scholarly journals P1 or P\bar 1? Corrigendum

2000 ◽  
Vol 56 (4) ◽  
pp. 744-744 ◽  
Author(s):  
Richard E. Marsh
Keyword(s):  
Nauk Sssr ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Acta Cryst ◽  
Triclinic Space Group ◽  
Space Group ◽  
Akad Nauk Sssr

The structure of bis((phenyl-O,N,N-azoxy)oxy)methane, C_{13}H_{12}N_4O_4, originally reported as triclinic, space group P1 [Zyuzin et al. (1997). Isz. Akad. Nauk SSSR Ser. Khim. pp. 1486–1492; CSD refcode NIXQAM] was recently revised to monoclinic, space group C2 [Marsh (1999). Acta Cryst. B55, 931–936]. It is properly described as orthorhombic, space group Fdd2.

Untersuchungen an Polyhalogeniden, XXXVI. Zur Kenntnis des Oktaiodid-Ions I82-: Darstellung und Kristallstruktur des [(Crypt-2.2.2)H2]l8, des [Ni(phen)3]I8 · 2CHCl3 und der Bis(N-alkylurotropinium) oktaiodide (UrR)2I8 mit R = Methyl und Ethyl / Studies on Polyhalides, XXXVI. On the Octaiodide Ion I82-: Preparation and Crystal Structure of [(Crypt-2.2.2)H2]I8, of [Ni(phen)3]I8-2CHCl3 and of the Bis(N-alkylurotropinium)octaiodides (UrR)2I8 with R = methyl and ethyl

1998 ◽  
Vol 53 (7) ◽  
pp. 641-652 ◽  
Author(s):  
Arista Gräfe-Kavoosian ◽  
Shida Nafepour ◽  
Klaus Nagel ◽  
Karl-Friedrich Tebbe
Keyword(s):  
Crystal Structure ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
Iodine Molecule ◽  
Orthorhombic Space Group ◽  
Triclinic Space Group ◽  
Space Group

Abstract The new compound [(Crypt-2.2.2)H2]I8 has been prepared by the reaction of [(Crypt-2.2.2)H2](I3)2 with iodine in methanol. It crystallizes in the orthorhombic space group Pbcn with a = 11.476 (2), b = 13.589 (2), c = 22.888 (2) Å and Z = 4. The crystal structure has been refined to RF = 0.031 for 1618 reflections. It may be described as a layerlike packing of octaiodide anions I82-and diprotonated 2.2.2-Crypt as cations. The non planar octaiodide anion is built up from two triiodide groups and a bridging iodine molecule.Tris(1, 10-phenanthroline)nickel(II) octaiodide bis(chloroform) crystallizes in the monoclinic space group P21/n with a = 11.683 (8), b = 21.717 (8), c = 20.752 (5) Å, β = 95.03 (5)° and Z = 4 formula units. The crystal structure has been refined to RF = 0.058 for 3894 reflections. The structure consists of two chloroform molecules, octahedrally coordinated complex cations [Ni(phen)3]2+ and nonplanar octaiodide anions I82- each composed of two asymmetric triiodide units I3- weakly associated with an elongated bridging iodine molecule I2.The already known structure of bis(N-methylurotropinium) octaiodide, (UrMe)2I8, has been verified and more accurate crystal data have been collected. The crystal structure has been refined to RF = 0.045 for 1908 reflections. The compound crystallizes in the monoclinic space group P21/c with a = 11.302 (2), b = 9.850 (2), c = 14.188 (2) Å , β = 92.59 (1)° and Z = 2. The anion has the shape of a stretched Z.The structure of bis(N-ethylurotropinium) octaiodide (UrEt)2I8 has been determined and a new configuration (I3-, I5-) for octaiodide ions between Z (I3- · I2 ·I3-) and a “broken” configuration (I3-, I5-) has been observed. The compound crystallizes in the triclinic space group P1̄ with a = 9.741 (3), b = 11.815 (3), c = 15.426 (3) Å, α = 91.80 (2), β = 107.14 (2), γ = 90.04 (2)° and Z = 2. The crystal structure has been refined to RF = 0.037 for 3657 reflections.

