Crystal Structure of Rb2CoCl4 and Rb3Mn2Cl7

Previously published cell dimensions of Rb₃Mn₂Cl₇ are confirmed and atomic positions are given. The crystal structure of low temperature Rb₂CoCl₄ is reported. The material was found to belong to the orthorhombic system, space group Pnma with a = 9.272 ± 0.006 Å, b = 7.283 ± 0.004, c = 12.723 ± 0.006 Å and Z = 2.     

Reversible Carbon-Carbon Bond Cleavage of a 3-Vinyl-1-Cyclopropene by Rh(I). Molecular Structures of Two Sterically Crowded 1,2,3,5-η-Pentadienediyl Complexes of Rh(III)

1,2,3-Tri-tert-butyl-3-vinyl-1-cyclopropene 6a reacts with [RhCl(C₂H₄)]₂ to give the dimeric 1,2,3,5-η-pentadienediyl complex 7a . The cyclopentadienyl derivative of this complex, 8a , is obtained by reaction of 7a with T1(C₅H₅). Crystal structures of both 7a and 8a were determined: 7a ; orthorhombic, Pbcn, a = 28.136 (4) Å, b = 10.637 (2) Å, c = 12.154 (2) Å, V = 3637.6 (1.2) ų, and Z = 4 : 8a ; triclinic, P 1 -bar, a = 9.906 (2) Å, b = 9.736 (2) Å, c = 12.126 (2) Å, α = 76.07 (2)°, β = 78.21 (2)°, γ = 65.34 (2)°, V = 1024.6 (3) ų, and Z = 2. Treatment of 7a with one equivalent of PMe₃ per Rh center results in regeneration of the vinylcyclopropene, demonstrating the reversibility of the ring opening reaction. Deuterium labelling studies show that both the ring opening and closing reactions proceed with retention of configuration at the vinyl olefin. Thus the trans-deuterated vinylcyclopropene 6b reacts with [RhCl(C₂H₄)₂]₂ to give 7b in which deuterium is located exclusively in the syn position. Treatment of 7b with T1(C₅H₅) yields 8b . Treatment of 7b with one equivalent of PMe₃ per Rh center results in formation of 6b as the sole organic product. Unlike their triphenyl relative 2 , the tri-Bu complexes 7a , 7b, 8a , and 8b are stereochemically rigid in solution at room temperature, and do not undergo an η³ → η¹ → η³ isomerization on the NMR time scale. However, after prolonged heating, syn-anti site exchange of H and D slowly takes place with 8b .     

X-Ray crystal structure of the Dye 2,4,6-Tricyano-4'-N,N-diethylaminoazobenzene

The crystal structure and molecular conformation of 2,4,6-tricyano-4'-N,N-diethylaminoazobenzene (C₁₉H₁₆N₆, mol. wt. 328.4a.m.u.) has been determined from X-ray diffraction data: monoclinic P2₁/c, a = 9.302(7)Å, b = 8.733(5)Å, c = 20.98(1) Å, β = 94.93(6)°, V = 1699(2)ų, Z = 4, D_c = 1.284gem^?3, F(000) = 688, λ(MoKα) = 0-71069Å, μ(MoKα) = 0.76cm^?1. The structure was solved by MULTAN andrefined by full-matrix least-squares toR = 0.050 for 1358 independent observed reflections. The azobenzene skeleton is planar to within 0.12Å. Most significant bonding data are: NN, 1.286(4) Å; mean C-N (azo) 1.383(4) Å; mean C-C (cyano) 1.439(5) Å; mean CN 1.146(5)Å; NN-C, 112.8(2)° and 115.9(2)°; N-C-C (cis relative to NN) 127.6(2)° and 124.3(2)° ; N- C- C(trans) 115.2(2)° and 117.7(2)°.     

Thermal Decomposition of Energetic Materials XXIV. A comparison of the crystal structures,IR spectra,Thermolysis and impact sensitivities of nitroguanidine and trinitroethylnitroguanidine

The crystal structure of trinitroethylnitroguanidine (TNENG) was determined by X-ray diffraction for comparison with nitroguanidine (NGu). Pertinent crystal parameters are: orthorhombic, Pbca, a = 14.611 (7) Å, b = 11.973 (5) Å, c = 11.452 (5) Å, V = 2003 (2) ų, Z = 8, D(calcd) = 1.758 g/cm³, R(F) = 6.30%, R(wF) = 6.58%. A hydrogen bonded network like that present in NGu is largely responsible for the lattice cohesion of TNENG. The IR spectrum of the condensed phase using slow thermolysis, and the gas phase using slow and fast thermolysis, suggests that parallel C N and N N bond fission reactions take place in both TNENG and NGu. The calculated and experimental values of the impact sensitivity of TNENG and NGu are compared. We conclude that the impact sensitivity and the thermal decomposition of TNENG are dominated by the characteristics of the  C(NO₂)₃ group. The intermolecular hydrogen bonding that may desensitize nitroguanidine to impact has essentially no stabilizing effect on TNENG.     

