Crystal structure of Cs[(UO<Subscript>2</Subscript>)<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(OH)] · H<Subscript>2</Subscript>O

Single crystals of Cs[(UO₂)₂(C₂O₄)₂(OH)] · H₂O were synthesized and structurally studied using X-ray diffraction. The compound crystallizes in monoclinic space group P2₁/m, Z = 2, with the unit cell parameters a = 5.5032(4) Å, b = 13.5577(8) Å, c = 9.5859(8) Å, β = 97.012(3)°, V = 709.86(9) ų, R = 0.0444. The main building units of crystals are [(UO₂)₂(C₂O₄)₂(OH)]^? layers of the A₂K ₂ ⁰² M² (A = UO ₂ ²⁺ , K⁰² = C₂O ₄ ^2? , and M² = OH^?) crystal-chemical family. Uranium-containing layers are linked into a three-dimensional framework via electrostatic interactions with outer-sphere cations and hydrogen bonds with water molecules.     

Two crystalline modifications of Pd<Subscript>2</Subscript>(μ-ac)<Subscript>2</Subscript>(acac)<Subscript>2</Subscript>

Crystal structures of two modifications of a binuclear Pd₂(μ-ac)₂(acac)₂ complex are studied at 150 K and 297 K (ac = acetate; acac = acetylacetonate). It is demonstrated that in both cases, the packing of the complexes can be considered as pseudohexagonal, the molecules forming infinite chains by interactions between chelate rings with the shortest contacts Pd...C _γ ～ 3.3 Å.     

Thermodynamic properties and molar heat capacity of Er<Subscript>2</Subscript>(Asp)<Subscript>2</Subscript>(Im)<Subscript>8</Subscript>(ClO<Subscript>4</Subscript>)<Subscript>6</Subscript>·10H<Subscript>2</Subscript>O

A complex of Erbium perchloric acid coordinated with l-aspartic acid and imidazole, Er₂(Asp)₂(Im)₈(ClO₄)₆·10H₂O was synthesized for the first time. It was characterized by IR and elements analysis. The heat capacity and thermodynamic properties of the complex were studied with an adiabatic calorimeter (AC) from 80 to 390 K and differential scanning calorimetry (DSC) from 100 to 300 K. Glass transition and phase transition were discovered at 220.45 and 246.15 K, respectively. The glass transition was interpreted as a freezing-in phenomenon of the reorientational motion of ClO⁴⁻ ions and the phase transition was attributed to the orientational order/disorder process of ClO⁴⁻ ions. The thermodynamic functions [H _T  − H _298.15] and [S _T  − S _298.15] were derived in the temperature range from 80 to 390 K with temperature interval of 5 K. Thermal decomposition behavior of the complex in nitrogen atmosphere was studied by thermogravimetric (TG) analysis and differential scanning calorimetry (DSC).     

Synthesis and crystal structure of Rb<Subscript>2</Subscript>[(UO<Subscript>2</Subscript>)<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(SeO<Subscript>4</Subscript>)] · 1.33H<Subscript>2</Subscript>O

The single crystals of Rb₂[(UO₂)₂(C₂O₄)₂(SeO₄)] · 1.33H₂O were synthesized and studied by X-ray diffraction. The crystals are monoclinic, space group P2₁/m, Z= 2, the unit cell parameters: a = 5.6537(8), b = 18.736(3), c = 9.4535(15) Å, β = 98.440(5)°, V = 990.6(3) ų, R ₁ = 0.0506. The main structural units of the crystal are infinite layers of [(UO₂)₂(C₂O₄)₂(SeO₄)]^2?, corresponding to the crystal chemical group A₂K ₂ ⁰² B² (A = UO ₂ ²⁺ , K⁰² = C₂O ₄ ^2? , B² = SeO ₄ ^2? ) of uranyl complexes. The uranium-containing layers are united into a three-dimensional framework through the electrostatic interactions with the outer-sphere rubidium ions and the hydrogen bonding system involving the outer-sphere water molecules.     

