Phase equilibria in a ternary fullerenol-d(C<Subscript>60</Subscript>(OH)<Subscript>22–24</Subscript>)–SmCl<Subscript>3</Subscript>–H<Subscript>2</Subscript>O system at 25°C

The solubility in a ternary fullerenol-d (C₆₀(OH)_22–24)–SmCl₃–H₂O system at 25°C is studied via isothermal saturation in ampules. The solubility diagram is shown to be a simple eutonic one that consists of two branches corresponding to the crystallization of fullerenol-d (C₆₀(OH)_22–24 · 30H₂O) and samarium(III) chloride SmCl₃ · 6H₂O crystallohydrates and contains one nonvariant eutonic point corresponding to saturation with both crystallohydrates. The long branch of C₆₀(OH)_22–24 · 30H₂O crystallization shows the effect of fullerenol-d salting out of saturated solutions; in contrast, the short branch of SmCl₃ · 6H₂O crystallization shows the pronounced salting-in effect of samarium(III) chloride.     

Formation of Pd–Ag nanoparticles in supported catalysts based on the heterobimetallic complex PdAg<Subscript>2</Subscript>(OAc)<Subscript>4</Subscript>(HOAc)<Subscript>4</Subscript>

The formation of Pd–Ag nanoparticles deposited from the heterobimetallic acetate complex PdAg₂(OAc)₄(HOAc)₄ on α-Al₂O₃, γ-Al₂O₃, and MgAl₂O₄ has been investigated by high-resolution trans-mission electron microscopy, temperature-programmed reduction, and IR spectroscopy of adsorbed CO. The reduction of PdAg₂(OAc)₄(HOAc)₄ supported on γ-Al₂O₃ and MgAl₂O₄ takes place in two steps (at 15–245 and 290–550°C) and yields Pd–Ag particles whose average size is 6–7 nm. The reduction of the Pd–Ag catalyst supported on α-Al₂O₃ occurs in a much narrower temperature range (15–200°C) and yields larger nanoparticles (~10–20 nm). The formation of Pd–Ag alloy nanoparticles in all of the samples is demonstrated by IR spectroscopy of adsorbed CO, which indicates a marked weakening of the absorption band of the bridged form of adsorbed carbon monoxide and a >30-cm^–1 bathochromic shift of the linear adsorbed CO band. IR spectroscopic data for PdAg₂/α-Al₂O₃ suggest that Pd in this sample occurs as isolated atoms on the surface of bimetallic nanoparticles, as is indicated by the almost complete absence of bridged adsorbed CO bands and by a significant weakening of the Pd–CO bond relative to the same bond in the bimetallic samples based on γ-Al₂O₃ and MgAl₂O₄ and in the monometallic reference sample Pd/γ-Al₂O₃.     

Tautomeric and conformational properties of dibenzoylmethane,C<Subscript>6</Subscript>H<Subscript>5</Subscript>–C(O)–CH<Subscript>2</Subscript>–C(O)–C<Subscript>6</Subscript>H<Subscript>5</Subscript>: gas-phase electron diffraction and quantum chemical study

Tautomeric and structural properties of dibenzoylmethane, C₆H₅–C(O)–CH₂–C(O)–C₆H₅, have been investigated by gas-phase electron diffraction (GED) and quantum chemical calculations (B3LYP and MP2 approximation with different basis sets up to cc-pVTZ). Analysis of GED intensities resulted in the presence of 100(5)% enol tautomer at 380(5) K. The enol ring possesses C _S symmetry with a strongly asymmetric hydrogen bond. The two phenyl rings are rotated with respect to the enol ring by 15.1(5.0) and 12.1(5.8)°. The experimental geometric parameters are reproduced very closely by the B3LYP/cc-pVTZ method.     

π-Complex of Cu(I) Chloride with 1-Allyloxybenzotriazole CuCl · C<Subscript>6</Subscript>H<Subscript>4</Subscript>N<Subscript>3</Subscript>(OC<Subscript>3</Subscript>H<Subscript>5</Subscript>)

