Clathrate formation and phase equilibria in the thiourea-bromoform system

Phase equilibria in the thiourea (host)-bromoform (guest) binary system were studied by physicochemical analysis methods over the temperature range 270–455 K. The stoichiometry and stability region were determined for the channel-type compound CHBr₃ · 2.40(2)(NH₂)₂CS; the compound was observed for the first time. When heated, the clathrate incongruently decomposed at 424.0 ± 0.8 K to rhombic thiourea and the guest component. The solubility isotherm of the thiourea-bromoform-acetic acid system was studied to find that the compound was thermodynamically stable at 293 K over the range of guest component concentrations 100–35 wt %. A decrease in its content in an equilibrium mother liquor resulted in the appearance of X-ray diffraction reflections of the initial host α polymorph. Rhombohedral cell parameters were determined (space group R-3c, a = 15.89(1) Å, c = 12.40(1) Å, V = 2711(6) ų, d _calcd = 2.000 g/cm³, and d _expt = 1.98(2) g/cm³). The mode of packing of bromoform molecules was compared with the organization of the guest subsystem in inclusion compounds formed by the substances studied.     

Crystal structure of the 1:3 thiourea-hexachloroethane inclusion compound at 295 K

The crystal structure of the 1:3 thiourea-hexachloroethane inclusion compound at 295 K has been determined. The parameters of the rhombohedral Bravais cell (space group R3ˉc) are a = 16.097(2) Å, c = 12.450(3) Å, V = 2793.6(8) ų, d _calc = 1.659 g/cm³, d _exp = 1.661±0.005 g/cm³, Z = 6 for C₅H₁₂Cl₆N₆S₃. The disordered guest molecules lie in the channels (parallel to the c axis) of the clathrate framework constructed from thiourea molecules linked by N-H...S hydrogen bonds. The mutual arrangement of the carbon and chlorine atoms is such that they define four orientations of the C-C bond relative to the channel of the host framework with nearly eclipsed conformations of hexachloroethane: one orientation along the triple bond axis (channel axis) and three equiprobable orientations at an angle of 74(2)° to the axis; for the coaxial orientation, there are two different configurations of the guest with slightly different geometries. The relative contributions of each of the five orientations were determined from the site occupancies of the guest atoms: 26.18 (coaxial orientations) and 3×19%. The resulting structure model is compared with the literature data about guest disordering in the structure of an adduct of the same composition determined at 233 K and with other similar structures. Original Russian Text Copyright ? 2007 by S. F. Solodovnikov, G. N. Chekhova, G. V. Romanenko, N. V. Podberezskaya, Z. A. Solodovnikova, D. V. Pinakov, and A. R. Semenov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 348–357, March–April, 2007.     

Temperature-dependent selectivity of inclusion by <Emphasis Type="Italic">trans</Emphasis>-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid

From acetophenone solution with a small amount of water, a widely used clathrate forming compound, trans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid (DED), crystallizes either in the form of a clathrate with acetophenone (25°C) or in the form of hydrate (5°C). The clathrate of DED with acetophenone is triclinic, space group P-1 with the unit cell parameters: a = 8.5002(2) Å, b = 12.5247(8) Å, c = 12.8251(8) Å; α = 62.876(2)°, β = 80.454(2)°, γ = 89.789(2)°; V = 1194.4(1) ų, Z = 2; the molar ratio DED:acetophenone is 2:3. The clathrate is of channel type; the system of mutually intersecting channels propagates in [100] and [01–1] directions in the structure. The guest molecules of acetophenone are included in the channels and do not form any H-bonds with the host molecules of DED. The hydrate of DED crystallizes in monoclinic system, in space group C2/c, with the unit cell parameters: a = 31.770(6) Å, b = 8.503(2) Å, c = 12.888(3) Å; β = 104.26(3)°; V = 3374(1) ų, Z = 8; the molar ratio DED:water is 1:3. One of two carboxylic groups of the molecule of DED is deprotonated and the proton is incorporated into the hydroxonium ion H₃O⁺. The crystal structure of the hydrate of DED is of layer type with well distinguished hydrophobic and hydrophilic parts.     