Three polymorphs of 3-(3-phenyl-1H-1,2,4-triazol-5-yl)-2H-1-benzopyran-2-one formed from different solvents

2019 ◽  
Vol 75 (6) ◽  
pp. 822-832 ◽  
Author(s):  
Svitlana V. Shishkina ◽  
Irina S. Konovalova ◽  
Pavlo V. Trostianko ◽  
Anna O. Geleverya ◽  
Sergiy M. Kovalenko ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Pairwise Interaction ◽  
Structural Motif ◽  
Monoclinic Space Group ◽  
Interaction Energies ◽  
Orthorhombic Space Group ◽  
Structure Packing ◽  
Triclinic Space Group ◽  
Space Group ◽  
Polymorphic Modifications

The polymorphic study of 3-(3-phenyl-1H-1,2,4-triazol-5-yl)-2H-1-benzopyran-2-one, C17H11N3O2, was performed due to its potential biological activity and revealed three polymorphic modifications in the triclinic space group P\overline{1}, the monoclinic space group P21 and the orthorhombic space group Pbca. These polymorphs have a one-column layered type of crystal organization. The strongest interactions between the molecules of the studied structures is stacking between π-systems, while N—H...N and C—H...O hydrogen bonds link stacked columns forming layers as a secondary basic structural motif. C—H...π hydrogen bonds were observed between neighbouring layers and their role is the least significant in the formation of the crystal structure. Packing differences between the polymorphic modifications are minor and can be identified only using an analysis based on a comparison of the pairwise interaction energies.

scholarly journals A variable-temperature study of a phase transition in barbituric acid dihydrate

2005 ◽  
Vol 61 (4) ◽  
pp. 464-472 ◽  
Author(s):  
Gary S. Nichol ◽  
William Clegg
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Barbituric Acid ◽  
Crystal Packing ◽  
Variable Temperature ◽  
Mirror Plane ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Acta Cryst ◽  
Space Group

The crystal structure of barbituric acid dihydrate (C4H4N2O3·2H2O) has twice been reported as orthorhombic, space group Pnma, with all atoms (except for CH2 H atoms) lying on the mirror plane [Al-Karaghouli et al. (1977). Acta Cryst. B33, 1655–1660; Jeffrey et al. (1961). Acta Cryst. 14, 881–887]. The present study has found that at low temperatures, below 200 K, the crystal structure is no longer orthorhombic but is non-merohedrally twinned monoclinic, space group P21/n. This phase is stable down to 100 K. Above 220 K the crystal structure is orthorhombic, and between 200 and 220 K the structure undergoes a phase change, with the monoclinic-to-orthorhombic phase transition itself taking place at around 216–217 K. The size of the β angle in the monoclinic structure is temperature dependent; at 100 K β is around 94° and it decreases in magnitude towards 90° as the temperature increases. Although the hydrogen-bonding motifs are the same for both crystal systems, there are significant differences in the crystal packing, in particular the out-of-plane displacement of the two water molecules and the sp 3-hybridized C atom of barbituric acid.

Kristallstrukturen der iodierten closo-Hexaborate trans-(Ph4P)2[B6H4I2], mer-(Ph4P)2[B6H3I3] · 2 CH2Cl2, trans-(Ph4P)2[B6H2I4] · 2 CH3CN und (CH2Py2)[B6HI5]/Crystal Structures of the Iodized closo-Hexaborates trans-(Ph4P)2[B6H4I2], mer-(Ph4P)2[B6H3I3] · 2 CH2Cl2, trans-(Ph4P )2[B6H2I4] · 2 CH3CN and (CH2Py2)[B6HI5]

1998 ◽  
Vol 53 (2) ◽  
pp. 206-210 ◽  
Author(s):  
D. Sonnak ◽  
W. Preetz
Keyword(s):  
Single Crystals ◽  
Crystal Structures ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Structure Determinations

