Phase formation in the Dy2O3-HfO2-MoO3 system. Crystal structure of the new binary molybdate Dy2Hf2(MoO4)7

Phase relations have been studied for the subsolidus region of the Dy₂O₃-HfO₂-MoO₃ system; binary molybdates, Dy₂Hf(MoO₄)₅ and Dy₂Hf₂(MoO₄)₇, were found to form. The crystal structure of the latter has been solved (a = 20.661(3) , b = 9.816(1) , c = 13.796(3) , = 113.47(1)°, Z = 4, space group C2/c, R = 0.023) and found to be a new type of structure. In the structure, MoO₄ tetrahedra are linked by their vertices with HfO₆ octahedra and DyO₈ tetragonal antiprisms to form a 3D open-work, in which one can isolate double-row tetrahedral and octahedral chains extended down the c axis.Original Russian Text Copyright © 2004 by S. F. Solodovnikov, B. G. Bazarov, E. Yu. Badmaeva, Yu. L. Tushinova, E. S. Zolotova, and Zh. G. BazarovaTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 692–697, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Configurations of the [Pd(NO2)4]2- Complex Anion: Crystal Structure of Ag4A2[M(NO2)4]3 (M = Pd, Pt; A = K, Rb)

An integrated Xray diffraction study was performed on polycrystals and single crystals of three new isostructural phases with general formula Ag₄A₂[M(NO₂)₄]₃ (M = Pd, Pt; A = K, Rb). Data on the crystal structure solution (CAD4 diffractometer, MoK radiation, graphite monochromator = 2–30° are presented. In one crystallographically independent [M(NO₂)₄]^2- complex anion, the planar square coordination of the central atom is completed to 4 + 2 by two oxygen atoms at a distance of 3.02–3.12 in the other anion, it is completed to 4 + 1 + 1 by an oxygen atom at a distance of 3.12–3.30 and an Ag⁺ cation at a distance of 3.04–3.11 . Part of the Ag⁺ cations form Ag - Ag dimers with a distance of 3.03–3.07. Crystalchemical analysis of known structures containing [Pd(NO₂)₄]^2- complex anions was performed. It has been established that in none of the cases do any of the possible limiting configurations occur.     

Di- and tri-nuclear osmium carbonyl chloride complexes: x-ray structures of Os2(CO)8Cl2 and Os3(CO)12Cl2

Summary Os₂(CO)₈Cl₂ (1) is orthorhombic P2₁2₁2₁ witha=9.3599(9),b=9.879(2),c=16.014(3), V=1480³, D_c=3.03 Mgm^–3 for Z=4. Structure solved by Patterson methods. Final R=0.038, R_w=0.038 [w=(²F)] for 1270 observed reflections and 141 parameters. Os₃(CO)₁₂Cl₂ (2) is monoclinic C2/m witha=12.105(3), b=10.612(3),c=8.798(1) , =117.02(2)°, V=1006³, D_c=3.22 Mgm^–3 for Z=2. Structure solved by Patterson methods. Final R=0.036, R_w=0.037 (w=(²F)^–) for 821 observed reflections and 75 parameters.Complex(1) has an osmium-osmium single bond 2.897(1), with the chloride ligands in equatorial positions,(2) has a linear triosmium chain with osmium-osmium single bonds 2.893(1) and the chloride ligands occupy equatorial sites on the terminal osmium atoms. Both(1) and(2) are isostructural with their osmium carbonyl iodide analogues.     