Molekül- und KristallStruktur des Dioxano-bis(2,4-dichlorphenoxyacetato)-kupfer(II) Cu2(2,4-D)4 · 5 Dioxan

Molecular and Crystal Structure of Dioxano-bis(2,4-dichlorophenoxyacetato)-copper (II) Cu₂(2,4-D)₄ · 5 Dioxan The cupric salt of 2,4-D crystallizes from dioxane solution in the space group P 1 with 2 formula units C₁₆H₁₀O₆Cl₄Cu and 5 dioxane molecules in the unit cell. The lattice constants are a = 12.557 Å, b = 14.391 Å, c = 9.537 Å, α = 112.56°, β = 99.62° and γ = 92.77°. By X-ray structure analysis the coordination around the Cu atoms was especially investigated.     

Synthesis of single azo disperse dye containing double ester and determination of crystal structure

The synthesis, crystal structure analysis and characterization of a monoazo dye, 4-((2,6-dichloro-4-nitro phenyl)azo)-N-(diacetyl oxygen ethyl)aniline, are reported. The dye crystallised in the triclinic system, space group P-1 with a=8.1663(3) Å, b= 9.4222(3) Å, c=15.4694(5) Å, α=78.9130(10)°, β=75.019(2)°, γ=70.787(2)°, V=1078.26(6) ų and Z=2. There is only one molecule in the asymmetric unit. The dihedral angle between the two phenyl rings is 53.4 Å. In the crystal structure, intermolecular C-H…O hydrogen bonds link the molecules into centrosymmetric dimers, forming R₂₂(30) ring motifs, in which they may be effective in the stabilization of the structure. Between the phenyl rings, the π…π stacking (interactions) may further stabilize the structure.     

Stereochemische Untersuchungen heterocyclischer Verbindungen. XII. Kristall- und Molekülstruktur von 1-(2-Amino-1-cyano-2-thio-ethylen)pyridiniumyliden

Stereochemical Investigations of Heterocyclic Compounds. XII. Structural Investigations of 1-(2-Amino-1-cyano-2-thio)ethene Pyridinium Ylides Two isomerization processes were found by ¹H-d-n. m. r. characterized by ΔG^* = 67 ± 4 KJ/mol for E- Z-isomerization and ΔG^* = 46 ± 5 KJ/mol for the hindered rotation of the pyridine substituent in 1a . The structure of 1b was solved by direct method. Crystals are monoclinic space group P2₁/n, a = 13.682(3), b = 9.452(1), C = 19.713(6) Å, β = 96.42(2)°, V = 2533.3 ų, D_x = 1.328 Mg · m⁻³, Z = 8. Both E- and Z-isomeres of 2b are found in the crystal lattice. The amino C distance with 1.369 (1,387) Å is shorter than the theoretical single bond distance. The formal  CC double bond with 1.377 (1.391) Å is considerably longer than 1.337 Å observed in the some alkenes.     

X-ray crystal structure of the dye 2-bromo-4-cyano-4′-N,N-diethylaminoazobenzene

The crystal structure of 2-bromo-4-cyano-4′-N,N-diethylaminoazobenzene has been determined from X-ray diffraction data: C₁₇H₁₇N₄Br, mol. wt = 357·1. Triclinic, Pī (No. 2), α = 13·162(5) Å, b = 7·516(3) Å, c = 8·496(4) Å, α = 101·63(4)°, β = 95·79(4)°, γ = 91·49(4)°, V = 818·10 ų, Z = 2, D_c = 1·45 g cm^?3, F(000) = 378, λ(Mo_Kz) = 0·7107 Å, μ(Mo_Kα) = 26·70 cm^?1. The structure was solved by direct methods and refined by full-matrix least-squares to R = 0·053 for 2081 independent reflexions. The molecule possesses an essentially planar azobenzene skeleton. The effects of substituents on the geometry of the azo group are discussed. Significant molecular parameters are: NN, 1·264(6) Å; ₁BrC, 1·904(5) Å; mean NC, 1·410(7) Å; NNC, 115·7(2)° and 113·0(2)°; NCC (cis relative to NN), 125·4(3)° and 123·1(2)°; CC(Br)C, 123·0(2)°.     