Single crystals of CuCl · C₆H₄N₃(OC₃H₅)(I) are synthesized by ac electrochemical method from Cu(II) chloride and 1-allyloxybenzotriazole in ethanol solution and their unit cell parameters are determined: space group P2₁/a a=11.583(4) , b=11.443(7) , c=8.620(4) , =108.77(3)°, V=1082(2) ³, R(F)=0.0366, R _w (F)=0.0396 for 1095 reflections. In the structure of -complex I, inorganic fragment Cu₂Cl₂ forms centrocymmetric parallelogram. A molecule of 1-allyloxybenzotriazole acts as a bridge, which is bonded to the Cu atoms of two inorganic dimers through the C=C bond of the allyl group and to the N atom of a triazole ring. Owing to this bridging function, the ligand molecules form zigzag organometallic layers. The trigonal-pyramidal coordination sphere of a metal atom includes two Cl atoms and the C=C group. The structural motif of complex I significantly differs from that of the previously studied 2CuCl · C₆H₄N₃(OC₃H₅) and resembles the motif of a bromide analog Cu₂Br₂ · [C₆H₄N₃(OC₃H₅)]₂.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 364–369.Original Russian Text Copyright © 2005 by Goreshnik, Myskiv.     

Clathrate [Zn(C<Subscript>6</Subscript>H<Subscript>5</Subscript>COO)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>] · 2CH<Subscript>3</Subscript>COOH: Synthesis and crystal structure

The clathrate [Zn(C₆H₅COO)₂(H₂O)₂] · 2CH₃COOH (I) was obtained for the first time from zinc(II) benzoate. The individuality, the unit cell parameters, and the number of “guest” molecules in complex I were determined from X-ray diffraction and derivatographic data. Its crystal structure was solved.     

Iridium–Ruthenium Cluster Complexes with SnPh<Subscript>3</Subscript> Ligands from the Reaction of IrRu<Subscript>3</Subscript>(CO)<Subscript>13</Subscript>(μ-H) with HSnPh<Subscript>3</Subscript>

The reaction of IrRu₃(CO)₁₃(μ-H), 1 with HSnPh₃ in hexane solvent at reflux has provided the new mixed metal cluster compounds Ir₂Ru₂(CO)₁₁(SnPh₃)(μ-H)₃, 2 and IrRu₃(CO)₁₁(SnPh₃)₃(μ-H)₄, 3 containing SnPh₃ ligands. Compound 2 which was obtained in low yield (3%) contains one SnPh₃, two iridium atoms and two ruthenium atoms. The increase in the number of iridium atoms must have resulted from a metal–metal exchange process. The major product 3 (19% yield) contains an open cluster of one iridium and three ruthenium atoms with three SnPh₃ ligands and four hydride ligands. Both compounds were characterized structurally by single crystal X-ray diffraction analysis.     

Crystal structure,infrared and raman spectra of tripotassium trisaccha-rinate dihydrate,K<Subscript>3</Subscript>(C<Subscript>7</Subscript>H<Subscript>4</Subscript>NO<Subscript>3</Subscript>S)<Subscript>3</Subscript>·2H<Subscript>2</Subscript>O

The crystal structure of tripotassium trisaccharinate dihydrate, K₃(C₇H₄NO₃S)₃·2H₂O, is triclic, space group\(P \bar 1, Z = 2\). It consists of three crystallographically independent potassium and saccharinato ions as well as two structurally different water molecules. Potassium coordination polyhedra are irregular, with K1 and K3 six-coordinated and the third one K2 seven-coordinated. The K?O distances range from 2.652(9) to 3.100(2) Å(mean: 2.790 Å) whereas the K?N distance is 3.025(3) Å. The water molecules W2 is disordered over three positions with occupancies of approximately 0.6, 0.2 and 0.2. The hydrogen atom (H1W1) of the ordered water molecule (O1W) is hydrogen bonded to the sulfonyl oxygen atom (O11) (R(O...O)=2.976(3) Å), whereas the other hydrogen atom (H2W1) is bifurcated to the carbonyl oxygen atom (O13) (R(O...O)=2.851(3) Å) and the disordered water molecules (O23W) (R(O...O)=3.067(12) Å). The carbonyl oxygens (O13, O23 and O33) and one of the disordered water molecules (O22W) are involved in C?H...O hydrogen bonds (R(C?H...O)=3.027(4)–3.304(9) Å). Structural characteristics of the studied compound are compared with the analogous trisodium trisaccharinate dihydrate and dipotassium sodium trisaccharinate monohydrate. Infrared and Raman spectra of the title compound have been analyzed in relation to the structure, and compared with the spectra of trisodium trisaccharinate dihydrate.     

Concentration Space of Homogeneous Garnet in the System Ga<Subscript>2</Subscript>O<Subscript>3</Subscript>–(Y,Bi)<Subscript>3</Subscript>(Fe,Ga)<Subscript>5</Subscript>O<Subscript>12</Subscript>–Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>

The concentration space of homogeneous garnet in the system Ga₂O₃–(Y, Bi)₃(Fe, Ga)₅O₁₂–Fe₂O₃ was determined by X-ray powder diffraction analysis. The obtained results expand the knowledge of the possible variations of cation ratios Y : Bi : Fe : Ga in garnet, which can be used for searching for and creating new stable magneto-optical materials.     