Synthesis of spiro[(6-phenyl-3,4-dihydro-2H-1,3-dioxine)-2<Emphasis Type="Italic">R</Emphasis>(<Emphasis Type="Italic">S</Emphasis>), 3′-(19′,28′-oxidooleanan)]-4-ones and X-ray diffraction analysis of their configuration

The structure of two stereoisomeric spiroadducts of allobetulone with 5-phenyl-2,3-dihydrofuran-2,3-dione was established by X-ray diffraction (XRD) analysis. The crystals of the 2R isomer are orthorhombic, P2₁2₁2₁, a = 10.825(5) Å, b = 12.849(6) Å, c = 23.358(9) Å; V = 3249(2) ų, Z = 4, d _calc = 1.200 g/cm³; the crystals of the 2S isomer hemihydrate are triclinic, P1, a = 11.505(7) Å, b = 12.192(8) Å, c = 13.123(8) Å; α = 103.35(5)°, β = 100.80(5)°, γ = 90.98(5)°; V = 1756(2) ų, Z = 2, d _calc = 1.127 g/cm³. The molecular structure of the spiroadducts is discussed.     

Crystal structures of <Emphasis Type="Italic">trans</Emphasis>-[Re<Subscript>6</Subscript>S<Subscript>8</Subscript>(CN)<Subscript>2</Subscript>L<Subscript>4</Subscript>] complexes,L = pyridine or 4-methylpyridine

The structures of three novel octahedral rhenium cluster compounds [Re₆S₈(CN)₂(py)₄]·H₂O (1), [Re₆S₈(CN)₂(4-Mepy)₄] (2), [Re₆S₈(CN)₂(4-Mepy)₄]·4-Mepy (3) (py = pyridine, 4-Mepy = 4-methylpyridine) are determined by X-ray crystallography. Crystal data are: C2/m space group, a = 14.813(1) Å, b = 14.772(1) Å, c = 9.2122(6) Å, β = 119.085(2)°, V = 1761.7(2) ų, d _x = 3.318 g/cm³, R = 0.0585 (1); I4₁/amd space group, a = 16.0018(3) Å, c = 14.7186(5) Å, V = 3768.81(16) ų, d _x = 3.169 g/cm³, R = 0.0489 (2); P2₁/c space group, a = 9.0452(4) Å, b = 15.8065(7) Å, c = 15.2951(6) Å, β = 103.700(2)°, V = 2124.57(16) ų, d _x = 2.957 g/cm³, R = 0.0245 (3). Molecular cluster complexes interact via π-π stacking affording 3D frameworks in 1 and 2 and chains in 3.     

Crystal structure of KPb<Subscript>2</Subscript>Cl<Subscript>5</Subscript> and KPb<Subscript>2</Subscript>Br<Subscript>5</Subscript>

The KPb₂Cl₅ and KPb₂Br₅ crystals are monoclinic (P2₁/c) with a microtwinned structure. X-ray analysis of chloride resulted in the parameters a = 8.854(2) Å, b = 7.927(2) Å, c = 12.485(3) Å; β = 90.05(3)°, d_calc = 4.78(1) g/cm³ (STOE STADI4, MoK_α, 2θ_max = 80°), R₁ = 0.0702 for 4094 F ≥ 4 σ(F) reflections. For bromide, a = 9.256(2) Å, b = 8.365(2) Å, c = 13.025(3) Å; β = 90.00(3)°, d_calc = 5.62(1) g/cm³ (Bruker P4, MoK_α, 2θ_max = 70°), R₁ = 0.0692 for 3076 F ≥ 4 (F) reflections.     

Synthesis,structure, and properties of the thermolysis products of [Os(NH<Subscript>3</Subscript>)<Subscript>5</Subscript>Cl][ReCl<Subscript>6</Subscript>]

The crystal structure of [Os(NH₃)₅Cl][ReCl₆] has been refined by X-ray powder analysis: a = 11.645(3) Å, b = 8.3788(2) Å, c = 15.277(4) Å, β = 91.029(6)°, V = 1490(1) ų, d _x = 3.163 g/cm³, space group P2₁/m, Z = 4. The thermolysis product of the salt in a hydrogen atmosphere is a solid substitution solution Os_0.5Re_0.5: a = 2.753(2) Å, c = 4.366(3) Å, space group P6₃/mmc; coherent scattering region (CSR) is ～230 Å.     

