The crystal structure of 4,7-oxido-7-methyl-7-hydroxymethyl-2,2,6,6-tetramethylpiperidin-1-oxyl

1982 ◽  
Vol 60 (18) ◽  
pp. 2392-2397 ◽  
Author(s):  
M. Cygler
Keyword(s):  
Direct Methods ◽  
Chair Conformation ◽  
Hydroxyl Group ◽  
Piperidine Ring ◽  
Monoclinic Space Group ◽  
Intensity Data ◽  
Asymmetric Unit ◽  
Torsion Angles ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

4,7-Oxido-7-methyl-7-hydroxymethyl-2,2,6,6-tetramethylpiperidin-1-oxyl, C12H22NO3, crystallizes in the monoclinic space group P21/m with unit cell dimensions a = 8.041(1), b = 13.348(1), c = 5.945(1) Å, β = 95.90(1)°, Z = 2. Intensity data were measured on a diffractometer and the structure solved by direct methods. The least-squares refinement converged at R = 0.039 for 1304 reflections. Two enantiomeric molecules, differing in the position of the OH group, occupy the same site in the asymmetric unit (each with a probability of 0.5) giving rise to a disorder of the hydroxyl group. The piperidine ring adopts the usual chair conformation, with C—C—C—C torsion angles being intermediate between those observed for C(4) mono- and for bisubstituted nitroxypiperidine derivatives. The N—O bond is 1.282(2) Å long, and it makes an angle of 18.5(2)° with the CNC plane. Molecules are connected by O—H … O hydrogen bonds. The influence of the degree of substitution at C(4) on ring geometry is discussed.

Solid state and solution conformations of 1 -(β-D-2′,3′-secoribofuranosyl)-5,6-dichlorobenzimidazole, an acyclonucleoside analogue

1985 ◽  
Vol 63 (6) ◽  
pp. 1215-1221 ◽  
Author(s):  
George I. Birnbaum ◽  
Ryszard Stolarski ◽  
Zygmunt Kazimierczuk ◽  
David Shugar
Keyword(s):  
Direct Methods ◽  
Monoclinic Space Group ◽  
Intensity Data ◽  
Asymmetric Unit ◽  
X Ray ◽  
H Nmr ◽  
Cell Dimensions ◽  
Independent Molecules ◽  
Unit Cell Dimensions ◽  
Glycosidic Torsion Angle

The title compound crystallizes in the monoclinic space group P21, with two independent molecules in the asymmetric unit (Z = 4). The unit cell dimensions are a = 11.861(2), b = 7.897(1), c = 14.527(3) Å, β = 91.28(1)°. X-ray intensity data were measured on a diffractometer, and the crystal structure was determined by direct methods. Least-squares refinement converged at R = 0.036 for 2980 reflections. The glycosidic torsion angle [C(2)—N(1)—C(1′)—O(1′)] is 53.9° in molecule A and 129.8° in molecule B. In both molecules, the orientation of C(1′)—O(1′) to C(2′)—O(2′) is trans. The conformations about C(3′)—C(4′) and C(4′)—C(5′) are different in each of the two molecules. These features are compared with those of acyclonucleoside analogues with antiviral activity. The conformation in aqueous medium was examined with the aid of high-resolution 1H nmr spectroscopy, and the results are compared with those obtained from the X-ray analysis.

The Molecular Conformation of 1e,2a,6e-Trimethyl-4e-phenyl-4a-acetoxypiperidine Hydrobomide in the Crystalline State

1973 ◽  
Vol 51 (10) ◽  
pp. 1535-1542 ◽  
Author(s):  
K. Hayakawa ◽  
M. N. G. James
Keyword(s):  
Molecular Conformation ◽  
Heavy Atom ◽  
Chair Conformation ◽  
Piperidine Ring ◽  
Monoclinic Space Group ◽  
Narcotic Analgesics ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Heavy Atom Method ◽  
The Ideal

The title compound represents one analog of the synthetic 4-phenylpiperidine narcotic analgesics. The crystal structure was determined by the heavy-atom method from data collected on an automated diffractometer. The crystals are monoclinic, space group P21/c, with unit cell dimensions a = 11.833 Å, b = 11.551 Å, c = 14.659 Å and β = 121° 9′. The final residual, R, was 0.056. The stereochemistry of the substituents on the piperidine ring as deduced by this structural determination (1e,2a,6e-trimethyl-4e-phenyl-4a-acetoxypiperidine) confirms the p.m.r. results on the alcohol precursor as trans 2-Me/6-Me and trans 2-Me/4-Ph. There is a normal length N—H … Br hydrogen bond of 3.234 Å; most intramolecular bond lengths and angles are within the expected ranges but some distortion of the ideal chair conformation of the piperidine ring occurs.