Phase transitions of K<Subscript>2</Subscript>TaF<Subscript>7</Subscript> within 680–800°C

Three thermal effects on heating/cooling of K₂TaF₇ in the temperature interval of 680–800°C were investigated by the DSC method. The values determined for the enthalpy change of the individual processes are: Δ_transIIH_m(K₂TaF₇; 703°C) = 1.7(2) kJ mol⁻¹, Δ_transIH_m(K₂TaF₇; 746°C) = 19(1) kJ mol⁻¹ and Δ_transIIIH_m(K₂TaF₇; 771°C) = 13(1) kJ mol⁻¹. The first thermal effect was attributed to a solid-solid phase transition; the second to the incongruent melting of K₂TaF₇ and the third to mixing of two liquids. These findings are supported by in situ neutron powder diffraction experiments performed in the temperature interval of 654–794°C.      

Heteronuclear alkali metal bis(μ-trihydroxyglutarato)dihydroxodigermanates(IV): The crystal and molecular structure of K<Subscript>4</Subscript>[Ge<Subscript>2</Subscript>(μ-Thgl)<Subscript>2</Subscript>(OH)<Subscript>2</Subscript>] · 4H<Subscript>2</Subscript>O

Heterometallic potassium and sodium trihydroxyglutaratogermanates of the formulas K₄[Ge₂(μ-Thgl)₂(OH)₂] · 4H₂O (I) and Na₄[Ge₂(μ-Thgl)₂(OH)₂] · 5H₂O (II) (H₅Thgl is trihydroxyglutaric acid) were obtained for the first time and characterized by elemental analysis, X-ray powder diffraction, thermogravimetry, and IR spectroscopy. Complex I was examined by single-crystal X-ray diffraction. The crystals are triclinic; a = 7.5933(15) Å, b = 7.628(4) Å, c = 10.516(4) Å, α = 104.01(3)°, β = 101.041(17)°, γ = 97.50(3)°, V = 570.0(3) ų, Z = 1, space group \(P\bar 1,R\bar 1 = 0.0479\) for 2848 reflections with I > 2σ (I). Complex I is made up of the centrosymmetric dimeric complex anions [Ge₂(μ-Thgl)₂(OH)₂]^4?, the potassium cations, and water molecules of crystallization. In the anion, the two Ge atoms are bridged by two fully deprotonated ligands Thgl^5?. The coordination polyhedron of the Ge(IV) atom is a distorted trigonal bipyramid. Its equatorial plane is made up of the O atom of the terminal OH group (Ge-O…OH, 1.760(2) Å) and the O atoms of two alcohol groups of two ligands Thgl^5? (av. Ge-O_alc, 1.797(2) Å; the angles O_eqGe(1)O_eq, 110.12°–137.11°). The axial positions are occupied by the O atom of the alcohol group (Ge-O_alc, 1.853(2) Å) and the carboxyl O atom of one carboxylate group (Ge-O_carb, 1.944(2) Å) of two symmetry-related ligands Thgl^5?. The angle O_axGeO_ax is 163.68(10)°. The second carboxylate group of the ligand Thgl^5? is not coordinated to the Ge atom. The coordination numbers of the cations K(1)⁺ and K(2)⁺ are seven and nine, respectively (K(1)-O, 2.685–2.889 Å; K(2)-O, 2.675–3.262 Å). In the crystal, the structural units are united into a three-dimensional framework.     

Temperature dependence of vibrational modes of CH3?CC(ads) and I(ads) coadsorbed on Ag(111): Ab initio molecular dynamics approach