Chromites YbMCr<Subscript>2</Subscript>O<Subscript>5</Subscript> (M = Li,Na, K,Cs): X-ray diffraction study

Ytterbium alkali-metal chromites YbMCr₂O₅ (M = Li, Na, K, Cs) were synthesized by a ceramic procedure from the corresponding oxides and carbonates. Their crystal systems and unit cell parameters were determined by the homology method: for YbLiCr₂O₅, a = 10.34 Å, b = 10.62 Å, c = 15.05 Å, Z = 16, V ^o = 1653.74 ų, ρ_X-ray = 5.85 g/cm³, ρ_pycn = 5.81 ± 0.03 g/cm³; for YbNaCr₂O₅, a = 10.30 Å, b = 10.56 Å, c = 16.46 Å, Z = 16, V ^o = 1790.32 ų, ρ_X-ray = 5.64 g/cm³, ρ_pycn = 5.59 ± 0.07 g/cm³; for YbKCr₂O₅, a = 10.33 Å, b = 10.63 Å, c = 19.93 Å, Z = 16, V ^o = 2188.47 ų, ρ_X-ray = 5.95 g/cm³, ρ_pycn = 5.91 ± 0.03 g/cm³; and for YbCsCr₂O₅, a = 10.34 Å, b = 10.63 Å, c = 18.43 Å, Z = 16, V ^o = 2025.72 ų, ρ_X-ray = 5.19 g/cm³, ρ_pycn = 5.16 ± 0.05 g/cm³.     

Synthesis and X-ray investigation of Rb<Subscript>2</Subscript>[Pd(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>] and Cs<Subscript>2</Subscript>[Pd(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>]

Powder and single crystal X-ray diffraction studies have been performed for anhydrous nitrate complexes Rb₂[Pd(NO₃)₄] (I) and Cs₂[Pd(NO₃)₄] (II). Crystal data for I: a = 7.843(1) Å, b = 7.970(1) Å, c = 9.725(1) Å; β = 100.39(1)°, V = 597.9(1) Å ³, space group P2₁/c, Z = 2, d _calc = 2.918 g/cm³; for II: a = 10.309(2) Å, b = 10.426(2) Å, c = 11.839(2) Å; β = 108.17(3)°, V = 1209.0(4) ų, space group P2₁/c, Z = 4, d ^calc = 3.408 g/cm³. The structures are formed by isolated [Pd(NO₃)₄]^2? complex anions and alkali metal cations. The plane-square environment of the Pd atom is formed from the oxygen atoms of the monodentate nitrate groups. The geometrical characteristics of the complex anions are analyzed. Compound II has a short contact Pd...Cs 3.252 Å.     

X-ray structural study of fluorinated β-diketonate complexes of zirconium(IV)

Three novel complexes of zirconium(IV) are prepared and characterized by single crystal X-ray diffraction: zirconium(IV) pivaloyltrifluoroacetonate Zr(ptac)₄, zirconium(IV) trifluoroacetylacetonate Zr(tfac)₄, and zirconium(IV) hexafluoroacetylacetonate Zr(hfac)₄. Crystal data for C₃₂H₄₀F₁₂ZrO₈: a = 19.9842(6) Å, b = 11.8417(3) Å, c = 16.4831(5) Å; β = 95.2880(10)°, monoclinic, space group Cc, Z = 4, d _calc = 1.491 g/cm³, R = 0.061. Crystal data for C₂₀H₁₆F₁₂ZrO₈: a = 21.5063(15) Å, b = 7.9511(5) Å, c = 16.0510(10) Å; β = 113.736(4)°, monoclinic, space group C2/c, Z = 4, d _calc = 1.860 g/cm³, R = 0.047. Crystal data for C₂₀H₄F₂₄ZrO₈: a = 15.3533(13) Å, b = 20.2613(15) Å, c = 19.6984(17) Å; β = 95.828(2)°, monoclinic, space group P2₁/c, Z = 2, d _calc = 2.004 g/cm³, R = 0.078. All the structures are molecular and include isolated mononuclear Zr(β-dik)₄ complex molecules. Coordination environment of zirconium atom is made by eight oxygen atoms of four β-diketonates; the coordination polyhedron is an almost regular square antiprism. The Zr-O distances fall within 2.14–2.23 Å. Complexes in the structures are joined by van der Waals interactions. Using the structural data, the van der Waals energies of crystal lattices of the studied compounds are calculated by the atom-atom potential method.     