Crystal and molecular structure of trans-diiodobis-(1-methyl-5-nitroimidazole)platinum(II)

Summary A new platinum complex of 1-methyl-5-nitroimidazole has been obtained and characterized by elemental analysis, i.r. and n.m.r. spectroscopy. The structure of [PtI₂-(C₄ H₅N₃O₂)₂] has been determined by single-crystal X-ray diffraction. The crystals are triclinic: P1, a = 15.640(3), b = 12.617(2), c = 6.701(1) , = 102.77(5), = 101.15(5), = 100.71(5)°, V = 1228.6(3) ³, Z = 3, D_x = 2.851(6) Mg m^–3, (MoK ) = 0.71069 , = 12.85 mm^–, F(000) = 948, final R = 0.038 for 2859 reflections. The complex consists of monomeric PtI₂(1-methyl-5-nitroimidazole)₂ units. The coordination geometry is square-planar. The two 1-methyl-5-nitroimidazole ligands are trans coordinated to platinum.     

Synthesis, Structure, and Thermal Decomposition of Chloropentamminerhodium(III) Hexabromoplatinate(IV)

The binary complex salt [Rh(NH₃)₅Cl][PtBr₆] was synthesized and studied by Xray structural analysis. The crystallographic data are as follows: a = 12.013(2) , b = 8.401(2) , c = 15.999(3) , = 91.13(3)°, V = 1614.3(6) ³, space group P2₁/m, Z = 4, d_x = 3.70 g/cm³, R = 0.086. The thermal decomposition of the salt in a hydrogen atmosphere is shown to produce a Rh_0.5Pt_0.5 solid solution with an FCC cell [a = 3.864(2) . The thermal decomposition of the salt in a helium atmosphere proceeds via the formation of metallic Pt and RhBr₃ and finally results in a mixture of several solid solutions.     

Crystal and Molecular Structure of Platinum(II) trans-Bis-(1,1,1-trifluoro-4-iminopentan-2-onate)

This paper describes a new method for the synthesis of the -iminoketonate complex Pt(ktf)₂ using 1,1,1-trifluoro-4-iminopentan-2-one as a bidentate ligand. An X-ray study has been performed on the polycrystals and single crystals of the compound. The single crystal X-ray diffraction analysis was carried out on a CAD-4 diffractometer (MoK radiation, /2 scan mode). Crystal data: a = 10.217(2), b = 10.231(2), c = 10.924(2) , = 83.12(3), = 63.38(3), = 70.77(3)°, V = 963.4(3) ³, space group P1, Z = 2, d _calc = 1.721 g/cm³. The Pt atom has a distorted planar square environment; the average lengths of Pt–N and Pt–O coordination bonds coincide (1.97 ). The mean value of the chelate angle is 94.2°. The environment of Pt is completed to bipyramid by the hydrogen atoms of the neighboring molecules. The structure of the compound is molecular. The differently oriented molecules of the complex are linked into chains down the x axis with Pt...Pt distances of 5.10 . A comparative crystal-chemical analysis of the structures of Pt(ktf)₂ and Pd(ktf)₂ and their O,O-chelate analogs — Pt(II) and Pd(II) trifluoroacetylacetonates — has been carried out. An X-ray study of Pt(tfa)₂ and Pd(tfa)₂ has been accomplished, and crystal data are given.     

Novel chromium trinuclear trifluoroacetate complexes Cr3(μ3-O)(CF3COO)6(CH3COOH)2(CF3COO) and Cr3(μ3-O)(CF3COO)6(CH3COOH)2(THF): Synthesis and crystal structure

Novel anhydrous trinuclear ₃-oxo complexes of Cr(III), Cr₃(₃-O)(CF₃COO)₆(CH₃COOH)₂(CF₃COO) (I) and of Cr(III,III,II), Cr₃(₃-O)(CF₃COO)₆(CH₃COOH)₂(THF) (II) (where THF is (CH₂)₄O) are synthesized by anodic dissolution of metallic chromium in solutions of trifluoroacetic acid in acetonitrile and in tetrahydrofuran and their structures are studied by X-ray diffraction analysis. Complex I forms orthorhombic crystals with space group Pna2₁, a = 9.778(1) , b = 16.042(2) , c = 22.851(4) , Z = 4, R ₁ = 0.0332; complex II crystallizes in monoclinic system: space group P2₁/c, a = 9.866(1) , b = 17.895(2) , c = 21.167(4) , = 100.75(2)°, Z = 4, R = 0.0422. The average Cr-(₃-O) distances in compounds I and II are almost equal (1.943(3) and 1.927(3) ). An average length of the Cr-O bond in octahedral surrounding of metal atoms is different in complexes I and II (1.985(4) and 2.003(3) , respectively), which is specified by different oxidation states of the metal atom. The CrCr distances lie in an interval of 3.366(1)–3.337(1) .__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 4, 2005, pp. 266–272.Original Russian Text Copyright © 2005 by Glazunova, Boltalin, Troyanov.     