Ab initio molecular dynamics simulations accompanied by a Fourier transform of the dipole moment (aligned perpendicular to the surface) autocorrelation function are implemented to investigate the temperature‐dependent infrared (IR) active vibrational modes of CH₃? C_(β)?C_(α)(ads) and I_(ads) when coadsorbed on an Ag(111) surface at 200 and 400 K, respectively. The analytic scheme of the Fourier transform of a structural coordinate autocorrelation function is used to identify two distinguishable IR active peaks of C_(β)?C_(α) stretching, which are characterized by two types of dynamic motion of adsorbed CH₃? C_(β)?C_(α)(ads) at 200 K, namely, the motion of the tilted ? C? C_(β)?C_(α)? axis and the motion of the stand‐up ? C? C_(β)?C_(α)? axis. These two recognisable IR active peaks of C_(β)?C_(α) stretching are gradually merged into one peak as a result of the dominant motion of the stand‐up ? C? C_(β)?C_(α)? axis as the temperature increases from 200 to 400 K. The calculated intensities of the IR active peaks of the asymmetrical deformation mode of CH₃ and the asymmetrical stretching mode of CH₃, with their dynamic dipole moments nearly perpendicular to the ? C? C_(β)?C_(α)? axis, become relatively weak; however, the symmetrical deformation mode of CH₃ and the symmetrical stretching mode of CH₃, with their dynamic dipole moments randomly directed away from the ? C? C_(β)?C_(α)? axis, will not have direct correspondence between the intensities of their IR active peaks and the angle between the Ag(111) surface and the ? C? C_(β)?C_(α)? axis as the temperature increases from 200 to 400 K. Finally, the increased flipping from the motion of the tilted ? C? C_(β)?C_(α)? axis to the motion of the stand‐up ? C? C_(β)?C_(α)? axis followed by its diffusion, resulting from the increasing temperature from 200 to 400 K or even higher, seems to be the initial event that initiates the alkyne self‐coupling reaction that leads to the final production of H₃C? C?C? C?C? CH₃. © 2012 Wiley Periodicals, Inc.     

Ternary Systems NaHal–NaVO<Subscript>3</Subscript>–Na<Subscript>2</Subscript>CrO<Subscript>4</Subscript> (Hal = Cl,Br)

Phase equilibria in the ternary systems NaHal–NaVO₃–Na₂CrO₄ (Hal = Cl, Br) were studied. By differential thermal analysis, eutectic alloys were found at points with coordinates (14.0 mol % NaCl, 66.5 mol % NaVO3, 19.5 mol % Na₂CrO₄, 530°C) and (27.0 mol % NaBr, 47.5 mol % NaVO₃, 25.5 mol % Na₂CrO₄, 499°C). By differential scanning calorimetry, the specific enthalpies of melting of the eutectics were determined. X-ray powder diffraction analysis of the eutectic alloy in the system NaBr–NaVO₃–Na₂CrO₄ was made.     

Synthesis and structure of a new molecular octahedral cluster complex Mo<Subscript>6</Subscript>Se<Subscript>8</Subscript>(Ph<Subscript>3</Subscript>P)<Subscript>6</Subscript>·2H<Subscript>2</Subscript>O

Mo₆Se₈(Ph₃P)₆·2H₂O cluster complex has been synthesized and its structure has been defined. The compound is triclinic, space group P1ˉ, with unit cell parameters a = 14.3356(5) Å, b = 15.7882(4) Å, c = 25.3949(8) Å, = 95.9750(10)°, β = 91.1030(10)°, γ= 112.2570(10)°, V = 5279.8(3) ų, Z = 2, ρ_calc = 1.772 g/cm³. The complex has a molecular structure. The molybdenum atoms of the {Mo₆Se₈} cluster nucleus are coordinated by the phosphorus atoms of triphenylphosphine molecules. Original Russian Text Copyright ? 2007 by Yu. V. Mironov, Zh. S. Kozhomuratova, D. Yu. Naumov, and V. E. Fedorov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 389–393, March–April, 2007.     

Synthesis,properties, and molecular and crystal structure of diantipyrylmethanium Bis(μ-tartrato)dihydroxydigermanate(IV) tetrahydrate (HDAm)<Subscript>2</Subscript>[Ge<Subscript>2</Subscript>(μ-L)<Subscript>2</Subscript>(OH)<Subscript>2</Subscript>] · 4H<Subscript>2</Subscript>O

The complex (HDam)₂[Ge₂(μ-L)₂(OH)₂] · 4H₂O (I) (H₄L is tartaric acid, Dam is diantipyrylmethane) was synthesized for the first time. The individual character and composition of I was established by elemental analysis and X-ray diffraction. The thermal stability of I was studied. The coordination sites of H₄L in the germanium complex were determined by IR spectroscopy. The structure of I was determined by X-ray crystallography. The crystals of I are triclinic: a = 9.3098(10) Å, b = 9.8088(10) Å, c = 17.6869(10) Å, α = 84.009(10)°, β = 77.926(10)°, γ = 67.088(5)°, V = 1454.3(2) ų, Z = 2, space group P \(\bar 1\), R = 0.0628 for 6343 reflections with I > 2σ(I). The compound is composed of the complex anions [Ge₂(μ-L)₂(OH)₂]^2?, the HDam⁺ cations, and crystal water molecules. In the dimeric anion, the metal atoms are bound to two completely deprotonated ligands L^4?. The latter are coordinated to the metal through the carboxyl (av. Ge-O, 1.911(6) Å) and hydroxyl (av. Ge-O, 1.768(6) Å) oxygen atoms. The coordination of each Ge atom is completed to trigonalbipyramidal by the O atom of the hydroxy ligand in the axial position (av. Ge-O, 1.748(7) Å). Both L^4? ligands are D isomers. In the crystal, the complex anions and crystal water molecules are combined by a system of hydrogen bonds.     

