Crystal structure of 4,5-dinitronaphthalic anhydride

The structure of 4,5-dinitronaphthalic anhydride was determined in three dimensions. The molecule is not planar, the carbonyl oxygens being out of the plane of the naphthalene ring system by -0·29 and 0·26 Å. Electronic and infrared spectra seem to indicate that this deviation is not peculiar to the crystalline state. The compound crystallizes in space groupP2₁/c with unit cell dimensions ofa = 8·096,b = 8·813,c = 15·11 Å, and = 92·47 °. The finalR index was 5·4%.     

Crystal structure of magnesioneptunite

The crystal structure of the new mineral magnesioneptunite (K_0.8Na_0.1?0.1)Na₂Li(Ti_0.39Mg_0.34Fe_0.27)₂(Ti_0.59Mg_0.22Fe_0.19)₂[Si₄O₁₁]₂(O,OH) from the xenolith of Verkhnechegemskaya caldera (Lakarga Mountain, North Caucasus) has been investigated by X-ray diffraction (XCalibur-S diffractometer, R = 0.0244): a = 16.3271(7) ?, b = 12.4788(4) ?, c = 9.9666(4) ? ?? = 115.651(5), V = 1830.5(1) ?³, sp. gr. C2/c, Z = 4, and ??_calcd = 3.152 g/cm³. The disordered distribution of Ti, Mg, and Fe atoms in the octahedra forming the basis of the cationic framework is established. It is shown that the isomorphic occupation of octahedral positions by cations of three types corresponds to the centrosymmetric crystal structure and is likely caused by the high-temperature crystallization of the mineral.     

Crystal structure of abrine

The crystal structure of abrine (N-methyl L-tryptophan, (C₁₂H₁₄N₂O₂) was determined by X-ray diffraction. Space groupP2₁2₁2₁,a=5.372(1),b=8.595(1) andc=24.082(2)Å,Z=4,D _m=1.30(4) gcm^–3,D _x=1.304 gcm^–3,R=0.039 andwR=0.042. The conformational parameters for this structure following the IUPAC nomenclature are=67.7(5)°, ₁=–175(4)°, K₂₁=105.2(7)° and ₂₂=–66.4(7)°; the atom C9 in the present structure is gauche to N15 andtrans to C12. The molecules exist in a zwiterionic form and are stabilized in the unit cell by N-HO hydrogen bonds.DCB contribution No: 797     

Crystal structure of cefadroxil

The crystal and molecular structure of Cefadroxil, (7-[[amino-(4-hydroxyphenyl)acetyl]amino]-3-methyl-8-oxo-5-thia-1-azabicyclo-[4.2.0]oct-2-ene-2-carboxylic acid monohydrate), C₁₆H₁₇N₃-O₅S.H₂O has been determined from single crystal X-ray diffraction data. The compound crystallizes in the orthorhombic space groupP2₁2₁2₁. The cell parameters area=11.065(3),b=11.221(4) andc=14.436(4)Å;M _r=381.41;V=1792(2)ų,z=4,D _x=1.339 Mg^–3;=1.84 cm^–1,F(000)=752,T=296 K,R=0.037 andR _w=0.037. The-lactam ring is not planar and the nitrogen atom in the-lactam deviates from the plane of the other three atoms attached to it by 0.224(4) Å. The thiazene ring is in the half-chair conformation. The molecules are stabilized by N-HO and O-HO hydrogen bonds.DCB contribution No. 800.     

Crystal structure of magnesioferrikatophorite

The crystal structure of the Na,Ca-amphibole magnesioferrikatophorite found in carbonatites from the Turiy Cape (Kola Peninsula) was refined (Siemens P4 diffractometer, λMoK _α radiation, 1481 independent reflections with |F|>4σ(F), anisotropic refinement, R(F) = 0.039). The parameters of the monoclinic unit cell are a = 9.875(5) Å, b = 18.010(8) Å, c = 5.309(3) Å, β = 104.39(5)°, sp. gr. C2/m, Z = 2. The distribution of the cations over the crystallographically nonequivalent M(1–4)-positions was revealed by Mössbauer spectroscopy and X-ray diffraction analysis. The character of splitting of the A-position correlates with the characteristic features of the magnesioferrikatophorite composition. The resulting structural formula (Na_0.87K_0.13)_{Σ = 1} · (Na_1.18Ca_0.82)_{Σ = 2}(Mg_1.41Fe _0.42 ³⁺ Ti _0.17 ⁴⁺ )_{Σ= 2} Fe _1.31 ³⁺ Mg_0.69)_{Σ = 2}(Mg_0.60Fe _0.38 ²⁺ Mn_0.02)_{Σ = 1}(Si_3.16Al_0.84)_{Σ = 4} · Si₄O₂₂(O_1.05OH_0.66F_0.29)_{Σ= 2} agrees well with the electron microprobe analysis data. Based on the zonal character of the crystal and high Fe ³⁺ content, the conditions of crystallogenesis are defined as oxidative against the background of a decrease in the Na potential in the course of the evolution of a mineral-forming system.     