Abstract X-ray structure determinations have been performed on single crystals of trans-(Ph4P)2-[B6H4I2] (1) (triclinic, space group P1̄, a = 9.9680(12), b = 10.9690(11), c = 11.0470(14) Å,α = 88.167(9), β = 80.466(12), γ = 68.839(11)°, Z = 1), mer-(Ph4P)2[B6H3I3] · 2 CH2Cl2 (2)(triclinic, space group P1̄, a = 11.8694(11), b = 15.1699(13), c = 17.051(2) Å, α = 75.118(9), β = 71.953(10), γ = 69.331(8)°, Z = 2), trans-(Ph4P )2[B6H2I4] · 2 CH3CN (3) (monoclinic, space group P21/n, a = 14.9665(10), b = 7.6783(10), c = 23.385(3) Å, β = 95.78(9)°, Z = 2), and (CH2Py2)[B6HI5] (4) (orthorhombic, space group Pnma, a = 13.660(2), b = 11.8711(13), c = 13.839(2) Å, Z = 4). The B6 octahedra are compressed in the direction of the B-I bonds, resulting in shortened diagonal B ··· B distances with average values of the groups I-B ··· B-I = 2.37 and I-B ··· B-H = 2.43 Å as compared with H-B ··· B-H = 2.49 Å.

Crystal Structures of (3S*,4S*,5S*,6S*)-3,4-Epoxy- 1,7-dioxaspiro[5.5]undecan-5-ol, (3R*,5S*,6S*)-1,7- Dioxaspiro[5.5]undecane-3,5-diyl Diacetate and (4S*,5S*,6S*)-1,7-Dioxaspiro[5.5]undecane-4,5-diol

1997 ◽  
Vol 50 (2) ◽  
pp. 123
Author(s):  
Margaret A. Brimble ◽  
Andrew Johnston ◽  
Trevor W. Hambley ◽  
Peter Turner
Keyword(s):  
Hydrogen Bonding ◽  
Hydroxy Group ◽  
Axial Position ◽  
Monoclinic Space Group ◽  
Equatorial Position ◽  
Intermolecular Hydrogen Bonding ◽  
Orthorhombic Space Group ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray Crystallography

The structures of (3S*,4S*,5S*,6S*)-3,4-epoxy-1,7-dioxaspiro[5.5]undecan-5-ol (2), (3R*,5S*,6S*)-1,7- dioxaspiro[5.5]undecane-3,5-diyl diacetate (4) and (4S*,5S*,6S*)-1,7-dioxaspiro[5.5]undecane-4,5-diol (5) have been determined by X-ray crystallography. The unsubstituted tetrahydropyran ring in (2) adopts an axial position with respect to the epoxy-substituted ring and the hydroxy group at C5 is syn to the epoxide group. Intermolecular hydrogen bonding is observed between the C5 hydroxy group and O1. The two six-membered rings in (4) adopt chair conformations and the two acetate groups adopt 1,3-diaxial positions. The C5 hydroxy group in (5) assumes an axial position anti to the C-O bond of the neighbouring ring whilst 4-OH occupies an equatorial position. Intermolecular hydrogen bonding is also observed between 4-OH and 5-OH. Compound (2), C9H14O4, M 186·21, crystallized in the monoclinic space group P 21/c with a 7·867(1), b 12·2060(9), c 9·3676(8) Å, b 102·744(8), V 877·4(1) Å 3 and No 1163 [I > 2·5s (I)], R 0·031, Rw 0·035. Compound (4), C13H20O6, M 272·30, crystallized in the triclinic space group P 1 with a 9·902(1), b 11·0024(9), c 6·9183(5)Å, a 104·078(8), b 96·769(9), g 101·980(8), V 703·8(1) Å 3 , No 1657 [I > 2·5s(I)], R 0·047, Rw 0·044. Compound (5), C9H16O4, M 188·22, crystallized in the orthorhombic space group Pbca with a 25·504(3), b 8·909(2), c 8·038(2) Å, V 1826·4(5) QA 3 , No 1096 [I > 2·5s(I)], R 0·030, Rw 0·030.