Crystal structure and solid–solid phase transition of the complex (C<Subscript>11</Subscript>H<Subscript>18</Subscript>NO)<Subscript>2</Subscript>CuCl<Subscript>4</Subscript>(s)

The complex (C₁₁H₁₈NO)₂CuCl₄(s) was synthesized. Chemical analysis, elemental analysis, and X-ray crystallography were used to characterize the structure and composition of the complex. Low-temperature heat-capacities of the compound were measured by an adiabatic calorimeter in the temperature range from 77 to 400 K. A phase transition of the compound took place in the region of 297–368 K. Experimental molar heat-capacities were fitted to two polynomial equations of heat-capacities as a function of the reduced temperature by least square method. The peak temperature, molar enthalpy, and entropy of phase transition of the compound were calculated to be T _trs = 354.214 ± 0.298 K, Δ_trs H _m = 76.327 ± 0.328 kJ mol⁻¹, and Δ_trs S _m = 51.340 ± 0.164 J K⁻¹ mol⁻¹.     

π-Complexes of Cu(I) with Alkynes. Synthesis and Crystal Structure of Cs[CuCl<Subscript>2</Subscript>(HOCH<Subscript>2</Subscript>C≡CCH<Subscript>2</Subscript>OH)] ⋅ H<Subscript>2</Subscript>O

Crystals of anionic π-complex Cs[CuCl₂(HOCH₂C≡CCH₂OH)] ? H₂O were synthesized by reaction of 2-butyne-1,4-diol with CuCl in a saturated aqueous solution of CsCl at 90°C and studied by X-ray diffraction analysis. The crystals are triclinic (space group \(P\bar 1\) ; a = 10.155(4) Å, b = 7.828(4) Å, c = 7.115(3) Å, α = 102.62(4)°, β = 100.77(3)°, γ = 106.71(4)°, V = 509(1) ų, Z = 2) and consist of stacks of individual anions [CuCl₂(HOCH₂C≡CCH₂OH)]^? and hydrated [Cs ? H₂O]⁺ cations between the stacks. The Cu(I) atom has trigonal surrounding of two Cl atoms and the C≡C bond of 2-butyne-1,4-diol molecule. The Cu-(C≡C) distance in the π-core is 1.905(8) Å; the C≡C bond is elongated to 1.223(11) Å. In addition to hydrogen bonds O-H?Cl, crystals of the complex also contain O(w)?H-O and O(w)?Cl bonds stabilizing their structure.     

The solubility of C<Subscript>70</Subscript> in <Emphasis Type="Italic">n</Emphasis>-alkanols-1 C<Subscript>1</Subscript>-C<Subscript>11</Subscript> over the temperature range 20–80°C

The isothermal (20°C) solubility of fullerene C₇₀ in solvents of the homologous series of nonbranched saturated alcohols C₁-C₁₁ and polythermal (20–80°C) solubility of fullerene C₇₀ in solvents of the homologous series of nonbranched saturated alcohols C₄-C₁₁ were studied. The corresponding solubility diagrams are presented and characterized.     

Reduction of nitrogen(I) oxide with carbon monoxide and C<Subscript>3</Subscript>–C<Subscript>4</Subscript> alkanes on Fe-containing zeolite catalysts

It is shown that in the presence of reducing agents — light alkanes (C₃–C₄) or carbon monoxide — the temperature for the elimination of nitrogen(I) oxide over iron-containing zeolite catalysts of various structural types (Y, M, pentasil) is reduced by 70–150 °C. In the presence of excess oxygen (SCR process conditions) a greater conversion of N₂O(90–94%) is achieved at even lower temperatures (up to 50–150 °C less) with the use of hydrocarbons, and the activity of the catalysts correlates with the presence of strongly acidic B centers on their surfaces.__________Translated from Teoreticheskaya i Éksperimentalnaya Khimiya, Vol. 41, No. 1, pp. 35–39, January–February, 2005.