Two Modifications of the Mixed-Ligand Complex ZnPhen(i-C3H7OCS2)2 with Monodentate and Bidentate Ligands i-C3H7OCS 2 -

Two crystal modifications (m-1 and m-2) of the mixed-ligand complex ZnPhen(i-PrOCS₂)₂ have been isolated. Their crystal structures were solved using X-ray diffraction data (CAD-4 diffractometer, MoK radiation, 3141 and 3532 F_hkl, R = 0.0363 and 0.0304). For both modifications, the crystals are monoclinic with unit cell parameters a = 10.543(2), b = 13.494(3), c = 16.875(3) , = 102.08(3)°, V = 2347.6(8) ³, Z = 4, space group P2₁/n (m-1) and a = 10.931(2), b = 12.996(3), c = 16.288(3) , = 92.69(3)°, V = 2311.3(8) ³, Z = 4, space group P2₁/n (m-2). The structures basically consist of discrete monomer molecules in which the Zn atom has a tetragonal pyramidal (m-1: ZnN₂S₃, c.n. 5, bidentate and monodentate i-PrOCS ₂ ^- ligands) or distorted octahedral (m-2: ZnN₂S₄, c.n. 6, bidentate i-PrOCS ₂ ^- ligands) environment. Molecular packings and their interactions in the structures are discussed.     

Crystal and Molecular Structure of Cu(II) Bis-(2-methoxy-2,6-dimethyl-3-imino-5-heptanonate)

A new compound from the series of alkoxyketoiminates, Cu(II) bis-(2-methoxy-2,6-dimethyl-3-imino-5-heptanonate), has been synthesized and studied by X-ray crystallography. Crystal data for CuO₄N₂C₂₀H₃₆: a=10.154(1), b=9.921(1), c=11.684(2) , =96.17(1)°, space group P2₁/c, Z=2, dcalc =1.226 g/cm³, R=0.037. The structure is molecular and built from isolated trans-complexes. The copper atom has a plane square environment of two oxygen atoms (Cu–O 1.93 ) and two nitrogen atoms (Cu–N 1.90 ). The O–Cu–N chelate angle is 91.7°. The complex has an intramolecular hydrogen bond, N–H...O 2.16 , involving the alkoxy oxygen atom. The molecular packing in the crystal is close to that of copper(II) dipivaloylmethanate. The calculated van der Waals intermolecular interaction energies and thermogravimetric characteristics of the complexes are compared.     

Synthesis and structure of isomeric (μ-H)Os<Subscript>3</Subscript>(μ,η<Superscript>2</Superscript>-(O,N)-6,6-clusters of dimethyl-2-methylene-bicyclo[3.1.1]heptan-3-one oxime)(CO)<Subscript>10</Subscript>. Crystal structure of one of the isomers

