Different forms of antiparallel stacking of hydrogen-bonded antidromic rings in the solid state: polymorphism with virtually the same unit cell and two-dimensional isostructurality with alternating layers

2004 ◽  
Vol 60 (6) ◽  
pp. 755-762 ◽  
Author(s):  
Alajos Kálmán ◽  
László Fábián ◽  
Gyula Argay ◽  
Gábor Bernáth ◽  
Zsuzsanna Cs. Gyarmati

As a continuation of a systematic structural analysis of 2-hydroxycycloalkanecarboxylic acids and their carboxamide analogs, the effects of antidromic rings [Jeffrey & Saenger (1991). Hydrogen Bonding in Biological Structures. Berlin, Heidelberg: Springer Verlag] upon the layer stacking of cyclopentane and cycloheptane derivatives are compared. Determination of the structure of trans-2-hydroxycycloheptanecarboxylic acid (2) led to the discovery of two polymorphs with virtually the same unit cell [Kálmán et al. (2003). J. Am. Chem. Soc. 125, 34–35]. (i) The layer stacking of the antidromic rings for the whole single crystal is antiparallel (2b). (ii) The antidromic rings and the 21 axis are parallel (2a), consequently the domains of the single crystal must be antiparallel. While their polymorphism is solvent-controlled, they illustrate a novel form of two-dimensional isostructurality. Antiparallel layer stacking is again demonstrated by trans-2-hydroxycycloheptanecarboxamide (3) (space group Pbca). It is built up from layers isostructural with those in the homologous trans-2-hydroxycyclopentanecarboxamide (4) [Kálmán et al. (2001). Acta Cryst. B57, 539–550], but in this structure (space group Pca21) the layers are stacked in parallel mode. Similar to (2a) and (2b), the antiparallel layer stacking in (3) versus their parallel array in (4) illustrates the two-dimensional isostructurality with alternating layer orientations. Although (3) and (4) display isostructurality, they are not isomorphous.

1995 ◽  
Vol 50 (4) ◽  
pp. 699-701 ◽  
Author(s):  
Norbert W. Mitzel ◽  
Jürgen Riede ◽  
Klaus Angermaier ◽  
Hubert Schmidbaur

The solid-state structure of N,N-dibenzylhydroxylamine (1) has been determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P 21/n with four formula units in the unit cell. N,N-dibenzylhydroxylamine dimerizes to give N2O2H2 sixmembered rings as a result of the formation of two hydrogen bonds O - H ··· N in the solid state.


IUCrJ ◽  
2015 ◽  
Vol 2 (5) ◽  
pp. 523-533 ◽  
Author(s):  
Mousumi Garai ◽  
Kumar Biradha

The homologous series of phenyl and pyridyl substituted bis(acrylamido)alkanes have been synthesized with the aim of systematic analysis of their crystal structures and their solid-state [2 + 2] reactivities. The changes in the crystal structures with respect to a small change in the molecular structure, that is by varying alkyl spacers between acrylamides and/or by varying the end groups (phenyl, 2-pyridyl, 3-pyridyl, 4-pyridyl) on the C-terminal of the amide, were analyzed in terms of hydrogen-bonding interference (N—H...NpyversusN—H...O=C) and network geometries. In this series, a greater tendency towards the formation of N—H...O hydrogen bonds (β-sheets and two-dimensional networks) over N—H...N hydrogen bonds was observed. Among all the structures seven structures were found to have the required alignments of double bonds for the [2 + 2] reaction such that the formations of single dimer, double dimer and polymer are facilitated. However, only four structures were found to exhibit such a solid-state [2 + 2] reaction to form a single dimer and polymers. The two-dimensional hydrogen-bonding layerviaN—H...O hydrogen bonds was found to promote solid-state [2 + 2] photo-polymerization in a single-crystal-to-single-crystal manner. Such two-dimensional layers were encountered only when the spacer between acryl amide moieties is butyl. Only four out of the 16 derivatives were found to form hydrates, two each from 2-pyridyl and 4-pyridyl derivatives. The water molecules in these structures govern the hydrogen-bonding networks by the formation of an octameric water cluster and one-dimensional zigzag water chains. The trends in the melting points and densities were also analyzed.