Structural Systematics of Metal Acetylide Complexes. II. X-Ray Studies of Some Nickel σ-Acetylide Complexes

1998 ◽  
Vol 51 (3) ◽  
pp. 219 ◽  
Author(s):  
Ian R. Whittall ◽  
Mark G. Humphrey ◽  
David C. R. Hockless
Keyword(s):  
Single Crystal ◽  
Least Squares ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Triclinic Space Group ◽  
Full Matrix ◽  
Space Group ◽  
X Ray ◽  
Trans Influence

The structures of Ni(C≡CR)(PPh3)(η-C5H5) (R = Ph (1), C6H4-4-NO2 (2), 4-C6H4C6H4-4′-NO2 (3), (E)-4-C6H4CH=CHC6H4-4′-NO2 (4), 4-C6H4C≡CC6H4-4′-NO2 (5), 4-C6H4N=CHC6H4-4′-NO2 (6)) have been determined by single-crystal X-ray diffraction studies, refining by full-matrix least-squares analysis. For (1), crystals are triclinic, space group P-1, with a 10·094(2), b13·429(3), c 18·835(5) Å,α 103·24(2), β 91·50(2), γ 90·10(2)°, Z 4, 5844 unique reflections (595 parameters), converging at R 0·033 and Rw 0·024. For (2), crystals are orthorhombic, space group Pna21, with a 16·799(2), b 8·681(2), c 17·485(2) Å, Z 4, 1774 unique reflections (325 parameters), converging at R 0·031 and Rw 0·029. For (3), crystals are monoclinic, space group P 21/c, with a 11·140(3), b 18·282(4), c 15·296(2) Å, β 105·18(2)°, Z 4, 3132 unique reflections (397 parameters), converging at R 0·039 and Rw 0·024. For (4), crystals are monoclinic, space group P 21/n, with a 12·929(7), b 16·953(8), c 15·601(7) Å, β 112·55(3), Z 4, 3023 unique reflections (397 parameters), converging at R 0·039 and Rw 0·025. For (5), crystals are monoclinic, space group P 21/n, with a 12·710(5), b 16·882(3), c 15·693(4) Å, β 111·37(3)°, Z 4, 3216 unique reflections (397 parameters), converging at R 0·035 and Rw 0·030. For (6), crystals are monoclinic, space group P 21/n, with a 12·594(1), b 16·936(2), c 15·611(1) Å, β 112·476(5)°, Z 4, 3564 unique reflections (397 parameters), converging at R 0·038 and Rw 0·041. For structurally characterized 18-electron (cyclopentadienyl)nickel(II) acetylide complexes, statistically insignificant decreases in the average Ni-C(1) distance and trans influence and an increase in the average C(1)-C(2) parameter are observed on introduction of an acceptor substituent at the alkynyl ligand.

Electronic and Structural Properties of the Spin Crossover Systems Bis(2,6-bis(pyrazol-3-yl)pyridine)iron(II) Thiocyanate and Selenocyanate

2000 ◽  
Vol 53 (9) ◽  
pp. 755 ◽  
Author(s):  
Kristian H. Sugiyarto ◽  
Marcia L. Scudder ◽  
Donald C. Craig ◽  
Harold A. Goodwin
Keyword(s):  
Hydrogen Bonding ◽  
High Spin ◽  
Room Temperature ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Triclinic Space Group ◽  
Space Group ◽  
Face To Face ◽  
Bright Yellow ◽  
Electronic And Structural Properties