The Preparation and Crystal Structure of TlMnCl3, TlFeCl3, TlCoCl3 and TlNiCl3

The compounds TlMnCl₃, TlFeCl₃, TlCoCl₃ and TlNiCl₃ were prepared by heating T1C1 with the corresponding transition metal dichloride in an evacuated ampoule. Atomic positions were determined from powder photographs. All four compounds were found to be related to the perovskite type structure. TlMnCl₃ has a cubic structure, space group Pm3m, with a_o = 5.025 Å. The other three compounds are hexagonal, probable space group P6₃mc, with cell dimensions (in Å) a₀ = 6.976 and c₀ = 6.008 for the Fe compound, a₀ = 6.907 and c₀ = 5.981 for the Co compound and a₀ = 6.863 and c₀ = 5.881 for the Ni compound. The three hexagonal compounds are isomorphous. A measureable concentration of basal plane stacking faults was found to occur in TlFeCl₃ and also, to a lesser degree, in TlCoCl_3.     

BaO−B2O3 system and its mysterious member Ba3B2O6

The first systematic study of the BaO–B₂O₃ system and barium orthoborate Ba₃B₂O₆ (3BaO·B₂O₃) was reported in 1949. Thereafter, the system was repeatedly refined but the structure of Ba₃B₂O₆ compound has not been adequately studied yet. In our study we have, for the first time, obtained the crystalline samples of Ba₃B₂O₆. The solved structure (Pbam, a = 13.5923(4) Å, b = 13.6702(4) Å, c = 14.8894(3) Å) belongs to the class of ‘anti‐zeolite’ borates with a pseudotetragonal [Ba₁₂(BO₃)₆]⁶⁺ cation pattern which contains channels along the c axis filled with anionic clusters. The Ba₃B₂O₆ compound may be regarded as a fluorine‐free end‐member of the Ba₃(BO₃)_2–xF_3x solid solution. The BaO–B₂O₃ phase diagram presented in our study is based on our research and literature data.     

X-ray crystal structure of the dye 2-cyano-4-bromo-4′-N,N-diethylaminoazobenzene

The crystal structure and molecular conformation of 2-cyano-4-bromo-4′-N,N-diethylaminoazobenzene (C₁₇H₁₇N₄Br, mol. wt. = 357·2 a.m.u) has been determined from X-ray diffraction data; triclinic, P$\text{1}$ (No. 2), a = 10·132(11) Å, b = 12·216(16) Å, c = 6·966(11) Å, α = 104·21(9)°, β = 92·67(12)°, γ = 97·22(7)°, V = 826·5(9) ų, Z = 2, D_c = 1·436 g cm^?3, F(000) = 378, λ(MoKα) = 0·71069 Å, μ(MoKα) = 26·0 cm^?1. The structure was solved by the multiple solution direct method and refined by full-matrix least-squares to R = 0·059 for 1538 independent observed reflections. The azobenzene skeleton is planar to within 0·06 Å. Most significant bonding data are: NN, 1·290(8) Å; BrC, 1·866(6) Å; mean CN (azo) 1·380(8) Å; NNC, 113·6(4) and 115·3(4)°; NCC (cis relative to NN) 125·9(4)° and 126·7(4)°; NCC (trans) 116·8°(5)° and 116·1(4)°.     

Thermal Decomposition of Energetic Materials XVIII. Bis (cyanomethyl)nitramine and Bis(cyanoethyl)nitramine

The crystal structures of two potentially useful cyanonitramines are reported. Bis(cyanomethyl)nitramine (BCMN), (NCCH₂)₂NNO₂: monoclinic, C2, a = 10.247(1), b = 7.771(1), c = 12.230(2) [Å], β = 107.45 (2)^°, Z = 6, D_calc = 1.502 g.cm⁻³, R_F = 2.8%, R_wF = 3.1%. A syn (C₂) and anti (C_s) isomers of BCMN crystallize together in a 2:1 ratio in the unit cell. Bis(cyanoethyl)nitramine (BCEN), (NCCH₂CH₂)NNO₂: monoclinic, P2₁/c, a = 7.512(2), b = 10.840(3), c = 10.181(3) [Å], β = 97.39(2)^°, Z = 4, D_cale = 1.357 g.cm⁻³, R_F = 4.6%, R_wF = 4.7%. Only one conformation of the BCEN molecule having no symmetry is present in the unit cell. The IR spectrum shows that BCEN forms an amorphous phase when the melt is cooled or when an acetone or acetonitrile solution is rapidly evaporated. The amorphous phase slowly crystallizes at room temperature. High-rate thermolysis of BCMN liberates NO₂ as the predominant initial product. This difference is qualitatively predictable on the basis of the variation in the N-N bond distance in these two compounds.     