(-H)₂Os₃(,²-(O,N)-6,6-dimethyl-2-methylene-bicyclo[3.1.1]heptan-3-one oxime)(CO)₁₀ isomeric clusters have been synthesized, separated chromatographically, and investigated by IR and NMR spectroscopy. The crystal structure of one of the isomers has been determined (Enraf-Nonius CAD-4 automatic diffractometer, graphite monochromator, MoK , /2 scan mode at a variable rate). The crystals are monoclinic with unit cell parameters: a = 9.125(2) , b = 13.629(3) , c = 10.098(2) , = 90.16(3)°, V = 1255.8(4) ³, space group P2₁, Z = 2, composition (-H)₂Os₃(,²-ONC₁₀H₁₄)(CO)₁₀, d _calc = 2.647 g/cm³. The structure is molecular; the planes of the Os₃ triangle and the OsONOs bridging ligand are linked according to the butterfly pattern with an angle of 102.0° between the planes. The Os-Os bonds vary within the range 2.840 –2.882 .Original Russian Text Copyright © 2004 by V. A. Maksakov, N. V. Pervukhina, S. V. Korenev, N. V. Podberezskaya, V. P. Kirin, and A. V. TkachevTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 698–705, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Crystal and Molecular Structure of Monoammonium Salt of 5‐nitroaminotetrazole

Xray structural investigation of the monoammonium salt of 5nitroaminotetrazole was performed. The crystals are orthorhombic: a = 10.077(1), b = 17.009(1), c = 6.6472(6), V = 1139.33(17)³, space group Pbca, Z =8, _calc = 1.715 g/cm³. Monodeprotonation of 5nitroaminotetrazole during formation of the salt occurs at the N(4) nitrogen atom of the heterocycle. The anion has an almost flat structure; the bond lengths suggest delocalization of electron density in the molecule. The negative charge is distributed among three nitrogen atoms and two oxygen atoms of the anion. Changes in the geometrical parameters of 5nitroaminotetrazole on monodeprotonation are considered.     

Crystal and Molecular Structure of 5,7,12,14-Tetramethyl-1,4,8,11-tetraaza-4,6,11,13-tetraenatogold(III) Bromide [Au(C14H22N4)]Br

The crystal and molecular structure of [Au(C₁₄H₂₂N₄)]Br has been determined. Monoclinic crystals, a=12.592(2), b=6.309(1), c=19.628(2) ; =98.00(1)°, V=1544.1(4) ³, Z=4, d_calc=2.251 g/cm³, space group C2/c. The structure consists of virtually planar centrosymmetric [Au(C₁₄H₂₂N₄)]⁺ cations and Br^- anions. The coordination sphere of the gold atom involves four nitrogen atoms of the ligands, forming a planar square. The Au–N bond lengths are equal (the mean length is 1.982(7) ). The C–C and C–N bonds inside the -diiminate rings are delocalized. The parameters of the -diiminate rings of the [Au(C₁₄H₂₂N₄)]⁺ cation are compared with the parameters of the related complexes.     

Synthesis and Crystal Structure Investigation of Trinitrotriamminerhodium(III) [Rh(NO2)3(NH3)3]

Synthesis of the complex [Rh(NO₂)₃(NH₃)₃] is described. The compound crystallizes as monoclinic colorless plates. Crystal data: a = 7.176(10), b = 10.407(2), c = 10.989(2) , = 93.27°, V = 819.3(2) ³, space group , Z = 4, d _calc = 2.367 g/cm³. The structure is molecular and built of neutral complexes having cis-facial configuration. The unit cell of the crystal contains two independent complexes.     

Hydrogen bonding in ε-caprolactam dimer: a quantum-chemical study

The equilibrium geometries, vibrational frequencies, and IR band intensities were calculated for the monomer and hydrogen-bonded cyclic dimer of -caprolactam (1) by the density functional B3LYP/6-311++G(d,p) method and compared with the experimental data. The gas phase IR spectrum of monomer of 1 was first measured. The calculated hydrogen bonding enthalpy H/2 in the hydrogen-bonded dimer in the gas phase (–5.93 kcal/mol) is consistent with the published data. The computed scaled (scaling factor 0.97) vibrational frequencies of the monomer and dimer are in good agreement with the experimental data. The geometry of the -caprolactam monomer remains nearly unchanged in its dimer except for the N-H, C-O, and C-N bond lengths that respectively change from 1.012, 1.230, and 1.369 in the former to 1.029, 1.246, and 1.350 in the latter. The frequencies, eigenvectors, and IR intensities of the amide modes of the monomer and dimer differ dramatically. The calculated NH and CO frequency shifts due to hydrogen bonding are in good agreement with the experimental data, but theoretical intensification of the NH IR band is much greater than that observed experimentally (by nearly 69 times vs. 11 times, respectively). The calculated N...O intermolecular distance in the structure of -caprolactam dimer equals the experimental value (2.89 ). The influence of the basis set employed on the results of calculations is discussed.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1818–1825, September, 2004.     