Lanthanide-Organic Frameworks Based on {Ln<Subscript>4</Subscript>(μ<Subscript>3</Subscript>-OH)<Subscript>4</Subscript>(μ<Subscript>2</Subscript>-OH)<Subscript>2</Subscript>} Cluster Units

Abstract  

Three novel lanthanide-organic frameworks: [Ln₂(pyba)₃(μ₃-OH)₂(μ₂-OH)(H₂O)] _n (Ln = Er (1), Y (2), Dy (3) Hpyba = 4-pyridin-4-yl-benzoic acid) have been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. Structure analysis shows that each {Ln₄(μ₃-OH)₄(μ₂-OH)₂} cluster units interconnect to form 1-D chains, which are further linked by π–π interactions to make a 3-D supramolecular network structure. Furthermore, the IR, PXRD and TGA of compounds 1–3 were also studied.     

Pyrazolate-bridged binuclear zinc complexes Zn<Subscript>2</Subscript>(μ-dmpz)<Subscript>2</Subscript>(Hdmpz)<Subscript>2</Subscript>(OOCR)<Subscript>2</Subscript> (R = Me,Ph; Hdmpz = 3,5-dimethylpyrazole)

Triethylamine reacts with aqueous zinc acetate and the product of its thermolysis in the presence of benzoic acid to yield the complexes [Zn₇(μ₄-O)(μ-OOCMe)₁₀][η-OC(Me)OHNEt₃]₂ (1) and [Zn₂(μOOCPh)₄][η-OC(Me)OHNEt₃]₂ (2), respectively. The reactions of 1 and 2 with 3,5-dimethylpyrazole at room temperature in benzene yield pyrazolate-bridged binuclear complexes Zn₂(μdmpz)₂(Hdmpz)₂(OOCR)₂ (R = Me (3), Ph (4)). The structures of complexes 1–4 have been determined by X-ray crystallography.     

Thermal stability of crandallite CaAl<Subscript>3</Subscript>(PO<Subscript>4</Subscript>)<Subscript>2</Subscript>(OH)<Subscript>5</Subscript>·(H<Subscript>2</Subscript>O)

Thermogravimetry combined with evolved gas mass spectrometry has been used to characterise the mineral crandallite CaAl₃(PO₄)₂(OH)₅·(H₂O) and to ascertain the thermal stability of this ‘cave’ mineral. X-ray diffraction proves the presence of the mineral and identifies the products of the thermal decomposition. The mineral crandallite is formed through the reaction of calcite with bat guano. Thermal analysis shows that the mineral starts to decompose through dehydration at low temperatures at around 139 °C and the dehydroxylation occurs over the temperature range 200–700 °C with loss of the OH units. The critical temperature for OH loss is around 416 °C and above this temperature the mineral structure is altered. Some minor loss of carbonate impurity occurs at 788 °C. This study shows the mineral is unstable above 139 °C. This temperature is well above the temperature in the caves of 15 °C maximum. A chemical reaction for the synthesis of crandallite is offered and the mechanism for the thermal decomposition is given.     

Crystal Structure of Neptunium(V) Acetate [(NpO<Subscript>2</Subscript>)<Subscript>2</Subscript>(OOCCH<Subscript>3</Subscript>)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)] ⋅ 2H<Subscript>2</Subscript>O

A new neptunium(V) complex [(NpO₂)₂(CH₃COO)₂(H₂O)] ? 2H₂O was synthesized and its crystal structure was determined. The unit cell parameters are: a = 24.007(10) Å, b = 6.779(3) Å, c = 8.076(3) Å, space group Pnma, Z = 4, V = 1314.2(9) ų, R = 0.049, wR(F²) = 0.105. The crystal structure of the compound is composed of neutral [(NpO₂)₂(CH₃COO)₂(H₂O)] layers and molecules of the water of crystallization. Each of the crystallographically independent neptunoyl ions performs a bidentate function thus forming a composite system of cation-cation bonds.     

