The crystal and molecular structure of an epoxide,C30H50O

The compound C₃₀H₅₀O (7,8-epoxy-9(87)-abeofriedelane),M _r=376.33, orthorhombic, P2₁2₁2₁,a=11.819(1) Å,b=14.381(2)Å,c=15.402(2)Å,Z=4,D _c=1.083 gm cm^–3,R=0.055, for 1643 reflections (withI>2) out of 1743 unique reflections. The three dimensional structure determination is done to characterize the conformation of this series of compounds which has good promise for drug and for rational understanding of the reaction mechanism in the olefin stereochemistry and the structural basis of synthesis of these natural products.     

Refinement of the crystal structure of malonic acid,C3H4O4

A reinvestigation of the X-ray crystal structure of malonic acid (C₃H₄O₄) has been made in the light of some observations arising from solid-state¹³C NMR studies on this compound. The unit cell parameters are:a=5.156(1),b=5.341(1),c=8.407(1) Å, =71.48^o (2), =76.12^o (2), =85.09^o (2), space group ,Z=2. The structure was solved by direct methods and refined by full-matrix least-squares refinement to a finalR value of 0.038 for 711 unique reflections withl>3. The packing of the molecules involves dimeric hydrogen bonded association of each carboxyl group with a centrosymmetrically related neighbor. The angles O–C–O (123.3^o and 124.8^o, respectively) for the two carboxyl groups agree qualitatively with the values predicted from a linear relationship relating the observed ₂₂ component of the Carbon-13 NMR chemical shielding tensor for the carboxyl carbon atom to the bond angle O–C–O at the carbon atom.Contribution No. 825.     

Preparation,spectral studies and X-ray crystal structure of 1,3,5-triphenyl-1,5-pentanedione,C23H20O2

1,3,5-triphenyl-1,5-pentanedione, C₂₃H₂₀O₂, has been prepared and characterized by spectroscopic methods and single crystal X-ray analysis. Crystals are monoclinic, space groupP2₁/n, a=28.124(4),b=5.997(1),c=10.434(1)Å, -98.42(1)Å,Z=4. The structure has been refined to a finalR-value of 0.040 for 1625 reflections withF _o>3(F _o). The compound contains the two carbonyl groups in a mutuallycis arrangement.     

X-ray crystal structure of 2,5-dioxo-4-imidazolidineethanesulfonamide, C5H9N3O4S

The crystal structure of 2,5-dioxo-4-imidazolidineethanesulfonamide or homocysteine sulfonamide hydantoin, C₅H₉N₃O₄S (1) was obtained by single-crystal X-ray diffraction. Crystallization of 1 occurs in the centrosymmetric monoclinic space group C2/c (No. 15) with a = 15.653(2), b = 9.6489(10), c = 11.066(2) Å, = 94.64(2), and Z = 8. Molecules are in an extended structure with a C–C–C–S torsion angle of –174.2(1). The imidazolidinedione ring is planar and the sulfonamide group has a distorted tetrahedral geometry. A three-dimensional network of intermolecular hydrogen bonding occurs within the crystal lattice involving both imidazolidinedione and sulfonamide functional groups.     

Crystal structure of 17α‐acetoxyprogesterone,C23H32O4

The crystal structure of the title compound (C₂₃H₃₂O₄) has been determined by X‐ray diffraction methods. It crystallizes in the orthorhombic space group P2₁2₁2₁ with cell parameters: a = 10.86(1), b = 11.95(2), c = 15.65(5) Å and Z = 4. The structure has been refined to an R‐value of 0.045 for 1610 observed reflections. Ring A exists in sofa conformation, Ring B adopts a distorted chair conformation while as Ring C assumes a chair conformation. The five membered ring D adopts a half‐chair conformation. The crystal structure is stabilized by intra‐ and intermolecular C‐H…O interactions. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and crystal structure of [Nd(H2O)2]2(C2O4)3

Some crystals of [Nd(H₂O)₂]₂(C₂O₄)₃ were synthesized hydrothermally by heating at 200°C for 8 days an aqueous suspension of neodymium oxalate decahydrate in presence of terephthallic acid and guanidinium carbonate. They crystallize in the orthorhombic system, space group P2₁2₁2₁, with a = 8.6702(7) Å, b = 9.558(2) Å, and c = 17.009(2) Å. The structure of this complex is built up by two independent neodymium atoms, three bischelating oxalate ligands, and four water molecules forming a rectangle building unit of 6-membered ring, [Ln(H₂O)₂(C₂O₄)]₆. The packing of these units leads to a layer parallel to the plane (001). However, the neodymium atoms of two neighbor layers share an edge of oxalato oxygen atoms thus giving a double-layer. The three dimensionality between these double-layers is insured by hydrogen bonds of water molecules which are bound to the neodymium atoms. There is no zeolitic water molecule. The two neodymium atoms are nine-coordinated. In both cases, the coordination polyhedron can be described as a distorted tricapped trigonal prism.     

