation of the silylene-bridged complex Fe2(CO)6(μ2-SiCl2)3 from cis-Fe(CO)4(SiCl3)2: an experimental and computational study

Abstract  

Thermolysis of cis-Fe(CO)₄(SiCl₃)₂ results in the formation of the novel compound Fe₂(CO)₆(μ₂-SiCl₂)₃, which was characterized by single crystal X-ray diffraction. Density functional theory calculations were carried out to elucidate possible reaction steps leading to the formation of Fe₂(CO)₆(SiCl₂)₃, including CO dissociation and chlorine abstraction by a SiCl₃ radical generated from homolytic Fe–Si bond cleavage involving a singlet–triplet intersystem crossing.     

Synthesis and X-ray crystal structure of the dinuclear copper(I) complex [Cu2((Me-Pk)2En)(PPh3)4](ClO4)2 · 2CHCl3

The new dinuclear copper(I) complex, [Cu₂((Me-Pk)₂En)(PPh₃)₄](ClO₄)₂ · 2CHCl₃ (I), where (Me-Pk)₂En = N,N′-bis(1-pyridin-2-yl-ethylidene)ethane-1,2-diamine), has been synthesized and characterized by elemental analyses, FT-IR, and single-crystal X-ray diffraction method. In this complex, two Cu(PPh₃)₂ units are connected by one (Me-Pk)₂En bridging ligand. The coordination geometry around each copper(I) atom is a distorted tetrahedron formed by two N atoms from (Me-Pk)₂En and two P atoms from the PPh₃ ligands. The distance between two copper atoms is 7.06(1) ?.     

Effect of the solvent on the hydrolysis of the iron nitrosyl complex {Fe2[S(CH2)2NH3]2(NO)4}SO4·2.5H2O: spectroscopic and kinetic investigations of its monomer and dimer forms

The hydrolysis of the iron nitrosyl complex {Fe₂[S(CH₂)₂NH₃]₂(NO)₄}SO₄·2.5H₂O (CysAm) in water is not accompanied by the formation of its monomer form and is a reversible process. According to the ESR, ¹H NMR, and spectrophotometric data, the dissolution of CysAm in DMSO affords the monomer form of CysAm. The kinetic parameters of the hydrolysis of CysAm in the dimer and monomer forms were determined by kinetic modeling.     

A kinetic investigation of the oxidative addition reactions of the dimeric Bu4N[Ir2(μ-Dcbp)(CO)2(PCy3)2] complex with iodomethane

The IR and UV/visible kinetic results of the oxidative addition of iodomethane to Bu₄N[Ir₂(μ-Dcbp)(CO)₂(PCy₃)₂] (Dcbp = 3,5-dicarboxylatepyrazolate anion) showed three time separable reactions. The first, very fast reaction corresponds to the a Ir(I)-Ir(III) alkyl species formation within 10⁻³ s. The second, relative fast reaction corresponds to Ir(III)-Ir(III) alkyl formation with a rate constant of 3.25(4) × 10⁻² M⁻¹ s⁻¹ while the third and slowest reaction corresponds to Ir(III)-Ir(III) acyl formation with a rate constant of 1.42 × 10⁻⁵ s⁻¹. The IR data clearly show the existence of a number of equilibria with the formation of an Ir(I)-Ir(III) alkyl product which then react to form the Ir(III)-Ir(III) which then slowly react to form the Ir(III)-Ir(III) acyl product. A solvent study indicated increased oxidative addition activity in the presence of polar solvents, which is indicative of a polar transition state. The large negative entropy of activation for the Ir(III)-Ir(III) alkyl formation step (k₂) of −178(23) JK⁻¹ mol⁻¹ is indicative of an associative process. DFT calculations successfully identified the stereochemistry of the starting complex, [Ir₂(μ-Dcbp)(CO)₂(PCy₃)₂]⁻ as well as that of the Ir-alkyl and acyl isomers. A reaction pathway, using the IR data and DFT calculations, is proposed for the reaction.     