Essentially high-spin [Fe(bpp)2][NCS]2·2H2O and [Fe(bpp)2][NCSe]2 (bpp = 2,6-bis(pyrazol-3-yl)pyridine) were isolated from an aqueous reaction mixture. Both salts undergo an abrupt transition to low spin below room temperature, that for the thiocyanate occurring in two steps and the high-spin Æ low-spin Æ high-spin cycle being accompanied by hysteresis in both steps. Recrystallization of the salts from nitromethane yielded a mixture from which bright yellow crystals were separated for structure determination. In addition, from the recrystallized selenocyanate, deep red-brown crystals of composition [Fe(bpp)2][NCSe]2·H2O·0.25 CH3NO2 were obtained. Recrystallized [Fe(bpp)2][NCS]2·2H2O and [Fe(bpp)2][NCSe]2 were identified as high spin with average Fe–N distances of 2.16 and 2.17 Å, respectively. In the unit cell of [Fe(bpp)2][NCSe]2·H2O·0.25 CH3NO2, there are four independent iron atoms, three identified as low spin and the fourth as high spin. All salts crystallize in a layer-type array involving edge-to-face and face-to-face aryl–aryl-type interactions. Hydrogen bonding between pyrazole >NH groups, anions and solvate molecules is observed. The structure of the uncoordinated ligand was also determined, the molecule being found in a planar arrangement with thecis–cis configuration for the pyrazolyl groups relative to the central pyridyl and the >NH group being at the N 2 atom. Hydrogen bonding involving the >NH groups leads to stepped stacks of molecules. The principal difference in the geometry of coordinated and free bpp molecules is a contraction in the angles about the interannular bridges in the chelate rings. [Fe(bpp)2][NCS]2·2H2O: triclinic, space group P1–, a 8.302(6), b 8.446(6), c 21.531(13) Å, a 78.78(5), b 82.80(5), g 89.85(4)˚, Z 2. [Fe(bpp)2][NCSe]2: triclinic, space group P1–, a 8.354(4), b 8.409(4), c 19.918(9) Å, a 87.02(3), b 83.15(3), g 88.86(3)˚, Z 2. [Fe(bpp)2][NCSe]2·H2O·0.25 CH3NO2: monoclinic, space group Pn, a 16.425(12), b 20.774(9), c 16.933(14) Å, b 90.91(4)˚, Z 8. Uncoordinated bpp: orthorhombic, space group Pna21, a 8.075(3), b 22.479(9), c 5.525(1) Å, b Z 4.

X-ray structures of adducts of 1,2,5-triphenylphosphole with dimethyl acetylenedicarboxylate: a confirmation, a revision, and a new structure

1993 ◽  
Vol 71 (11) ◽  
pp. 1873-1889 ◽  
Author(s):  
Martin B. Hocking ◽  
Francies W. Van Der Voort Maarschalk
Keyword(s):  
Amorphous Material ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Dimethyl Acetylenedicarboxylate ◽  
Orthorhombic Space Group ◽  
Polymeric Product ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Cell Refinement

Dimethyl acetylenedicarboxylate was reacted with 1,2,5-triphenylphosphole under mild conditions, and four products isolated. Regardless of conditions used, every preparation gave low yields of dimethyl 3,6-diphenylphthalate coincident with loss of the phosphorus bridge. NMR data and X-ray crystal structures are provided for a yellow, and a red, 2:1 adduct. The yellow adduct, tetramethyl 1,6,7-triphenyl-6-phospha(V)-tricyclo[7.3.1.01,9]nona-3,5,7-triene-2,3,4,5-tetracarboxylate 6, crystallized in the triclinic space group [Formula: see text] (No. 2) with two molecules in the unit cell. Refinement (a = 11.259(1) Å, b = 12.947(3) Å, c = 13.784(3) Å, α = 112.25(2)°, β = 103.44(1)°, and γ = 101.80(1)°) converged at R = 0.0453 (Rw = 0.0453) for 537 parameters using 2880 reflections with I > 2σ(I). The red adduct, trimethyl 1,2,5-triphenylphosphoranylidene-4-methoxycyclopent-2-ene-5-one-2,3,4-tricarboxylate, an exocyclic phosphorane 8, crystallized in the monoclinic space group P21/c (No. 14) with four molecules in the unit cell. Refinement of this structure (a = 13.233(5) Å, b = 15.712(5) Å, c = 17.191(7) Å, α = 90°, β = 110.35(4)°, and γ = 90°) converged at R = 0.0916 (Rw = 0.0937) for 400 parameters using 2052 reflections with I > 2.5σ(I). Small amounts of a white or buff amorphous material, which could represent a polymeric product from the lost phosphorus bridge, were also obtained. Thermal rearrangement of the yellow adduct gave a colourless 6,5,3 tricyclic isomer 11, possibly via the isomeric cyclopropyl derivative 15 or the nine-membered phosphonin 7. The structure of 11 was confirmed by mild oxidation of the colourless rearrangement product to its P-oxide. This product, tetramethyl 2,3,6-triphenyl-2-phosphatricyclo[6.1.01,8.05,9]-2-oxonona-3,6-diene-1,7,8,9-tetracarboxylate 12, was also colourless. It crystallized in the orthorhombic space group Pbc21 (No. 29) with four pairs of molecules in the unit cell. Refinement of this structure (a = 8.918(1) Å, b = 22.605(4) Å, and c = 30.169(6) Å) converged at R = 0.0747 (Rw = 0.0757) for 321 parameters using 3255 reflections with I > 3σ(I). Unequivocal structures for these adducts and derivatives finally confirms, and establishes further understanding of, the complex reactions of the triphenylphosphole with dimethyl acetylenedicarboxylate.