Structural investigation of [Au(en)<Subscript>2</Subscript>]Cl(ReO<Subscript>4</Subscript>)<Subscript>2</Subscript> and [Au(en)<Subscript>2</Subscript>](ReO<Subscript>4</Subscript>)<Subscript>3</Subscript> complexes

Novel complex salts [Au(en)₂]Cl(ReO₄)₂ (I) and [Au(en)₂](ReO₄)₃ (II), en = ethylenediamine, are obtained. Their crystal structures are determined by single crystal X-ray diffraction. Complex I crystallizes in the triclinic crystal system: a = 6.2172(7) Å, b = 7.1644(8) Å, c = 8.8829(8) Å, α = 96.605(4)°, β = 110.000(4)°, γ = 97.802(4)°, P-1 space group, Z = 1, d _x = 3.905 g/cm³; complex II crystallizes in the monoclinic crystal system: a = 15.244(2) Å, b = 7.6809(8) Å, c = 9.3476(12) Å, β = 127.004(3)°, C2 space group, Z = 4, d _x = 4.057 g/cm³.     

Synthesis and structural investigation of hafnium(IV) complexes with acetylacetone and trifluoroacetylacetone

Two volatile hafnium(IV) complexes with acetylacetone and trifluoroacetylacetone (HL) have been prepared and their structures have been studied at ?30°C. Crystal data for C₂₀H₂₈HfO₈: a = 21.5493(4) Å, b = 8.36720(10) Å, c = 13.9905(3) Å; β = 116.5550(10)°, space group C2/c, Z = 4, d _calc = 1.692 g/cm³, R = 0.015. Crystal data for C₂₀H₁₆F₁₂HfO₈: a = 8.1039(12) Å, b = 11.4499(14) Å, c = 15.790(2) Å; α = 99.341(4)°, β = 103.175(4)°, γ = 108.185(4)°, space group P?1, Z = 2, d _calc = 2.003 g/cm³, R = 0.074. Both structures are molecular and comprise isolated complex molecules HfL₄. The hafnium atom is coordinated with eight oxygen atoms of four β-diketonate ligands, Hf-O distances varying from 2.153 Å to 2.191 Å. The molecules make van der Waals contacts in the structures.     

Crystal structures of rhodium(III) aqua ion with tetrahedral anions

The crystal structures of compounds of the composition [Rh(H₂O)₆]₂(SO₄)₃·5H₂O (I) and [Rh(H₂O)₆]PO₄ (II) are determined. Crystallographic data for I: a = 7.272(9) Å, b = 27.047(1) Å, c = 12.464(9) Å, β = 97.038(10)°, P2₁ space group, Z = 4, d _x = 2.184 g/cm³; for II: a = 9.746(6)Å, b = 6.877(7) Å, c = 23.623(6) Å, β = 100.601(10)°, C2/c space group, Z = 8, d _x = 2.611 g/cm³. Compounds are analyzed by IR spectroscopy and powder XRD. Crystalline phase I is well soluble in water, whereas II is almost insoluble.     