Synthesis, crystal structure and luminescence of a novel metal-organic polymer {Cd2(C4H2O4)2(C4H6N2)2(H2O)2 · 2H2O}n

The novel 3D coordination polymer {Cd₂(C₄H₂O₄)₂(C₄H₆N₂)₂(H₂O)₂ · 2H₂O} _n (I) has been synthesized and characterized by standard solid state methods including single-crystal X-ray crystallography. The compound crystallizes in triclinic space group P [`1]\bar 1 with a = 8.589(4), b = 10.585(3), c = 13.094(1) ?, α = 84.91(4)°, β = 79.21(0)°, γ = 83.76(4)°, V = 1159.5(1) ?³, Z = 2. The fumaric acid acts as a multimodal bridging ligand in the polymer unit. One of the fumaric acid ligands tridentately chelates to two Cd²⁺ cations in the same dinuclear unit, while the other bidentately chelates to two Cd²⁺ cations in another dinuclear unit. The two metal centers possess slightly distorted pentagonal bipyramid geometry with four Cd {(μ₄-fumarato)-(μ₂-fumarato)-bis(2-methylimidazolyl)-diaqua} units joining together to form a 28-membered ring. The whole molecule exhibits a through channel along y-axis and 2D layers in xz plane. With hydrogen bond and π-π interaction, the 2D layers construct a 3D microporous network.     

Phase formation in Li2MoO4-Rb2MoO4-MMoO4 (M = Ca, Sr, Ba, Pb) systems and the crystal structure of α-Rb2Pb(MoO4)2

A subsolidus triangulation of Li₂MoO₄-Rb₂MoO₄-MMoO₄ (M = Ca, Sr, Pb, Ba) systems is performed. The RbLiMoO₄-Rb₂M(MoO₄)₂ (M = Pb, Ba) joins, where 11 mol.% long Rb₂M(MoO₄)₂-based solid solutions are found, are studied in most detail. Ternary molybdates do not form in the systems, which is confirmed by spontaneous flux crystallization. The α-Rb₂Pb(MoO₄)₂ crystals are obtained and their crystal structure is solved (a = 20.9724(15) ?, b = 12.1261(8) ?, c = 16.1171(10) ?, β = 115.728(13)°, C2/m space group, R = 0.0695, Z = 16), which is a monoclinic superstructure of the palmierite type and has the largest cell volume and the most complex structure among lead-containing palmierites. One of the MoO₆ tetrahedra is orientationally disordered over two sites; lead atoms are shifted from the centers of their coordination polyhedra to one of their faces and have cn = 6–8; for rubidium cations cn = 10–12.     

Synthesis and characterization of a new octamolybdate (NH4)4[Mo8O24(C3H2O2)2] · 4H2O

A new complex with the formula (NH₄)₄[Mo₈O₂₄(C₃H₂O₂)₂] · 4H₂O (1) has been synthesized and characterized by single crystal X-ray diffraction and infrared spectrum. The complex is small yellow crystal and space group P ₁ with a = 9.9869(18) ?, b = 10.030(19) ?, c = 10.366(19) ?, α = 91.68(3)°, β = 98.94(3)°, γ = 119.37(2)°, V = 887(3) ?³, and Z = 1. The complex contains two malonic acid ligands bonded to the γ-Mo_{8 26}⁴⁻ ions which consist of eight MoO₆ edge-sharing octahedral. In this crystal structure, the octamolybdate anion is mutually hydrogen bonded by ammonium ions and water molecules.     