Synthesis and structure of the complex [Mo<Subscript>3</Subscript>(μ<Subscript>3</Subscript>-S)(μ<Subscript>2</Subscript>-S<Subscript>2</Subscript>)<Subscript>3</Subscript>(Et<Subscript>2</Subscript>NCS<Subscript>2</Subscript>)<Subscript>3</Subscript>]I

The structure of tri-μ₂-disulfido-μ₃-thiotris(diethyldithiocarbamato)-S,S′-triangle-trimolybdenum iodide [Mo₃(μ₃-S)(μ₂-S₂)₃(Et₂NCS₂)₃]I was determined. The compound was characterized by differential thermal analysis and IR, Raman, and X-ray electronic spectroscopy.     

Magnetic properties of a linear trinuclear manganese compound [Mn<Subscript>3</Subscript>(PhCO<Subscript>2</Subscript>)<Subscript>6</Subscript>(Bipy)<Subscript>2</Subscript>] · H<Subscript>2</Subscript>O

The reaction of the trinuclear oxo-centered mixed-valence complex [Mn₃O(O₂CPh)₆(Py)₂(H₂O)] with 2,2′-bipyridyl (Bipy) and another potential tripodal ligand affords the title compound [Mn₃(PhCO₂)₆(Bipy)₂] · H₂O in good yield. The X-ray crystallographic diffraction study reveals that three mangenese ions are arranged in a linear mode with Mn_center-Mn_terminal and Mn_terminal-Mn_terminal diatances of 3.588 and 7.176 Å, respectively. Molar magnetic susceptibility of the compound gradually decreases from 12.23 (300 K) to 4.45 cm³ K mol^?1 (2 K). Taking into account the structure of this compound, the data in the 2.0–300 K range were fit to the appropriate theoretical expression to give J = ?2.73 cm^?1, ρ = 2.07%, N _a = ?0.0004 cm³ mol^?1, g = 1.992, and R ² = 0.99996. The magnetization versus external magnetic field measurements at 2 K shows that the ground state is S _T = 5/2.     

Neutron diffraction study of Rb<Subscript>2</Subscript>UO<Subscript>2</Subscript>(SeO<Subscript>4</Subscript>)<Subscript>2</Subscript> · 2D<Subscript>2</Subscript>O

A powder of deuterated rubidium diselenatouranylate dihydrate Rb₂UO₂(SeO₄)₂ · 2D₂O has been studied by neutron diffraction. The compound is orthorhombic, space group Pna2₁, with the following unit cell parameters: a = 13.654(2) Å, b = 11.863(2) Å, c = 7.625(1) Å, Z = 4, R _F = 3.77, R _I = 6.12, and χ² = 2.21. Basic structure units are [UO₂(SeO₄)₂ · D₂O]^2? layers belonging to the AB ₂ ² M¹ crystal-chemical group (A = UO ₂ ²⁺ , B² = SeO ₄ ^2? , M¹ = D₂O) of uranyl complexes. The hydrogen atoms if the water molecules involved in the layer form intralayer hydrogen bonds with the terminal oxygen atoms of selenate ions. The outer-sphere water molecules are coordinated to the rubidium ions and are involved in hydrogen bonding with oxygen atoms of neighboring [UO₂(SeO₄)₂ · D₂O]^2? layers.     

Synthesis,Structure and Solid-Phase Transformations of Fe Nitrosyl Complex Na<Subscript>2</Subscript>[Fe<Subscript>2</Subscript>(S<Subscript>2</Subscript>O<Subscript>3</Subscript>)<Subscript>2</Subscript>(NO)<Subscript>4</Subscript>] · 4H<Subscript>2</Subscript>O

Binuclear iron nitrosyl complex Na₂[Fe₂(S₂O₃)₂(NO)₄] · 4H₂O (I) was synthesized by the reaction of iron(II) sulfate with sodium thiosulfate in the flow of NO gas. According to X-ray diffraction data, the [Fe₂(S₂O₃)₂(NO)₄]^2– anion has binuclear centrosymmetric structure with Fe atoms bonded by the µ-S atoms of thiosulfate groups. The isomeric shift for complex I =0.168(1) mm/s and quadrupole splitting E _Q =1.288 mm/s at T=80 K. When heated, complex I transforms to Na₂[Fe₂(S₂O₃)₂(NO)₄] (II), whose unit cell parameters found by X-ray diffraction method differ from those of complex I. The process of transformation of I to II was studied by calorimetric method. Complex I transforms to complex II without chemical decomposition, which was confirmed by IR and mass spectroscopy data.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 323–328.Original Russian Text Copyright © 2005 by Sanina, Aldoshin, Rudneva, Golovina, Shilov, Shulga, Martynenko, Ovanesyan.     