The crystal structure of sarmientite, Fe23+ (AsO4)(SO4)(OH)·5H2O, solved ab initio from laboratory powder diffraction data

2014 ◽  
Vol 78 (2) ◽  
pp. 347-360 ◽  
Author(s):  
F. Colombo ◽  
J. Rius ◽  
O. Vallcorba ◽  
E. V. Pannunzio Miner
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Direct Methods ◽  
Hydroxyl Group ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
Patterson Function ◽  
Unit Cell Dimensions

AbstractThe crystal structure of sarmientite, Fe23+ (AsO4)(SO4)(OH)·5H2O, from the type locality (Santa Elena mine, San Juan Province, Argentina), was solved and refined from in-house powder diffraction data (CuKα1,2 radiation). It is monoclinic, space group P21/n, with unit-cell dimensions a = 6.5298(1), b = 18.5228(4), c = 9.6344(3) Å, β = 97.444(2)º, V = 1155.5(5) Å3, and Z = 4. The structure model was derived from cluster-based Patterson-function direct methods and refined by means of the Rietveld method to Rwp = 0.0733 (X2 = 2.20). The structure consists of pairs of octahedral-tetrahedral (Fe−As) chains at (y,z) = (0,0) and (½,½), running along a. There are two symmetry-independent octahedral Fe sites. The Fe1 octahedra share two corners with the neighbouring arsenate groups. Both individual chains are related by a symmetry centre and joined by two symmetry-related Fe2 octahedra. Each Fe2 octahedron shares three corners with double-chain polyhedra (O3, O4 with arsenate groups; the O8 hydroxyl group with the Fe1 octahedron) and one corner (O11) with the monodentate sulfate group. The coordination of the Fe2 octahedron is completed by two H2O molecules (O9 and O10). There is also a complex network of H bonds that connects polyhedra within and among chains. Raman and infrared spectra show that (SO4)2− tetrahedra are strongly distorted.

scholarly journals The reaction of 3,5-diphenyl-1,2-dithiolium-4-olate with aniline: the crystal structure of 1-phenylimino-2-phenylamino-3-phenylindene

1987 ◽  
Vol 65 (12) ◽  
pp. 2830-2833 ◽  
Author(s):  
David M. McKinnon ◽  
Peter D. Clark ◽  
Robert O. Martin ◽  
Louis T. J. Delbaere ◽  
J. Wilson Quail
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

3,5-Diphenyl-1,2-dithiolium-4-olate (1) reacts with aniline to form 1-phenylimino-2-phenylamino-3-phenylindene (3a). Under suitable conditions, 6-phenylbenzo[b]indeno[1,2-e]-1,2-thiazine is also formed. These structures are confirmed by alternative syntheses. The molecular structure of 3a has been determined by single crystal X-ray diffraction. Compound 3a crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 20.777(3) Å, b = 6.130(3) Å, c = 31.327(3) Å, 3 = 99.59(1)°, and Z = 8. The structure was solved by direct methods and refined by least squares to a final R = 0.055. The molecular structure of 3a shows the three phenyl containing substituents to have the planes of their ring systems tilted between 40° and 60° from the plane of the indene system due to steric repulsions.

Conformational features of acyclonucleosides: structure of acyclovir, an antiherpes agent

1984 ◽  
Vol 62 (12) ◽  
pp. 2646-2652 ◽  
Author(s):  
George I. Birnbaum ◽  
Miroslaw Cygler ◽  
David Shugar
Keyword(s):  
Direct Methods ◽  
Side Chain ◽  
Asymmetric Unit ◽  
Hydrogen Atoms ◽  
Torsion Angles ◽  
The Third ◽  
Cell Dimensions ◽  
Enzymatic Systems ◽  
Antiviral Activities ◽  
Independent Molecules

Crystals of acyclovir belong to the space group P21/n, and the cell dimensions are a = 25.459(1), b = 11.282 (1), c = 10.768(1) Å, β = 95.16(1)°. Intensity data were measured on a diffractometer and the structure was determined by direct methods. The asymmetric unit was found to contain three independent molecules of acyclovir and two molecules of water. Least-squares refinement, which included all hydrogen atoms, converged at R = 0.053 for 3970 observed reflections. In two of the molecules the side chain is partially folded, while in the third one it is fully extended. The glycosidic torsion angles are in the range 91.4–104.3°. The conformational features are compared with those in other known acyclonucleosides. They are also examined in relation to the behavior of acyclonucleosides and acyclonucleotides in various enzymatic systems, including those related to antiviral activities.