An improved crystal and molecular structure of guanidinium hydrogen oxalate monohydrate,C(NH 2)3HC2O4 · H2O

The title compound crystallizes in space groupP2₁/c witha = 6.6922 (25),b = 10.5468(8),c = 10.2125(19) Å, = 103.74(2) °, andZ = 4. The intensities were measured on an automated X-ray diffractometer, and the structure was refined to a finalR ₁ of 3.3% for 1106 reflections. The hydrogen bonding scheme is as reported by Adams (1978) with one additional bond found.     

The crystal and molecular structure of 1,12-dibromododecane,C12H24Br2

The α,ω-dihaloalcanes could serve as model compounds for polyethylenes in further studies of infrared and Raman-spectra. The 1,12-dibromododecane, belonging to this class of compounds, has the monoclinic space group P 2₁/a with the cell parameters a = 24.8 Å, b = 5.40 Å, c = 5.50 Å, β = 99°, Z = 2. The preparation of crystals was very difficult. The crystal finally used gives only few and bad X-ray data measured by film method (equiinclination Weissenberg). Therefore the accuracy of the structure determination is not high, but the result is reliable and has model character for related compounds. All molecules are ordered with their long molecular axes parallel to the (401) planes of the unit cell. There are alternating plane layers of bromine atoms on the one hand and aliphatic parts of the molecules on the other hand, both parallel to the (100)-planes. This molecular arrangement explains well the spectroscopic and crystal optical properties of the structure and also of related compounds like 1,10-dibromodecane and 1,18-dibromooctadecane.     

The crystal and molecular structure of (−)—Crinine (C16H17NO3)

(–)—Crinine, C₁₆H₁₇NO₃, is an alkaloid extracted from the bulbs of Pancratium maritimum L. (Amaryllidaceae). The compound crystallizes in the space group P2₁2₁2₁ with cell dimensions a = 6.040(1), b = 12.382(1), c = 17.861(2) Å, with Z = 4. The molecule has five rings and an OH group. The N-containing, five-membered ring and the D ring have envelope conformations. The A and B rings have distorted chair and half-chair conformations, respectively.     

Crystal and molecular structure of dichlorotetrakis(propanol-2) titanium (III) chloride,C12H32Cl3O4Ti

The crystal and molecular structure of dichlorotetrakis(propanol-2)titanium (III) chloride, C₁₂H₃₂Cl₃O₄Ti, has been determined by X-ray methods. The complex crystallizes in the monoclinic system:a = 15.968(4),b = 11.610(5),c = 11.90(5) Å, = 94.15(2) °, space groupC2/c andZ = 4. The positions of all non-hydrogen atoms have been refined by least squares to giveR = 0.126 for 1211 observed structure factors. The crystal structure consists of {TiCl₂(HOCH(CH₃)₂)₄}⁺ cations and Cl^– anions. From the space-group symmetry, it follows that the complex cation has 2(C ₂) symmetry. The 2 chlorine and 4 oxygen atoms of the inner coordination sphere are arranged in the form of a distorted octahedron around the central Ti atom. Two chlorine atoms, with the interatomic distance Ti—Cl of 2.32 Å, are in acis-conformation. The interatomic distances Ti—O, two oxygen atoms opposite to the chlorine atoms, are 2.10 Å. The pair oftrans-oriented oxygen atoms are at distances Ti—O= 2.09 Å. The Cl^– ions occupy positions at symmetry centres. Each of them is in contact with four oxygen atoms, the paired Cl—O distances being 3.04 Å and 3.12 Å.     