Thermodynamic characteristics of europium pivalate binuclear complexes Eu<Subscript>2</Subscript>(Piv)<Subscript>6</Subscript> and [Eu<Subscript>2</Subscript>(Piv)<Subscript>6</Subscript> · (Phen)<Subscript>2</Subscript>]

Sublimation of europium pivalate binuclear complexes Eu₂(Piv)₆ and [Eu₂(Piv)₆ · (Phen)₂] (Piv = (CH₃)₃CCOO, Phen = C₁₂H₈N₂) in the temperature range of 383–660 K is studied by the Knudsen effusion method with mass-spectrometric analysis of the gas phase. The vaporization of Eu₂(Piv)₆ is shown to be accompanied by polymerization and the formation of Eu₂(Piv)₆ and Eu₄(Piv)₁₂ molecules. The saturated vapor over the mixed-ligand complex of europium pivalate with o-phenanthroline consists of Phen, Eu₂(Piv)₆, and Eu₄(Piv)₁₂ molecules. The partial pressures of the gas components, as well as the standard enthalpies of sublimation and dissociation of the reaction proceeding with removal of phenanthroline have been determined.     

Synthesis and X-ray diffraction study of Li(H<Subscript>3</Subscript>O)[UO<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)] · H<Subscript>2</Subscript>O

Single crystals of Li(H₃O)[UO₂(C₂O₄)₂(H₂O)] · H₂O (I) have been synthesized and studied by X-ray diffraction. Compound I crystallizes in the monoclinic crystal system with the unit cell parameters: a = 7.1682(10) Å, b = 29.639(6) Å, c = 6.6770(12) Å, β= 112.3(7)°, space group P 2₁/c, Z = 4, R = 4.36%. Structure I contains discrete mononuclear groups [UO₂(C₂O₄)₂(H₂O)]^2? ascribed to the crystal-chemical group AB ₂ ⁰¹ M¹ (A = UO₂ ²⁺, B⁰¹ =C₂O ₄ ^2? , M¹ = H₂O), which are “cross-linked” by the lithium ions into infinite layers {Li(UO₂)(C₂O₄)₂(H₂O)₂}^? perpendicular to [010]. The hydroxonium ions are located between adjacent uranium-containing layers. A hydrogen bond system involving water molecules, oxalate ions, and hydroxonium combines the anionic layers into a three-dimensional framework.     

Thermogravimetric analysis of wheatleyite Na<Subscript>2</Subscript>Cu<Superscript>2+</Superscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>·2H<Subscript>2</Subscript>O

Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates. These oxalates form as a film like deposit on rocks and other host matrices. The anhydrous oxalate mineral moolooite CuC₂O₄ as the natural copper(II) oxalate mineral is a classic example. Another example of a natural oxalate is the mineral wheatleyite Na₂Cu²⁺(C₂O₄)₂·2H₂O. High resolution thermogravimetry coupled to evolved gas mass spectrometry shows decomposition of wheatleyite at 255°C. Two higher temperature mass losses are observed at 324 and 349°C. Higher temperature mass losses are observed at 819, 833 and 857°C. These mass losses as confirmed by mass spectrometry are attributed to the decomposition of tennerite CuO. In comparison the thermal decomposition of moolooite takes place at 260°C. Evolved gas mass spectrometry for moolooite shows the gas lost at this temperature is carbon dioxide. No water evolution was observed, thus indicating the moolooite is the anhydrous copper(II) oxalate as compared to the synthetic compound which is the dihydrate.     