Conformation of azaphosphorinane ring. Crystal structures of 2,2,6,6-tetramethyl-4,4-diphenyl-1,4-azaphosphorinanium perchlorate and 2,2,6,6-tetramethyl-4-oxo-4-phenyl-1,4-azaphosphorinan-1-oxyl (stable nitroxy radical)

1983 ◽  
Vol 61 (3) ◽  
pp. 427-433 ◽  
Author(s):  
Miroslaw Cygler ◽  
Janusz Skolimowski
Keyword(s):  
Crystal Structures ◽  
Heavy Atom ◽  
Phenyl Group ◽  
Direct Methods ◽  
Chair Conformation ◽  
Monoclinic Space Group ◽  
Compound I ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Unit Cell Dimensions

Crystal structures of 2,2,6,6-tetramethyl-4,4-diphenyl-1,4-azaphosphorinanium perchlorate (I) and 2,2,6,6-tetramethyl-4-oxo-4-phenyl-1,4-azaphosphorinan-1-oxyl (II) were determined. Compound I crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 18.2967(7), b = 10.9413(6), c = 20.8714(13) Å, β = 90.79(1)° (at 115 K), and II crystallizes in the orthorhombic space group Pn21a with a = 8.076(1), b = 10.139(1), c = 17.894(1) Å. Intensity data were measured on a diffractometer at 115 K for I and at the room temperature for II. The structures were solved by a combination of heavy-atom and direct methods and refined to R = 0.036 (3968 reflections) for I and 0.039 (1451 reflections) for II.The azaphosphorinane ring adopts a chair conformation in both molecules, being flattened in the P part in I and in the N part in II. In molecule I the equatorial phenyl group is nearly parallel to the approximate plane of symmetry of the molecule, and the axial phenyl group is perpendicular to that plane. In molecule II the P=O bond is axial and the phenyl group is equatorial. The CN(O)C group is not planar. The N—O bond makes an angle of 18.0(3)° with the CNC plane. The CNC angle of 129.3(3)° is larger than that found in nitroxypiperidine analogues.

Crystal Structures and Thermal Behavior of Isostructural Bis(dibenzyldimethylammonium) Tetrachlorometallate [M = Mn(II), Co(II), Ni(II) and Zn(II)] Solvates Crystallized from Acetonitrile and/or Methanol Solutions

2007 ◽  
Vol 62 (1) ◽  
pp. 28-34 ◽  
Author(s):  
Sara Busi ◽  
Roland Fröhlich ◽  
Manu Lahtinen ◽  
Jussi Valkonen ◽  
Kari Rissanen
Keyword(s):  
Crystal Structures ◽  
Solvent Molecule ◽  
Monoclinic Space Group ◽  
Asymmetric Unit ◽  
Π Interactions ◽  
Copper Compounds ◽  
Methanol Solutions ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Weak Edge

Five isostructural bis(dibenzyldimethylammonium) tetrachlorometallate solvate complexes [M = Mn(II), Co(II), Ni(II) or Zn(II)] were crystallized from acetonitrile and/or methanol solutions. The crystal structures are compared to those of the analogous, isostructural copper compounds (X = Cl or Br) reported earlier. The complexes crystallize in the monoclinic space group P21/n with Z = 4, and unit cell dimensions of a ≈ 14.1, b ≈ 16.1, c ≈ 15.7 °A and β ≈ 108 - 109°. The asymmetric unit of these compounds contains one MCl42− anion, two Bz2Me2N+ cations in theW-conformation and one half of a disordered solvent molecule (acetonitrile or methanol). The geometry of the MCl42− anion is close to tetrahedral, whereas the analogous copper anions appeared in distorted tetrahedral geometries with trans angles of 124.4° for X = Cl and 123.6° for X = Br. In addition to the ionic interactions between the cations and the anions, the components are connected by weak C-H· · · Cl− bonds. As a distinction between the two crystallographically independent cations in the asymmetric unit, one type of independent cations form long chains via weak edge to face π-π interactions along the crystallographic b axis, whereas the other type of cations are not tied together by such weak π-π interactions. The coordination around the N atoms is also nearly tetrahedral, and neither static nor dynamic disorder of the Bz2Me2N+ cations can be observed. The complexes are thermally stable and melt close to the decomposition temperatures in the range 170 - 205 °C.