1995 ◽  
Vol 28 (5) ◽  
pp. 599-603 ◽  
Author(s):  
Y. Kanke ◽  
H. Shigematsu ◽  
K. Ohshima ◽  
K. Kato

The unit cell and space group of orthorhombic NaV6O11 (low-temperature form) are found by an X-ray single-crystal diffraction study at 300 K (hexagonal, P63/mmc), 100 K (hexagonal, P63 mc) and 20 K (orthorhombic). The orthorhombic form (o) shows no superstructure and its unit cell is related to the hexagonal one (h): a o ≃ a h + b h , a o ≃ −a h + b h and c o ≃ c h . Bijvoet-pair examination confirms that it crystallizes in the noncentrosymmetric space group Cmc21. The hexagonal (P63 mc)-orthorhombic (Cmc21) structural phase transition is proved to be of second order.


1995 ◽  
Vol 48 (7) ◽  
pp. 1373 ◽  
Author(s):  
AT Baker ◽  
DC Craig ◽  
AD Rae

The crystal structure of bis (2,2′:6′,2″-terpyridine)nickel(II) bis (perchlorate) hydrate has been determined by single-crystal X-ray diffractometry . The compound is monoclinic, space group P21, with two molecules in a unit cell of dimensions a 8.827(4), b 8.910(2), c 20.148(9) Ǻ, β 98.71(2)°. The structure was refined by least-squares to a residual of 0.065 for 2184 observed reflections. The compound is found to be isomorphic with the iron(II) analogue previously reported: the cation has approximate D2d symmetry, with the main distortion from octahedral symmetry being an axial compression. Both the solid state reflectance and solution spectra have been measured and some significant differences are noted.


IUCrData ◽  
2021 ◽  
Vol 6 (3) ◽  
Author(s):  
Carly R. Reed ◽  
Robert N. Garner ◽  
William W. Brennessel

The title compound, [Ru(C5H6N2)(C10H8N2)(C15H11N3)](PF6)2 solvent, crystallizes in the triclinic space group P\overline{1} with one dicationic Ru complex, two PF6 − anions, and undefined solvent in the asymmetric unit. The cation and anions are linked via N—H...F hydrogen bonding. One PF6 − anion is disordered over two positions, with occupancies 0.634 (8) and 0.366 (8). The solvent, which is located in channels in the crystal, is highly disordered. Reflection contributions from the solvent were added to the calculated structure factors using the SQUEEZE routine [Spek (2015) Acta Cryst. C71, 9–18] of the program PLATON, which determined there to be 59 electrons in 264 Å3 treated this way per unit cell. Because the exact identity and amount of solvent were unknown, no solvent was included in the atom list or molecular formula.


1995 ◽  
Vol 10 (1) ◽  
pp. 2-6 ◽  
Author(s):  
N. R. Khasanova ◽  
A. V. Mironov ◽  
E. V. Antipov

The incommensurately modulated structure of Bi2Sr2Eu1.3Ce0.7Cu2O10.17, with a = 5.4752(4) Å, b = 5.4522(3) Å, c = 17.860(1) Å, Z = 2, was refined by the GJANA program [Gao et al., Acta Cryst. A 49, 141 (1993)] from X-ray powder data in C:C2mb: 111 four-dimensional space group (Rov = 0.064, Rm = 0.041, Rsat = 0.202, Rp = 0.049, Rwp = 0.065). Displacive modulation parameters of all cations and oxygen atoms in the Bi-layer were involved in the refinement. Obtained results including the modulation parameters are in agreement with those found for the similar phase Bi2Sr1.7Nd1.8Ce0.5Cu2O10+δ from single-crystal data [Mironov et al., J. Solid State Chem. 109, 74 (1994)].