Crystal structures of <Emphasis Type="Italic">trans</Emphasis>-dichlorobis(ethylendiamine) rhodium(III) with univalent anions

The crystal structures of the compounds trans-[Rh(en)₂Cl₂]Cl₂ · H₅O₂ (I), trans-[Rh(en)₂Cl₂]ClO₄ (II), and trans-[Rh(en)₂Cl₂]ReO₄ (III) are determined. The crystal data are: I, a = 10.860(3) Å, b = 7.795(2) Å, c = 9.023(3) Å; β = 111.56(10)°, P2₁/c space group, Z = 4, d _x = 1.875 g/cm³; II, a = 6.593(2) Å, b = 8.309(3) Å, c = 11.922(4) Å, α = 83.55(10)°, β = 79.80(10)°, γ = 75.38(10)°, P \(\bar 1\) space group, Z = 2, d _x = 2.106 g/cm³; III, a = 6.533(2) Å, b = 16.391(4) Å, c = 12.411(3) Å; β = 98.30(10)°, P2₁/c space group, Z = 4, d _x = 2.749 g/cm³. The compounds are examined by IR spectroscopy and powder XRD. The solubility of the isolated crystalline phases in water decreases in the following order: trans-[Rh(en)₂Cl₂]Cl₂·H₅O₂ > trans-[Rh(en)₂Cl₂]ClO₄ > trans-[Rh(en)₂Cl₂]ReO₄.     

Structure and properties of the volatile isomers of bis(1,1,1-trifluoro-5,5-dimethylhexane-2,4-dionato) of platinum(II)

In the work, isomeric complexes of platinum(II) with the (ptac)^–1 pivaloyltrifluoroacetonate ion (Pt((CH₃)₃–CO–CH–CO–CF₃)₂) are studied. The synthesis and chromatographic separation of Pt(ptac)₂ isomers are described, TGA data for the separated isomers are given, and the crystal structures of the solid phases are studied. The cis-Pt(ptac)₂ complex crystallizes in the space group P-1, a = 10.7091(4) Å, b = 12.7787(6) Å, c = 16.0154(8) Å, α = 92.389(2)°, β = 90.868(2)°, γ = 112.1260(10)°, V = 2027.39(16) ų, Z = 4, d _calc = 1.918 g/cm³. The trans-Pt(ptac)₂ complex crystallizes in the space group C2/m, a = 13.3235(5) Å, b = 8.5515(3) Å, c = 9.6694(3) Å, β = 118.5880(10)°, V = 967.38(6) Å3, Z = 2, d _calc = 2.010 g/cm3. The structures of the complexes are molecular, the Pt atom has a square coordination of four oxygen atoms of two ligands; for cis-Pt(ptac)2, the Pt–Oav distance is 1.968 Å, for trans-Pt(ptac)2 it is 1.980 Å.     

Crystallochemical study of ruthenium(III) tris-dipivaloylmethanate

The structure of ruthenium(III) dipivaloylmethanate is determined by single crystal X-ray diffraction at temperature of 150 K. The crystallographic data for C₃₃H₅₇O₆Ru are as follows: a = 9.6119(11) Å, b = 17.4603(19) Å, c = 21.519(2) Å, β = 95.187(2)°, C2/c space group, V = 3596.7(7) ų, Z = 4, d_calc = = 1.202 g/cm³, R = 0.0642. The structure is molecular, the metal atom coordinates six oxygen atoms of three ligands of β-diketone. The Ru–O distances are in the range of 1.99 Å to2.03 Å. The complexes have a distorted single layer hexagonal packing with the Ru…Ru distances being 9.84 Å within the layer, and 10.93 Å between the layers.     

Synthesis and X-ray diffraction study of ferrites ErM<Superscript>I</Superscript>Fe<Subscript>2</Subscript>O<Subscript>5</Subscript> (M<Superscript>I</Superscript> = Li,Na, K,Cs)