Crystal structure of sulfamerazine

The structure of sulfamerazine, C₁₁H₁₂N₄O₂S, a very important sulfonamide drug, has been solved by direct methods with X-ray diffraction data collected using CuK radiation. The crystals are orthorhombic, witha=9.145(1),b=11.704(1),c=22.884(2) Å and space groupPbca. The structure was refined with 2082 observed independent reflections, measured on a CAD-4 diffractometer, to a finalR value of 0.078. The molecule has similar conformational features to those observed in other sulfonamide drugs.     

Crystal structure of griseofulvin

The crystal and molecular structure of griseofulvin (C₁₇H₁₇ClO₆) has been determined. The antibiotic crystallizes in space groupP4₁, witha=8.967(2),c=19.904(9) Å andZ=4. The structure was solved by direct methods and refined to anR value 0.056. The 3-carbonyl and 6-methyl groups arecis, confirming Macmillan's assignment of stereochemistry. The molecular conformation is significantly different from that of the 5-bromo derivative. The methoxy substituents on the benzene ring are coplanar with the ring rather than clinal to it as in the 5-bromo derivative. The five-membered ring is only slightly puckered and the cyclohexanone ring has a half-chair conformation with the 6-methyl group oriented over the five-membered ring to a greater extent in griseofulvin than in the 5-bromo derivative.     

Crystal structure of terephthalaldehyde

Terephthalaldehyde forms monoclinic crystals, space group P2 ₁ /a, a = 12.698(6), b = 3.845(2), c = 14.764(3) Å, = 116.53(3)°, Z = 4, V = 645(1) ų, and Dx = 1.381(2) g cm^–3. There are two independent molecules, each located at a center of symmetry and approximately related to each other by pseudo-symmetry. In both molecules the rings are planar within experimental error. In one molecule the CHO groups are twisted out of the plane of the ring by 1.3(1)°, in the other by 0.6(1)°. Weak C–H···O hydrogen bonds occur at both independent aldehyde hydrogen atoms.     

Crystal structure of tetrahydrocortisol

The crystal structure of tetrahydrocortisol (3, 11, 17,21-tetrahydroxy-5-pregnan-20-one), C₂₁H₃₄O₅, has been determined by X-ray diffraction using CuK radiation. The crystals are orthorhombic, P2₁2₁2₁ witha=7.696(5),b=10.227(2),c=23.688(5) Å and Z=4. The structure was solved by direct methods and refined to a finalR-value of 0.053 with 1714 observed reflections. The rings A, B, C, D arecis, trans, andtrans fused, respectively. The rings, A, B, C, have almost perfect chair conformations and D has a distorted envelope conformation. The steroid skeleton as a whole is somewhat convex toward the -side. The molecules are held together by a three-dimensional network of hydrogen bonds. Despite the similar cell constants and common space group of the title compound with cortisone and 17-hydroxyprogesterone, they are not isostructural.     

Crystal structure of loparite

The crystal structure of the cubic modification of the natural mineral loparite has been studied for the first time by the methods of the X-ray diffraction analysis (γMoK _α radiation, 105 independent reflections with I > 3σ(I), R = 0.041 in the anisotropic approximation). The structure belongs to the perovskite type (ABO ₃) with the double period of the cubic unit cell, a = 7.767(1) Å (sp. gr. Pn3m; Z = 2 for the composition (Ca,Na,Ce)(Na,Ce)₃(Ti,Nb)₂Ti₂O₁₂. Period doubling is explained by ordering of cations both in the A and the B positions.     

Crystal structure of golyshevite

The crystal structure of golyshevite, a new calcium-and carbon-rich representative of the eudialyte group, was established by single-crystal X-ray diffraction analysis (sp. gr. R3m, a = 14.231(3) Å, c = 29.984(8) Å, R = 0.062, 1643 reflections with F > 3σ(F)). The idealized formula of golyshevite is (Na₁₀Ca₃)Ca₆Zr₃Fe₂SiNb[Si₃O₉]₂[Si₉O₂₇]₂(OH)₃(CO₃) · H₂O. This mineral is characterized by the presence of calcium atoms both in the octahedral positions of six-membered rings and in extraframework positions, where calcium prevails. CO₃ groups are present as the major additional anions. Carbon atoms randomly occupy two positions on the threefold z axis at a distance of 0.75 Å from each other and are coordinated by oxygen atoms arranged around the z axis.     

Crystal structure of nimbin

The crystal structure of nimbin has been determined. The crystals are orthorhombic, space groupP2₁2₁2₁ witha=6.790(2),b=14.875(4),c=27.160(8) Å andZ=4. The packing of the molecules in the lattice is due to C?H…O type of hydrogen bonds.     