X‐ray crystal structure analysis for CI Disperse Orange 61

The synthesis, crystal structure analysis and characterisation of a monoazo dye, CI Disperse Orange 61, are reported. The dye crystallised in the triclinic system, space group P‐1 with a = 8.859(2), b = 9.899(2), c = 11.417(3)Å, α = 78.51(4)°, β = 70.37(3)°, γ = 80.46(4)°, V = 918.8(4)ų and Z = 2. There is only one molecule in the asymmetric unit. The two phenyl rings are oriented at a dihedral angle of 57.87(20)°. In the crystal structure, intermolecular C–H…N hydrogen bonds link the molecules into centrosymmetric dimers, forming R₂²(30) ring motifs, in which they may be effective in the stabilisation of the structure. The π…π stacking (interactions) between the phenyl rings may further stabilise the structure, with a centroid–centroid distance of 3.741(4)Å.     

Synthesis and Characterization of Hydrazinium Azide Hydrazinate

Hydrazinium azide hydrazinate, [N₂H₅]⁺[N₃]⁻ċN₂H₄ was synthesized from equimolar amounts of hydrazinium azide and hydrazine and characterized by single crystal X‐ray diffraction: monoclinic, P 2₁/c, a=6.3704(2), b=12.1111(4), c=6.9940(2) Å, β=91.8666(2) °, V=539.32(3) ų, Z=4, ρ=1.320 g cm⁻¹. The compound is less hygroscopic and less volatile than hydrazinium azide. Explosion of [N₂H₅]⁺[N₃]⁻ċN₂H₄ yielded dinitrogen (N₂), ammonia (NH₃) and dihydrogen (H₂). Compared to hydrazinium azide, the hydrazine adduct produces larger amounts of ammonia in the explosion.     

Medium-Ring Compounds 30. cis-1,6-Cyclodecanediol: Molecular Compounds with the trans Isomer and with Itself

The crystal structures of cis-1,6-cyclodecanediol ( 1 ) and of the molecular compound formed between cis and trans-1,6-cyclodecanediol in the ratio 2:1 (2) have been established by X-ray diffraction. The two substances are closely isostructural. (Crystal data: both monoclinic, P2₁/c, Z = 6; ( 1 ) a = 6.665(6), b = 18.074(3), c = 14.351(8) Å, β = 119.77(6)°, V = 1500(2) ų; (2) a = 6.679(8), b = 18.074(4), c = 14.314(10) Å, β = 119.64(8)°, V = 1502(3) ų). The asymmetric unit of the molecular compound contains one cis molecule in a general position and one trans molecule at a center of symmetry. In the crystal of the pure cis diol a set of disordered cis molecules mimics the corresponding centrosymmetric trans molecules in the molecular compound. The molecules have the stable BCB cyclodecane ring conformation, except for the disordered cis molecules, which have a conformation about 2 kJ mol⁻¹ higher in energy (molecular mechanics calculations). The intricate three-dimensional hydrogen-bond network found in both crystals is presumably especially favorable from an energetic viewpoint.     

Synthesis of iron aluminates and a new modification of aluminum oxide under shock waves from explosives (Review)

The results of an x-ray diffraction investigation of iron aluminate with unit cell parameter a = 8.090(4) Å, cation-defective iron aluminate Fe_0.5Al_2.23O₄ with a = 8.002 Å, and a new modification of aluminum oxide synthesized under shock waves from explosives containing aluminum are presented. Aluminum oxide can crystallize in the hexagonal system in a primitive lattice with a = 9.151(1) Å, c = 7.945(2) Å, V = 576 ų or in a tetragonal system in a primitive lattice with one-half the volume — a = 7.941(2) Å, c = 4.575(1) Å, V = 288 ų.     