Synthesis and crystal structures of [K(H<Subscript>2</Subscript>O)(Piv)]<Subscript>∞</Subscript> and [K<Subscript>2</Subscript>(Phen)(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>(Piv)<Subscript>2</Subscript>]<Subscript>∞</Subscript>

A method for the synthesis of potassium pivalates (trimethylacetates) from potassium tert-butoxide and pivalic acid was proposed. The complexes of the formulas [K(H₂O)(Piv)]_∞(I) and [K₂(Phen)(H₂O)₂(Piv)₂]_∞ (II) (Piv denotes the pivalate anion and Phen denotes 1,10-phenanthroline) were obtained and characterized by elemental analysis and IR and ¹H NMR spectroscopy. The crystal structures of complexes I and II were determined using X-ray diffraction. Crystal structure I has a layered motif with two nonequivalent K atoms (C.N.s 5 + 2 and 6). The coordination of phenanthroline in II gives rise to a ribbon motif, the structure containing three nonequivalent K atoms (C.N.s 6, 6 + 1, and 8).     

Crystal structure of Na<Subscript>4</Subscript>[Na<Subscript>2</Subscript>Cr<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>6</Subscript>] · 10H<Subscript>2</Subscript>O

Single crystals of the Na₄[Na₂Cr₂(C₂O₄)₆] · 10H₂O complex were synthesized for the first time. The structure of the complex was determined by X-ray diffraction analysis. The compound crystallizes in the monoclinic crystal system with the unit cell parameters a = 17.290(4) Å, b = 12.521(3) Å, c = 15.149(3) Å, β = 100.45(3)°, Z = 4, space group Cc. Anionic layers [NaCr(C₂O₄)₃] _2n ^4n? can be distinguished in the crystal structure of the complex. The Na⁺ cations and water molecules, involved in the formation of a hydrogen bond network, are located between the anionic layers.     

High-temperature heat capacity of Pb<Subscript>8</Subscript>La<Subscript>2</Subscript>(GeO<Subscript>4</Subscript>)<Subscript>4</Subscript>(VO<Subscript>4</Subscript>)<Subscript>2</Subscript> in the range 320–1000 K

The oxide compound Pb₈La₂(GeO₄)₄(VO₄)₂ with an apatite structure has been synthesized by a ceramic method. The effect of temperature on the molar hear capacity of polycrystalline samples in the temperature range 320–1000 K has been studied by differential scanning calorimetry. The results have been used to calculate the thermodynamic functions of the synthesized compound.     

Balance,uniformity, and asymmetry of the structure of volborthite Cu<Subscript>3</Subscript>(OH)<Subscript>2</Subscript>(V<Subscript>2</Subscript>O<Subscript>7</Subscript>)·2H<Subscript>2</Subscript>O

Four structural models of volborthite Cu₃(OH)₂(V₂O₇)·2H₂O (a = 10.646(2) Å, b = 5.867(1) Å, c = 14.432(2) Å, β = 95.19(1)°, V = 897.7(5) ų, Z = 4, R/R _w = 0.038/0.046) calculated in the space groups determined from the systematic absences are compared. Based on the structure balance and the similarity of constituting polyhedra, values of the R factor, and isotropic thermal parameters, the space group Ia is found to be preferable, which is the only possible asymmetric and uniform variant. Hydrogen atoms of OH-groups, oxygen atoms and, partially, hydrogen atoms of water are localized.     

Crystal structure of Na<Subscript>3</Subscript>(NH<Subscript>4</Subscript>)<Subscript>2</Subscript>[Ir(SO<Subscript>3</Subscript>)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>]·4H<Subscript>2</Subscript>O

The complex Na₃(NH₄)₂[Ir(SO₃)₂Cl₄]·4H₂O was examined with single crystal X-ray diffraction and IR spectroscopy. Crystal data: a = 7.3144(4) Å, b = 10.0698(5) Å, c = 12.3748(6) Å, β = 106.203(1)°, V = 875.26(8) ų, space group P2₁/c, Z = 2, d _calc = 2.547 g/cm³. In the complex anion two trans SO ₃ ^2? groups are coordinated to iridium through the S atom. The splitting of O-H bending vibrations of crystallization water molecules and N-H ones of the ammonium cation is considered in the context of different types of interactions with the closest neighbors in the structure.