Crystal structure of diselenadithiafulvalene

The crystal structure of diselenadithiafulvalene has been determined by direct methods, and refined by full-matrix least-squares techniques toR=0.119 based on 2393 unique reflections. The structure, which contains four crystallographically unrelated centrosymmetric molecules of diselenadithiafulvalene, apparently consists of a disordered equimolar mixture of the cis and trans isomers of this compound or, alternatively, of one of these isomers in two orientations.     

Crystal structure ofp-toluidinium bifluoride

p-toluidinium bifluoride crystallizes in the orthorhombic space groupPbca, witha = 7·161,b = 18·405,c = 11·824 Å andZ= 8. The structure was solved by direct methods from X-ray counter data measured with CuK. radiation, and a finalR index of 0·052 was obtained for the 642 observed terms of the 1480 possible. Thep-toluidine molecule is fully protonated and the methyl group is either disordered, librating extensively or freely rotating. In the HF₂ ^– ion the H atom is apparently centrally situated between the two fluorine atoms, and is obviously very delocalized; the F-H-F distance is 2·276 ± 0·005 Å. The structure consists of alternate layers ofp-toluidinium and hydrogenbifluoride ions with the latter hydrogen-bonded to the amine groupings.     

Crystal structure of monomethylammonium nitrate

The crystal and molecular structure of the title compound is reported. The crystals are orthorhombic:Pcmn, Z=4,a=6.414 (4),b=6.581 (4),c=10.412 (3) Å. The structure was solved by direct methods, and refined by full-matrix least squares toR=0.048 andR _w =0.044 for 296 unique reflections. Hydrogen bonds exist between the cations and anions. Differential scanning calorimetry and vibrational studies indicate phase changes at 355 and 245 K.     

Crystal structure of phosphorus-rich ellenbergerite

The phosphorus-rich variety of ellenbergerite (Mg_0.61Ti_0.08□_0.31)₂(Mg_0.52Al_0.43□_0.05)₁₂[SiO₃(O_0.29(OH)_0.71)]₆[(P_0.71Si_0.20□_0.09)O₃OH]₂(OH)₆ was studied by X-ray diffraction and IR spectroscopy. The structure was refined in sp. gr. P6₃ mc to R = 0.0248. The structure of phosphorus-rich ellenbergerite retains the octahedral framework observed in the structures of ellenbergerite, phosphoellenbergerite, ekatite, and a series of structurally related synthetic compounds. The structure of phosphorus-rich ellenbergerite differs from the structure of ellenbergerite primarily in that the Mg and Al cations in the phosphorus-rich variety are disordered in the octahedra of the framework, thereby leading to higher symmetry, and the channels of triangular cross section are occupied predominantly by P tetrahedra.     

Crystal structure of strontium hilgardite

The crystal structure of strontium hilgardite, CaSr[B₅O₉]Cl ? H₂O, was established by the method of X-ray diffraction analysis (synchrotron radiation; diffractometer equipped with a position-sensitive detector; λ = 0.688 Å; 3191 reflections with F < 4σ(F); R = 0.045 in the anisotropic approximation). The triclinic unit-cell parameters are as follows: a = 6.5732(6) Å, b = 6.4445(6) Å, c = 6.3693(6) Å, α = 60.995(2)°, β = 61.257(2)°, γ = 77.191(2)°, sp. gr. P1; Z = 1. The Ca and Sr atoms were found to be disordered over two positions. The structures of strontium hilgardite and hilgardite-1A differ in the configurations of the seven-vertex Sr-and Ca(2)-polyhedra. The structure solved in this work is consistent with two series of borates studied previously. One of these groups involves pentaborates with different degrees of hydration of borate complexes, and the second group includes Sr-containing borates.     

Crystal structure of acetylcholine perchlorate

The crystal structure of acetylcholine perchlorate has been determined from three-dimensional X-ray diffractometer data. The molecular geometry of this compound differs from that observed for acetylcholine bromide but is structurally similar to that observed for acetylcholine chloride.     

Crystal structure of holtite II

The crystal structure of the As-containing mineral holtite II was refined by the Rietveld method. The orthorhombic unit-cell parameters are a = 4.6893(1) Å, b = 11.881(1) Å, c = 20.394(1) Å, sp. gr. Pnma, Z = 4. Holtite II has an octahedral framework structure composed of two types of nonequivalent columns of Al octahedra, which was found in the structures of dumortierite-group minerals and holtite I. The differences in the structures of holtite II and holtite I were revealed. These differences are associated with the differences in the composition and configuration of the columns of Al(1) polyhedra, which are located inside the framework and are linked to SiO₄ tetrahedra, as well as with the arrangement of pyramidal SbO₃ groups.