The crystal structure of bisphenoxatelluronium dinitrate,C24H16O9N2Te2

Bisphenoxatelluronium dinitrate is monoelinie, P2₁/c: a = 11.638(4), b = 28.266(8), c = 8.546(3) å, β = 119.73(2)°, z = 4 at t = 22°. All atoms including hydrogen were located. The two ring systems, I and II, are folded along their Te-O axes, 147° and 163°, respectively. The average ring bond distances are: Te-C = 2.091, C-C = 1.377, C-O = 1.370 Å. Each Te is bonded to one NO₃ group, Te1-ON1 = 2.485(5), Te2-ON4 = 2.393(4) Å, and an oxygen bridge connects the ring systems, Te1-OB = 1.966(4), Te2-OB = 2.001(4) Å, Te1-OB-Te2 = 125.0(2)°. The bond distances and angles of the structure are compared to those of related compounds.     

Crystal and molecular structure of potassium cyanurate,KC3H2N3O3·H2O

All-Union Research Institute for Chemical Reagents and High-Purity Chemicals. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 4, pp. 90–96, July–August, 1990.     

Crystal structure and standard molar enthalpy of formation of ethylenediamine dilauroleate (C12H24O2)2C2N2H8(s)

The crystal structure of ethylenediamine dilauroleate was determined by X-ray crystallography. A thermochemical cycle was designed in accordance with Hess law. The enthalpy change of the synthesis reaction of ethylenediamine dilauroleate was determined to be $ \Updelta_{{\text{r}}} H_{{\text{m}}}^{\Uptheta } $ Δ r H m Θ  = ?(49.07 ± 0.11) kJ mol^?1 by an isoperibol solution–reaction calorimeter. The standard molar enthalpy of formation of the title compound was calculated to be $ \Updelta_{\text{f}} H_{\text{m}}^{\Uptheta } $ Δ f H m Θ  = ?(38.78 ± 0.43) kJ mol^?1 by the designed thermochemical cycle, the enthalpies of dissolution and other auxiliary thermodynamic quantities.     

[(C2H5)4N]2{Fe4S4[S2CN(C2H5)2]4}的晶体和分子结构

[(C2H5)4N]2{Fe4S4[S2CN(C2H5)2]4}单晶样品在Nicolet-R3四圆衍射仪上收集X射线衍射数据. 分析结果给出其晶胞参数: a=22.125(6), b=11.313(3),c=25.053A; β=118.05(2)°; V=5534.19A^3, Z=4, 空间群Cc. 衍射数据经过Lρ因子和经验吸收效应校正. 分子中铁原子的位置从三维Patterson图上得到. 接着经过若干轮Fourier和差Fourier电子云密度合成, 发现全部其余非氢原子的坐标.氢原子位置根据理论模型计算. 结构修正最后收敛至R=0.073, Rw=0.069. 标题化合物是由[(C2H5)4N]^+和{FeS4[S2CN(C2H5)2]}^2^-组成的离子型化合物. 结构的主要特点表现在阴离子上, 而在阴离子中含有类立方烷型簇核Fe4S4. 该簇核中每个铁原子与五个硫原子配位, 其配位多面体构型均为畸变的四方锥.     

Crystal structure of (C2H7N4O)2[UO2(C2O4)2(H2O)]

The single crystals of (C₂H₇N₄O)₂[UO₂(C₂O₄)₂(H₂O)] were studied by X-ray diffraction. The crystals are monoclinic, space group Pn, Z = 2, unit cell parameters: a = 9.4123(2) Å, b = 8.4591(2) Å, c = 11.8740(3) Å, β = 105.500(10)°, V = 911.02(4) ų. The main structural units of the crystals of I are islet complex groups [UO₂(C₂O₄)₂(H₂O)]^2? corresponding to the crystal chemical group AB ₂ ⁰¹ M¹ (A = UO UO ₂ ²⁺ , B⁰¹ = C₂O ₄ ^2? , M = H₂O) of uranyl complexes. Uranium-containing mononuclear complexes are connected into a three-dimensional framework through the electrostatic interactions and hydrogen bonding system involving carbamyolguanidinium ions.     

Crystal and molecular structure of polyunsaturated macrobicyclic carbosilane C24H38Si6

The crystal and molecular structure of the polyunsaturated macrocyclic carbosilane 1,4,4,7,7,10,13, 13,16,16-decamethyl-1,4,7,10,13,16-hexasilabicyclo-[8.8.2]-eucosa-5,14-diene-2,8,11,17-tetrain containing SiC(sp), SiC(sp ²), and SiC(sp ₃) endocyclic bonds was studied by XRD. The two strained 12-membered rings of this molecule have different (trans-zigzag and staggered) conformations. The lengths of the endocyclic bonds SiC(sp) are 1.821–1.852 Å, SiC(sp ²) 1.855–1.874 Å, and SiC(sp ³) 1.847–1.853 Å. The structure of the rings was solved by direct methods and refined by the full-matrix least-squares method. Calculations were carried out with SHELXTL PLUS 5.1 software.     

Crystal and molecular structure of aspartame X HCl X 2H2O

The crystal and molecular structure of the hydrochloride salt of the peptide sweetener aspartame (alpha-L-Asp-L-Phe methyl ester) has been determined at 120 K using 3877 reflections with I greater than 2.5 sigma I. Space group P2(1)2(1)2(1), cell dimensions a = 6.768(1), b = 9.796(1) and c = 26.520(3) A; final R factor 0.033. While the N-terminal L-Asp group in the structure of aspartame itself forms a six-membered ring with an intramolecular hydrogen bond between the carboxylate and the protonated amino terminus, the corresponding group in the hydrochloride adopts a completely different conformation with a weak intramolecular hydrogen bond between the carboxyl group and the N atom of the L-Phe residue. The L-Phe methyl ester moiety is rather similar in the two structures. Of the many possible conformations of aspartame, only one may be expected to function as a substrate at the receptor site for sweet taste, and a proposal is made for this active conformation.     

Structures of [(n-C4H9)2NH2]2Cd9Cl20.2H2O and [Cu(C14H24N4)]2Cu13Cl30(H2O)2.xH2O: perforated layer structures based on the CdCl2 layer network

The crystal structures are reported for two compounds containing novel perforated layer structures, [DBA] 2Cd 9Cl 20.2H 2O and [Cu(TIM)] 2Cu 13Cl 30(H 2O) 2. xH 2O, where [DBA] (+) = di n-butylammonium and TIM = 2,3,9,10-tetramethyl-1,3,8,10-tetraenecyclo- 1,4,8,11-tetraazatetradecane. In the former compound, single Cd (2+) ions are excised from the parent CdCl 2 layers, with water molecules hydrogen bonded to chloride ions on both sides of the excision. Lattice stability is provided by the DBA (+) cations, which have an all-trans conformation. These lie between the layers, hydrogen bonding to the adjacent [Cd 9Cl 20(H 2O) 2] n (2 n- ) sheets. In the copper compound, the modification of the parent CuCl 2 structure is much more complex. In this compound, [Cu 2Cl 2] (2+) moieties are excised in a regular fashion. In addition, at 50% of the Cu1 sites, CuCl 2 species are replaced by pairs of water molecules in a random fashion. The Cu(TIM) (2+) cations bridge the layers via the formation of two semicoordinate bonds to chloride ions at the edge of the [Cu 2Cl 2] (2+) excision sites of adjacent layers.