Cr2(WO4)3和Cr2(MoO4)3的负热膨胀特性研究

用液相反应-前驱物烧结法制备了Cr₂(WO₄)₃和Cr₂(MoO₄)₃粉体。298～1 073 K的原位粉末X射线衍射数据表明Cr₂(WO₄)₃和Cr₂(MoO₄)₃的晶胞体积随温度的升高而增大, 本征线热膨胀系数分别为(1.274±0.003)×10^-6 K^-1和(1.612±0.003)×10^-6 K^-1。用热膨胀仪研究了Cr₂(WO₄)₃和Cr₂(MoO₄)₃在静态空气中298～1 073 K范围内热膨胀行为，即开始表现为正热膨胀，随后在相转变点达到最大值，最后表现为负热膨胀，其负热膨胀系数分别为(-7.033±0.014)×10^-6 K^-1和(-9.282±0.019)×10^-6 K^-1。     

[COH(NH2)2]2[Cu(pic)2(ClO4)2]的合成与晶体结构

The title compound was synthesized by reaction of Cu(ClO₄)₂， picolinic acid and carbamide in C₂H₅OH/CH₃CN solution， and characterized by single-crystal X-ray diffraction. It crystallizes in the orthorhombic system， space group Pbca with a=14.0481(8)， b=9.0130(5)， c=18.626(1)?， V=2358.3(2)?³， Z=4， D_x=1.771g·cm^-3， μ=1.235mm^-1 and F(000)=1276. The final R factor is 0.0440 for 1434 observed reflections. The X-ray analysis revealed that the copper(Ⅱ) atom is coordinated by two picolinic ligands in the equatorial plane， while the two oxygen atoms of perchlorate occupy the axial positions of octahedron with lengthened Cu-O distances， resulting in a 4+2 elongated octahedral environment. In the compound， there also exist two protonated carbamide cations for charge balance. CCDC： 195354.     

1H NMR refinement of the structure of the guest sublattice and molecular dynamics in the ultrathin channels of [Zn2(C8H4O4)2(C6H12N2)]·n(H3C)2NCHO

Localization and molecular mobility of the ligands ([C₈H₄O₄]²⁺ and [C₆H₁₂N₂]⁰) of the host lattice and (CH₃)₂NCHO dimethyl formamide guest molecules in the inclusion compound [Zn₂(C₈H₄O₄)₂(C₆H₁₂N₂)]·n(H₃C)₂NCHO were studied on the basis of ¹H NMR data. At room temperature, the longest axes of the dimethyl formamide guest molecules are ordered in parallel to the C ₄ symmetry axes, and the symmetry planes of these molecules are disordered, while preserving the tetragonal crystal system of the inclusion compound. At lower temperatures, a phase transition takes place in view of the ordering in the guest sublattice. Original Russian Text Copyright ? 2009 by A. V. Sabylinskii, S. P. Gabuda, S. G. Kozlova, D. N. Dybtsev, and V. P. Fedin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 50, No. 3, pp. 443–450, May–June, 2009.     

Synthesis and crystal structure of (C3N5H6S)2[UO2(C2O4)2(H2O)] · C2N4H4

The formation of the thioammelinium cation in an aqueous solution in the presence of uranyl ions is demonstrated. Single crystal X-ray diffraction study of (C₃N₅H₆S)₂[UO₂(C₂O₄)₂(H₂O)] · C₂N₄H₄ was carried out and the geometric characteristics of thioammelinium were determined for the first time. The crystals are triclinc, space group , Z = 2, a = 8.5201(11) ?, b = 11.4027(14) ?, c = 14.329(2) ?, α = 103.182(5)°, β = 99.607(6)°, γ = 109.698(4)°, R = 0.0526. The main structural units in the crystal are mononuclear complex groups [UO₂(C₂O₄)₂(H₂O)]²⁻ corresponding to the crystal chemical group AB ₂ ⁰¹ M¹ (A = UO ₂ ²⁺ , B⁰¹ = C₂O ₄ ²⁻ , M¹ = H₂O) of uranyl complexes. Uranium-containing mononuclear complexes are connected into a three-dimensional framework through electrostatic interactions and hydrogen bonds involving thioammelinium ions, water molecules, and cyanoguanidine. Original Russian Text ? L.B. Serezhkina, A.V. Virovets, E.V. Peresypkina, I.V. Medrish, 2007, published in Koordinatsionnaya Khimiya, 2007, Vol. 33, No. 5, pp. 380–385.