Crystal Structures of Two New Holmium Polysulfides in the Series of Rare-Earth Polychalcogenides

The crystal structures of two polysulfide phases HoS_1.885(5) (I) and HoS_1.863(8) (II) were determined; the integer stoichiometric ratio was found to be Ho₈S₁₅. The data were collected on an Enraf-Nonius CAD-4 automatic diffractometer using the standard procedure (MoK, graphite monochromator, an absorption correction applied based on -scan data). Crystal I: space group P4/nmm, a = 3.820(1), c = 7.840(3) , V = 114.40(6) ³, Z = 2 for the composition HoS_1.885(5), d _calc = 6.542 g/cm³, R = 0.0520 for 184 unique reflections with I_hkl > 2 _I; crystal II: space group P2₁/m, a = 10.961(2), b = 11.465(2), c = 10.984(2) , = 91.27(3)°, V = 1380.0(4) ³, Z = 24 for the composition HoS_1.863(8), d _calc = 6.486 g/cm³, R = 0.0596 for 5354 unique reflections with I_hkl > 2 _I. In both compounds, the Ho atoms are surrounded by 9 (8+1 for three atoms in II) S atoms forming monocapped square antiprisms. The Ho–S distances vary from 2.717 to 3.067 irrespective of the type of ion [S^2– or (S₂)^2–]; the maximal distance to the atoms completing the coordination is 3.684 . The compounds have PbFCl type structures composed of ...(S₂)^2–...Ho³⁺...S^2–...S^2–...Ho³⁺...(S₂)^2–... layer packets differently oriented in space relative to the unit cell axes. The S^2–...S^2– and S^2–...(S₂)^2– interlayer distances are mostly shorter than the sum of the ionic radii and vary within the limits of 3.331-3.558 and 3.029-3.784 for the first and second types, respectively. For I, the calculated site occupancies and densities are given depending on the composition Ho-S_2-x (x = 0.25-0); for II, the most probable formulas of rational compositions in the same range of x are presented.     

Hydrothermal Synthesis and Structure of Organically Templated One‐Dimensional and Three‐Dimensional Iron Fluorophosphate

Two new openframework iron fluorophosphates, [C₄N₂H₁₂]_0.5[FeF(HPO₄)(H₂PO₄)] (I) [C₄N₂H₁₂][Fe₄F₂(H₂O)₄(PO₄)₄] · 0.5H₂O (II), were synthesized hydrothermally using piperazine as a templating agent. The structures were determined by singlecrystal Xray diffraction. Compound I crystallizes in the orthorhombic space group Pbca, a = 7.2126(2) , b = 14.2071(4) , c = 17.1338(2) , Z = 8. The structure is composed of infinite anionic chains of [FeF(HPO₄)(H₂PO₄)]^- _n built by transfluorine sharing FeF₂O₄ octahedra. These chains are similar to those found in tancoitetype minerals. Compound II crystallizes in the monoclinic space group P2₁/n, a = 9.9045(3) , b = 12.3011(3) , c = 17.3220(4) , = 103.7010(10)°, Z = 4. The structure of compound II has a threedimensional (3D) architecture with an eightmembered channel along the b axis, in which protonated piperazine molecules reside. The complex framework is built from two types of secondary building unit (SBU): one hexamer [Fe₃F₂(H₂O)₂(PO₄)₃$] (SBU6), and one dimer [FeO₄(H₂O)₂PO₄] (SBU2). The vertex sharing between these SBUs create the 3D structure.     