scholarly journals A third polymorph of 1,4-bis(1H-benzimidazol-2-yl)benzene

2014 ◽  
Vol 70 (6) ◽  
pp. o699-o699
Author(s):  
Wei-Wei Fu ◽  
Yan-Fei Liang ◽  
Yang Liu ◽  
Xiao-Ming Zhu
Keyword(s):  
Hydrogen Bonds ◽  
The Other ◽  
Monoclinic Space Group ◽  
Benzimidazole Ring ◽  
Asymmetric Unit ◽  
Orthorhombic Space Group ◽  
Acta Cryst ◽  
Space Group ◽  
Compound C ◽  
Independent Molecules

The title compound, C20H14N4, is a new polymorph of the previously reported structures, which were orthorhombic, space groupPbca[Beiet al.(2000).Acta Cryst.C56, 718–719] and monoclinic, space groupP21/c[Duddet al.(2003).Green Chem.5, 187–192]. The asymmetric unit consists of two independent molecules in which the dihedral angels between the central benzene ring and the outer benzimidazole ring systems are 16.81 (10) and 14.23 (10)° in one molecule and 26.09 (10) and 37.29 (10)° in the other. In the crystal, molecules are linked by N—H...N and C—H...N hydrogen bonds into a tape running along thec-axis direction.

Structures of 2,6-disubstituted naphthalenes

1999 ◽  
Vol 55 (1) ◽  
pp. 85-94 ◽  
Author(s):  
James A. Kaduk ◽  
Joseph T. Golab
Keyword(s):  
Crystal Structures ◽  
Ester Group ◽  
Carboxyl Groups ◽  
Monoclinic Space Group ◽  
Ring Plane ◽  
Orthorhombic Space Group ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
The Mean

The crystal structures of 2,6-naphthalenedicarboxylic acid (NDA) and dimethyl 2,6-naphthalenedicarboxylate (NDC) have been solved ab initio using a combination of X-ray powder diffraction and computational chemistry techniques. These two crystal structures, and that of 2,6-dimethylnaphthalene (DMN), have been refined by the Rietveld technique. DMN crystallizes in the orthorhombic space group Pbca, with a = 7.4544 (4), b = 6.0826 (6), c = 20.0946 (12) Å, V = 911.1 (1) Å3 and Z = 4. The structure consists of a herringbone stacking parallel to a, resulting in loosely bound layers perpendicular to c. NDA crystallizes in the triclinic space group P1¯, with a = 3.7061 (8), b = 7.4688 (14), c = 8.5352 (22) Å, α = 86.62 (2), β = 85.49 (2), γ = 87.99 (2)°, V = 235.00 (6) Å3 and Z = 1. The structure consists of loosely packed hydrogen-bonded chains along [11¯1]. NDC crystallizes in the monoclinic space group P21/c, with a = 13.41931 (14), b = 6.14869 (5), c = 7.15257 (5) Å, β = 100.400 (1)°, V = 580.47 (1) Å3 at 300 K and Z = 2. The structure consists of layers of NDC molecules perpendicular to a. The ester group is twisted 20° out of the mean ring plane in NDC. The conformations of the carboxyl groups in NDA and NDC differ. MP2 calculations suggest that the observed twist in NDC corresponds to an increase in conformational energy of 9 kJ mol−1.

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