Synthesis and crystal structure of [Tb4(H2O)2](C2O4)2(C5H6O4)4

A terbium complex associating two ligands, oxalate and glutarate, was prepared under hydrothermal conditions at 200°C by treating an aqueous suspension of terbium oxalate decahydrate with glutaric acid and guanidinium carbonate. Its structure was solved by X-ray diffraction on a single crystal. It crystallizes in the monoclinic space group P2₁ with lattice constants, a = 9.514(1) Å, b = 9.0681(8) Å, c = 19.702(2) Å, and = 97.90(1)°. The terbium atoms and the oxalate ligands build dense chains which are connected by one side of the carboxylic group of some glutarate ligands, thus forming a sheet at the c level 0 and 1/2. These sheets are bridged by glutarate groups. The terbium atoms are ninefold coordinate with nine oxygen atoms of the ligands or with one water molecule and eight oxygen atoms of the ligands. Each polyhedron of the terbium atoms share one edge and one face of oxygen atoms with the two neighboring ones. The oxalate ligands are bischelating and bismonodentate. The coordination scheme of glutarate differs: either they are bismonodentate from one side and chelating and monodentate from the other side or they are chelating and monodentate from both sides.     

Spectroscopic and crystal structure analyses of methyl 1-phenyl-3,4-dioxo-2-naphthalenecarboxylate,C18H12O4

The crystal and molecular structure of methyl 1-phenyl-3,4-dioxo-2-naphthalenecarboxylate, C₁₈H₁₂O₄, has been determined from three-dimensional, single-crystal X-ray diffraction data. The compound crystallizes in the monoclinic space groupCc(No. 9, C _s ⁴ ) witha=9.837(2),b=16.397(3),c=8.706(1) Å,=94.88(1)°,Z=4,D _m =1.38(1) Mg m^–3, andD _x =1.388 Mg m^–3. The phasing model was determined by direct methods and the final full-matrix least-squares refinement yieldedR=0.0363 and R_w=0.0405 for 1374 unique reflections. Optical, infrared, NMR, and UV-VIS analyses have also been carried out. The molecules in the crystal lattice are held together by van der Waals forces.3-Carbomethoxy-4-phenyl-1,2-naphthoquinone.     

Crystal structure of protogenkwanin,C16H14O6

The crystal structure of protogenkwanin, C₁₆H₁₄O₆, has been determined by single-crystal diffraction methods. The compound crystallizes in the monoclinic space groupP2₁/c witha=6.804(4),b=7.457(3),c=26.234(3)Å,=95.66(2)° andZ=4. A total of 3275 unique reflection intensities were recorded on a Rigaku AFC6R diffractometer (MoK radiation) at room temperature. The structure was solved by direct methods and electron density calculations. Full-matrix least-squares refinement gaveR=0.058 for 1257 observed [I>3(I)] reflections. Thecrystal structure confirms results from earlier studies on protogenkwanin and elucidates the steric orientation of the hydroxyl substituents of the cyclohexadiene ring: the hydroxyl groups aretrans orientated.     

Crystal structure and absolute configuration of yohimbine hydrochloride,C21H27ClN2O3

Yohimbine (C₂₁H₂₆N₂O₃) is an important indole alkaloid found in the Indian snake rootrauwolfia serpentina, and is very closely related to reserpine. Yohimbine hydrochloride (C₂₁H₂₇ClN₂O₃) is orthorhombic:P2₁2₁2₁,a = 11·54,b = 24·88,c = 7·00 Å,Z = 4. X-ray diffraction data to a Bragg angle of 80 ° were collected on a G.E. diffractometer using CuK radiation. The structure was solved by direct methods, and refined to a reliability index of 9·9 % by the block-diagonal least-squares method. Yohimbine has a ring system very similar to that of reserpine, though the conformations of the ringsC andD about the C—N bond are different in the two molecules. The absolute configuration of the molecule, determined by X-ray anomalous scattering, confirms the 3, 15, 20 configuration assigned earlier by conformational analysis.     

Synthesis and crystal structure of [CuCl(phen)2]3H3V10O28 · 7 H2O

The new compound, [CuCl(phen)₂]₃H₃V₁₀O₂₈ · 7 H₂O, was prepared by reaction of an aqueous KVO₃ solution (pH 3) with an aqueous solution of CuSO₄ · 5 H₂O in which 1,10‐phenanthroline (phen) and KCl were added. The crystal structure of the compound was determined, and the proton position in H₃V₁₀O₂₈^3– were calculated by the bond length/bond number method and also determined from difference electron density map. The protons are bound to colinearly arranged μ–OV₂ and μ–OV₃ groups which is the common protonation type in trihydrogen decavanadates. The structure crystallizes in P1 space group symmetry. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal and molecular structure of 1-o-nitrophenyl-3-methyl-5-tert-butylpyrazole,C14H17N3O2

Journal of Chemical Crystallography - Crystals of 1-o-nitrophenyl-3-methyl-5-tert-butylpyrazole, C14H17N3O2, are orthorhombic:a=12.0924(6),b=11.3601(7),c=10.2317(4) Å,Z=4, space groupP212221....