Coordination chemistry of alkali and alkaline earth cations: Synthesis and X-ray crystal structure of cesium (picrate) (benzo-15-crown-5) Cs+C6H2N3O 7 − (C14H20O5)

Crystals of the Cs⁺ Pic^– (B15C5) complex (Pic=picrate; B15C5=benzo-15-crown-5) (M _r =629.3) are yellow prisms which belong to the triclinic space groupP witha=7.377(4),b=11.372(2),c=14.806(2) , =90.31(1), =91.06(2), =108.32(2)⁰,Z=2,D _x =1.77, andD _m =1.77 g cm^–3. FinalR=0.055 for 3575 observed reflections out of a total of 4004 measured reflections. Cesium forms a 1:1 anion paired complex with B15C5 like sodium rather than a charge separated sandwich structure as found for potassium and expected for cesium in view of the ion-cavity radius concept. The Cs cation is 9-coordinate involving the five crown oxygens (Cs...O, 3.00(1) to 3.24(1) ), the phenoxide (Cs...O^–, 3.03(1) ) and anortho nitro group oxygen (Cs...O, 3.01(1) ) of the picrate counteranion and, uniquely, with two additional oxygens (Cs...O, 3.17(1) and 3.40(1) ) from apara nitro group of the picrate belonging to the adjacent molecule in the lattice. The Cs⁺ ion lies 2.07 out of the mean plane formed by the crown oxygens. This system provides the first structural evidence that the interaction stoichiometry of an alkali cation with a cyclic multidentate ligand is not a function of the ion and cavity size alone but also of its Lewis acid strength as modified by the charge neutralizing anion. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82027.     

Synthesis and X‐Ray Study of Single Crystals of K5(Cd0.5Zr1.5)(MoO4)6 Triple Molybdate

Single crystals of K₅(Cd_0.5Zr_1.5)₂(MoO₄)₆ molybdate have been grown. Its composition and crystal structure have been established from Xray diffraction data CAD4 automatic diffractometer, MoK radiation, 940 F(hkl), R = 0.0234. The crystals have a trigonal unit cell a = b = 10.624(1), c = 37.694(6), V = 3684.5(8)³, and space group R3c. The 3D mixed framework of the molybdate structure is formed by two kinds of Mo tetrahedra and (Cd, Zr) octahedra joined by shared O vertices. The large cavities in the framework are occupied by K atoms of three kinds. The distribution of Cd²⁺ and Zr⁴⁺ cations over two crystallographic positions has been refined.     

Culcitosides C2 and C3 from the starfishCulcita novaeguineae

Two steroid glycosides not previously described have been isolated from the digestive system of the starfishCulcite novaeguiniae, and these have been called culcitosides C₂ and C₃. With the aid of chemical and spectral methods, the chemical structure of C₂ has been established as 24-methyl-5-cholestane-3,4,6,8,15,16,28-heptaol 28-O-[O-(2,4-di-O-methyl--D-xylopyranosyl)-(1 2)--L-arabinofuranoside, and that of C₃ as its 4-deoxy analogue.Pacific Ocean Institute of Bioorganic Chemistry of the Far Eastern Scientific Center of the USSR Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 592–596, September–October, 1986.     

Kinetics of Co?Mo/Al2O3 catalyst reduction

According to kinetic studies on the reduction of commercial Co–Mo/Al₂O₃ and model catalysts in H₂ at 523–773 K, the kinetic curves for the reduction process have been determined. The reduction rate is shown to be higher for the commercial catalyst. Activation energies E_act for the reduction of several forms of Mo and Co in Co–Mo/Al₂O₃ catalysts are presented.

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H₂ 523–773 . , : Mo Co .