Ferrites of composition ErM^IFe₂O₅ (M^I = Li, Na, K, Cs) were synthesized by a solid-phase method. The structure of the ferrites was for the first time studied by X-ray powder diffraction. Crystal systems, unit cell parameters, and X-ray and pycnometric densities were determined. For ErLiFe₂O₅, a = 10.510 Å, c = 14.270 Å, V°= 1616.16 ų, Z = 16, V _subcell ^° = 101.01 ų, ρ_x = 6.01 g/cm³, ρ_pyc = 5.97 ± 0.04 g/cm³; for ErNaFe₂O₅, a = 10.519 Å, c = 15.510 Å, V° = 1759.56 ų, Z = 16, V _subcell ^° = 109.90 ų, ρ_x = 5.77 g/cm³, ρ_pyc = 5.72 ± 0.08 g/cm³; for ErKFe₂O₅, a = 11.050 Å, c = 15.480 Å, V° = 1937.33 ų, Z = 16, V _subcell ^° = 121.08 ų, ρ_x = 5.46 g/cm³, ρ_pyc = 5.41 ± 0.04 g/cm³; and for ErCsFe₂O₅, a = 10.78 Å, c = 16.01 Å, V° = 1905.37 ų, Z = 16, V _subcell ^° = 119.09 ų, ρ_x = 6.86 g/cm³, ρ_pyc = 6.61 ± 0.01 g/cm³.     

Structure and thermal properties of double complex salts [RuNO(NH<Subscript>3</Subscript>)<Subscript>4</Subscript>(H<Subscript>2</Subscript>O)]<Subscript>2</Subscript>[MCl<Subscript>4</Subscript>]Cl<Subscript>4</Subscript>·2H<Subscript>2</Subscript>O,M = Pt,Pd

Double complex salts (DCS) [RuNO(NH₃)₄(H₂O)]₂[MCl₄]Cl₄·2H₂O, M = Pt (I) and Pd (II), are prepared and characterized using IR spectroscopy, single crystal and powder X-ray diffraction, and thermogravimetric analysis. Crystalline phases of I and II are isostructural (P2(1)/n space group) and have the following crystallographic characteristics: a = 6.689 Å, b = 15.609 Å, c = 12.348 Å, V = 1289.1 ų, Z = 2, d _x = 2.425 g/cm³ (I) and a = 6.637 Å, b = 15.521 Å, c = 12.244 Å, V = 1261.2 ų, Z = 2, d _x = 2.255 g/cm³ (II). The thermolysis of the obtained DCS in the hydrogen atmosphere affords two-phase mixtures of limited solid solutions of the metals: hcp for ruthenium-based ones and fcc for Pt or Pd based solutions. On decomposition in the helium atmosphere the products contain a minor amount of RuO₂. For the phases obtained during thermolysis the parameters are determined and the compositions are estimated. The heating of I to 400°C in the helium-air atmosphere yields a nanocrystalline composite Pt+RuO₂ with CSR of ～20 nm.     

Investigation of pentaamminechloroplatinum(IV) perrhenate dihydrate

The crystal structure of the [Pt(NH₃)₅Cl](ReO₄)₃·2H₂O salt is determined. Crystallographic data: a = 10.3476(2) Å, b = 12.8955(2) Å, c = 14.3536(3) Å, β = 105.241(10)°, V = 1847.94(6) ų, space group P ₂1/n, Z = 4, d _x = 3.962 g/cm³. Thermal decomposition of the compound is studied in a helium and hydrogen atmosphere. A two-phase product arises in the former case, in the latter a substitution Re_0.75Pt_0.25 solid solution with unit cell parameters: a = 2.767(2) Å, c = 4.441(3) Å, space group P6₃/mmc.     

Structure of A Coordination Polymer [Cu(En)<Subscript>2</Subscript>CrO<Subscript>4</Subscript>]<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>

The crystal structure of [Cu(En)₂CrO₄]_n (En is ethylenediamine) is determined: a = 14.7359(4) Å, b = 9.8083(3) Å, c = 14.2664(4) Å, V = 2061.98(10) ų, space group Cmce, Z = 8, d_x = 1.931 g/cm³. It is demonstrated that the studied phase is isostructural with [Сu(Еn)₂SO₄]_n. A pseudotetragonal copper atom coordination (Cu–N 2.0204 Å and 2.0244 Å, ∠N–Cu–N 84.73°) is completed to distorted octahedral by two oxygen atoms of chromate anions (Cu–O 2.433 Å and 2.380 Å).