Solid State and Solution Structures of an Adenine Analogue of the Antiviral Acyclonucleoside 9-(1,3-Dihydroxy-2-propoxymethyl)guanine

1990 ◽  
Vol 45 (7-8) ◽  
pp. 915-921 ◽  
Author(s):  
Joachim Granzin ◽  
Wolfram Saenger
Keyword(s):  
Solid State ◽  
Biological Activities ◽  
Monoclinic Space Group ◽  
Asymmetric Unit ◽  
Extended Form ◽  
Solution Structures ◽  
Cell Dimensions ◽  
Independent Molecules ◽  
Unit Cell Dimensions ◽  
C Nmr

Abstract The title compound. 9-(1,3-dihydroxy-2-propoxymethyl)adenine (DHP-Ade). an analogue of the antiviral acyclonucleoside 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG), crystallizes in the monoclinic space group P21. with unit cell dimensions of a = 10.848(4), b = 8.765(3), c = 11.432(4) Å. β = 102.14(3)° . with two independent molecules in the asymmetric unit. The crystal structure of DHP-Ade was determined and compared with that for DHPG. The solution conformations of both acyclonucleosides were also determined with the aid of 1H and ,13C NMR spectroscopy. In the solid state the acyclic chain may adopt a “folded” form, i.e. gauche about the C(1′)-O(1′) bond (as in DHP-Ade), or an “extended” form (as in DHPG), results which corre- spond to the rotations about this bond in solution. A general discussion is presented of the conformations of the acyclic chains of various acyclonucleosides, from the antiviral 9-(2-hydroxyethoxymethyl)guanine (Acyclovir, ACV) through to 2′,3′-seco-nucleosides, both in the solid state and in solution, and the relevance of these to biological activities.

Crystal and Molecular Structure of the Synthetic Intermediate, 2-Bromo-3-methoxy-5-hydroxy-5,6,7,8,9,10,13,14-octahydro-8-methyl-10,13-N-acetylaminomethano-phenanthrene, C19H24O3NBr

1973 ◽  
Vol 51 (16) ◽  
pp. 2637-2638 ◽  
Author(s):  
H. Lynton ◽  
P. Y. Siew
Keyword(s):  
Crystal And Molecular Structure ◽  
Heavy Atom ◽  
Monoclinic Space Group ◽  
Asymmetric Unit ◽  
Full Matrix ◽  
Cell Dimensions ◽  
Ring Nitrogen ◽  
Unit Cell Dimensions ◽  
Synthetic Intermediate ◽  
Heavy Atom Method

Crystals of the synthetic intermediate, 2-bromo-3-methoxy-5-hydroxy-5,6,7,8,9,10,13,14-octahydro-8-methyl-10,13-N-acetyl aminomethano-phenanthrene, C19H24O3NBr, are monoclinic, space group P21/n, unit cell dimensions a = 10.62(1), b = 14.47(2), c = 23.88(2) Å, β = 99.4(2)°, z = 8 with two molecules in the asymmetric unit. The structure was solved by the heavy atom method and refined by full matrix least squares to R = 0.096 for 2120 observed reflections. The conformation was found to be cis at the junction between rings A and B making further cyclization to obtain an A ring nitrogen bridge not possible.

Structure and conformation of 2′,5′-anhydroarabinosylcytosine: X-ray, 1H nmr and 13C nmr analyses

1987 ◽  
Vol 65 (2) ◽  
pp. 271-276 ◽  
Author(s):  
George I. Birnbaum ◽  
Miloš Buděšínský ◽  
Jiří Berànek
Keyword(s):  
Direct Methods ◽  
Coupling Constants ◽  
Monoclinic Space Group ◽  
Hydrogen Atoms ◽  
Solution Conformation ◽  
Torsion Angles ◽  
X Ray ◽  
Bicyclic System ◽  
Anti Conformation ◽  
Cell Dimensions

Crystals of 2′,5′-anhydroarabinosylcytosine hemihydrate belong to the monoclinic space group P21. The cell dimensions are a = 9.643(2), b = 10.328(1), c = 10.544(2) Å, β = 94.55(1)°. X-ray intensity data were measured on a diffractometer and the structure was determined by direct methods. Least-squares refinement, which included all nucleoside hydrogen atoms, converged at R = 0.041 for 2298 observed reflections. The asymmetric unit contains two molecules of the nucleoside and one molecule of water. In both nucleoside molecules, the conformation about the glycosyl bond is and, with XCN values of 15.5(3) and 26.3(3)°, respectively. In the bicyclic sugar moiety, the arabinofuranose rings adopt a C(3′)exo/C(2′)endo conformation and are highly puckered (τm = 57°). The solution conformation was studied by 1H and 13C nmr spectroscopy. A difference nOe proton nmr spectrum and 3J(C,H) coupling constants reveal an anti conformation in solution, with torsion angles very similar to those obtained from X-ray analysis. A comparison of observed 3J(H,H) coupling constants with those calculated on the basis of a modified Karplus equation shows significant differences, probably due to the presence of the bicyclic system.

Sign in / Sign up

Export Citation Format

Share Document