1988 ◽  
Vol 66 (1) ◽  
pp. 123-131 ◽  
Author(s):  
William O. Nelson ◽  
Timothy B. Karpishin ◽  
Steven J. Rettig ◽  
Chris Orvig

A series of 3-hydroxy-2-methyl-4(1H)-pyridinones has been prepared with the substituents H, CH3, n-C6H11, and CH2CH2NH2 at the ring N. The dipyridinone 1,6-bis(3-hydroxy-2-methyl-4(1H)-pyridinon-1-yl)hexane has also been synthesized. The products with H and CH3 substituents have been studied by single crystal X-ray diffraction. Crystals of 3-hydroxy-2-methyl-4-pyridinone are monoclinic, a = 6.8351(4), b = 10.2249(4), c = 8.6525(4) Å, β = 105.215(4)°, Z = 4, space group P21/n and those of 3-hydroxy-1,2-dimethyl-4-pyridinone are orthorhombic, a = 7.3036(4), b = 13.0490(6), c = 13.7681(7) Å, Z = 8, space group Pbca. Both structures were solved by direct methods and were refined by full-matrix least-squares procedures to R = 0.037 and 0.044 for 914 and 857 reflections with I ≥ 3σ(I), respectively. Bond lengths and angles in the two compounds were normal. All the compounds have been studied by mass spectrometry, and by infrared and proton nmr spectroscopies. The importance of hydrogen bonding to both the solution and solid state properties of these compounds has been confirmed by these techniques.


2015 ◽  
Vol 70 (3) ◽  
pp. 191-196 ◽  
Author(s):  
Olaf Reckeweg ◽  
Francis J. DiSalvo

AbstractThe new compounds LiK[C(CN)3]2 and Li[C(CN)3]·½ (H3C)2CO were synthesized and their crystal structures were determined. Li[C(CN)3]·½ (H3C)2CO crystallizes in the orthorhombic space group Ima2 (no. 46) with the cell parameters a=794.97(14), b=1165.1(2) and c=1485.4(3) pm, while LiK[C(CN)3]2 adopts the monoclinic space group P21/c (no. 14) with the cell parameters a=1265.7(2), b=1068.0(2) and c=778.36(12) pm and the angle β=95.775(7)°. Single crystals of K[C(CN)3] were also acquired, and the crystal structure was refined more precisely than before corroborating earlier results.


Author(s):  
Alejandro Hernandez ◽  
Indranil Chakraborty ◽  
Gabriela Ortega ◽  
Christopher J. Dares

The title compound, [UO2(acac)2(H2O)] consists of a uranyl(VI) unit ([O=U=O]2+) coordinated to two monoanionic acetylacetonate (acac, C5H7O2) ligands and one water molecule. The asymmetric unit includes a one-half of a uranium atom, one oxido ion, one-half of a water molecule and one acac ligand. The coordination about the uranium atom is distorted pentagonal–bipyramidal. The acac ligands and Ow atom comprise the equatorial plane, while the uranyl O atoms occupy the axial positions. Intermolecular hydrogen bonding between complexes results in the formation of two-dimensional hexagonal void channels along the c-axis direction with a diameter of 6.7 Å. The monoclinic (P21/c space group) polymorph was reported by Alcock & Flanders [(1987). Acta Cryst. C43, 1480–1483].


2020 ◽  
Vol 84 (5) ◽  
pp. 699-704
Author(s):  
Luca Bindi ◽  
Andrew C. Roberts ◽  
Cristian Biagioni

AbstractAlstonite, BaCa(CO3)2, is a mineral described almost two centuries ago. It is widespread in Nature and forms magnificent cm-sized crystals. Notwithstanding, its crystal structure was still unknown. Here, we report the crystal-structure determination of the mineral and discuss it in relationship to other polymorphs of BaCa(CO3)2. Alstonite is trigonal, space group P31m, with unit-cell parameters a = 17.4360(6), c = 6.1295(2) Å, V = 1613.80(9) Å3 and Z = 12. The crystal structure was solved and refined to R1 = 0.0727 on the basis of 4515 reflections with Fo > 4σ(Fo) and 195 refined parameters. Alstonite is formed by the alternation, along c, of Ba-dominant and Ca-dominant layers, separated by CO3 groups parallel to {0001}. The main take-home message is to show that not all structure determinations of minerals/compounds can be solved routinely. Some crystals, even large ones displaying excellent diffraction quality, can be twinned in complex ways, thus making their study a crystallographic challenge.


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