Crystal structure,impedance and broadband dielectric spectra of ordered scheelite-structured Bi(Sc1/3Mo2/3)O4 ceramic

Bi(Sc_1/3Mo_2/3)O₄ ceramics were prepared via solid state reaction method. It crystallized with an ordered scheelite-related structure (a?=?16.9821(9)?Å, b?=?11.6097(3)?Å, c?=?5.3099(3)?Å and β?=?104.649(2)°) with a space group C12/C1, in which Bi³⁺, Sc³⁺ and Mo⁶⁺ are ?8, ?6 and ?4 coordinated, respectively. Bi(Sc_1/3Mo_2/3)O₄ ceramics were densifiedat 915?°C, giving a permittivity (ε_r) ～24.4, quality factor (Qf, Q?=?1/dielectric loss, f?=?resonant frequency) ～48, 100?GHz and temperature coefficient of resonant frequency (TCF)?～??68?ppm/°C. Impedance spectroscopy revealed that there was only a bulk response for conductivity with activation energy (E_a) ～0.97?eV, suggesting the compound is electrically and chemically homogeneous. Wide band dielectric spectra were employed to study the dielectric response of Bi(Sc_1/3Mo_2/3)O₄ from 20?Hz to 30?THz. ε_r was stable from 20?Hz to the GHz region, in which only ionic and electron displacive polarization contributed to the?ε_r.     

Solid-phase synthesis and characterization of rare-earth chromates

Simple chromates(V) MCrO₄ (M = Sc, Y, Gd, Er, or Yb) and chromate(V) vanadates Gd(CrO₄) _x (VO₄)_{1 ? x} have been synthesized by a solid-phase method. All compounds crystallize in the xenotime-type structure, space group I4₁/amd, Z = 4. The unit cell parameters have been calculated as follows: for GdCrO₄, a = 7.209(5) Å, c = 6.318(4) Å; for ErCrO₄, a = 7.088(2) Å, c = 6.231(1) Å; for YbCrO₄, a = 7.034(1) Å, c = 6.205(2) Å; for YCrO₄, a = 7.108(3) Å, c = 6.254(3) Å; and for ScCrO₄, a = 7.012(2) Å, c = 6.188(2) Å. Symmetry D _2d , established for the CrO₄ tetrahedron during the Rietveld structure refinement, is verified by IR spectroscopy. The MCrO₄ simple chromates are paramagnets; their magnetic moments range from 1.7 to 8.1 μ _B .     

Multinuclear Metal Carbonyl Alkoxide and Aryloxide Derivatives as Models for Metal Carbonyls Adsorbed on Metal Oxide Supports

The synthesis and characterization of two tungsten carbonyl dimers containing bridging alkoxide or aryloxide ligands are described. The crystal and molecular structures of [PPN]₂[W₂(CO)₈(OCH₂CF₃)₂], 1, and [Et₄N]₃[W₂(CO)₆-(OPh)₃]-CH₃CN, 2 , are reported and compared with the structures of tetranuclear tungsten derivatives previously described. The dimer 1 crystalizes in the triclinic space group P 1 with unit cell parameters a = 13.460(11) Å, b = 12.318(5) Å, c = 13.842(10) Å, α = 82.73(5)°, β = 59.11(5)°, γ= 80.09(5)°, V = 1938(2) ų, and Z = 1. The complex 2 crystalizes in the monoclinic space group P2₁/n with unit cell parameters a = 11.954(2) Å, b = 19.359(4) Å, c = 26.462(5) Å, β = 102.50(16)°, V = 5979(2) ų, Z = 4. Molecular modeling software was utilized to construct a tetranuclear derivative from 1 similar to the structurally characterized [W(CO)₃OH]₄₋⁴ tetramer. The two tetramers were found to possess similar molecular parameters. This supports the contention that dimers of type 1 are the precursors of the tetramers. Comparisons of the tungsten alkoxides and aryloxides with the behavior of W(CO)₆ on γ-alumina are provided.     

The missing Ce member of Ln4Al2O9 family of aluminates

Ce₄Al₂O₉, the last missing member of a family of lanthanide aluminates with 2Ln₂O₃–Al₂O₃ stoichiometry has been synthesized by the reaction between nanocrystalline CeO₂ and an amorphous Al₂O₃ at 850°C in hydrogen atmosphere. The Ce₄Al₂O₉ is isomorphous with known Ln₄Al₂O₉ (Ln = La, Nd–Lu) aluminates and its structure is: P2₁/c, a = 7.844 Å, b = 10.968 Å, c = 11.399 Å, β = 109.65. The volume of the unit cell of Ce₄Al₂O₉ synthesized in this work (923.6 ų) fits the pattern determined for other lanthanides, if cerium is present as Ce³⁺ ions. The compound exhibits paramagnetic behavior at 100‐400 K, but the effective moment of Ce ions (μ_eff = 1.36) is much less than 2.5 waited for Ce³⁺ ions. The effect is assigned primarily to the surface oxidation of Ce₄Al₂O₉ at ambient conditions, though the presence of certain fraction of tetravalent Ce ions in the structure of Ce₄Al₂O₉ may not be excluded.