A method for the prediction of the crystal structure of ionic organic compounds—the crystal structures of o-toluidinium chloride and bromide and polymorphism of bicifadine hydrochloride

CrystEngComm ◽  
2004 ◽  
Vol 6 (53) ◽  
pp. 303-309 ◽  
Author(s):  
Patrick McArdle ◽  
Karen Gilligan ◽  
Desmond Cunningham ◽  
Rex Dark ◽  
Mary Mahon
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Organic Compounds

scholarly journals Syntheses, spectroscopy, and crystal structures of 3-(4-bromophenyl)-1,5-diphenylformazan and the 3-(4-bromophenyl)-1,5-diphenylverdazyl radical and the crystal structure of the by-product 5-anilino-3-(4-bromophenyl)-1-phenyl-1H-1,2,4-triazole

2018 ◽  
Vol 74 (3) ◽  
pp. 292-297 ◽  
Author(s):  
Gregor Schnakenburg ◽  
Andreas Meyer
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Organic Compounds ◽  
Spectroscopic Data ◽  
Structural Data ◽  
The Other ◽  
Side Product ◽  
Axis Direction ◽  
Verdazyl Radical ◽  
First Time

The title compounds, C19H15BrN4, C20H16BrN4and C20H15BrN4, are nitrogen-rich organic compounds that are related by their synthesis. The verdazyl radical, in which stacking leads to antiferromagnetic interactions, was reported previously [Iwaseet al.(2013).Phys. Rev. B,88, 184431]. For this compound, improved structural data and spectroscopic data are presented. The other two compounds have been crystallized for the first time and form stacks of dimers, roughly along thea-axis direction of the crystal. The formazan molecule shows signs of rapid intramolecular H-atom exchange typical for this class of compounds and spectroscopic data are provided in addition to the crystal structure. The triazole compound appears to be a side-product of the verdazyl synthesis.

scholarly journals Predicting crystal structures of organic compounds

2014 ◽  
Vol 43 (7) ◽  
pp. 2098-2111 ◽  
Author(s):  
Sarah L. Price
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Organic Compounds ◽  
Structure Prediction ◽  
Organic Crystal ◽  
Prediction Methods ◽  
Crystal Structure Prediction

Organic Crystal Structure Prediction methods generate the thermodynamically plausible crystal structures of a molecule. There are often many more such structures than experimentally observed polymorphs.

Topology of molecular packings in organic crystals

2000 ◽  
Vol 56 (6) ◽  
pp. 1035-1045 ◽  
Author(s):  
E. V. Peresypkina ◽  
V. A. Blatov
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Organic Compounds ◽  
Coordination Sphere ◽  
Molecular Packing ◽  
Organic Crystals ◽  
Topological Properties ◽  
Coordination Numbers ◽  
Intermolecular Contacts ◽  
Coordination Spheres

Using the methods of coordination sequences and of molecular Voronoi–Dirichlet polyhedra, the topological properties of molecular packings and molecular coordination numbers (MCNs) were determined in the crystal structures of 33 575 monosystem organic compounds within the first three coordination spheres. Numerous examples of disagreement between the topology of molecular packing and the system of intermolecular contacts in a crystal structure were found. It is concluded that within the first coordination sphere most of the molecules tend to arrange with MCN = 14, obeying the model of the thinnest covering of space, but molecular packings as a whole tend to be constructed according to one of the close packings.

On the inclusion of solvent molecules in the crystal structures of organic compounds

2000 ◽  
Vol 56 (3) ◽  
pp. 526-534 ◽  
Author(s):  
Carl Henrik Görbitz ◽  
Hans-Petter Hersleth
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Organic Compounds ◽  
Solvent Molecule ◽  
Water Molecules ◽  
Solvent Mixtures ◽  
Solvent Water ◽  
Different Types ◽  
Structural Database ◽  
Solvent Molecules

The Cambridge Structural Database has been searched for all crystal structures including organic solvent molecules (solvates) and solvent water molecules (hydrates). Well above 300 different solvent molecules were identified and the frequencies with which they occur in crystal structures, as a function of the year of publication, were established. The crystal structures are classified as `organic' and `metalloorganic'; it is shown that the relative prevalences of various cocrystallized solvents are different in the two groups. Several frequently used organic solvents are also common ligands for metal ions. Special interest has been focused on the existence of heterosolvates, i.e. crystal structures which include more than one type of solvent molecule. Up to five different types of solvent molecules were found in a single crystal structure. It is suggested that the use of solvent mixtures during crystallizations may prove to be a more useful and versatile approach for obtaining crystals of high-molecular-weight organic compounds than has hitherto been recognized.

PowderSolve– a complete package for crystal structure solution from powder diffraction patterns

1999 ◽  
Vol 32 (6) ◽  
pp. 1169-1179 ◽  
Author(s):  
G. E. Engel ◽  
S. Wilke ◽  
O. König ◽  
K. D. M. Harris ◽  
F. J. J. Leusen
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Organic Compounds ◽  
Powder Diffraction ◽  
Degrees Of Freedom ◽  
Solution Process ◽  
Structure Solution ◽  
Full Profile ◽  
Diffraction Patterns ◽  
And Performance

Powder diffraction techniques are becoming increasingly popular as tools for the determination of crystal structures. The authors of this paper have developed a software package, namedPowderSolve, to solve crystal structures from experimental powder diffraction patterns and have applied this package to solve the crystal structures of organic compounds with up to 18 variable degrees of freedom (defined in terms of the positions, orientations, and internal torsions of the molecular fragments in the asymmetric unit). The package employs a combination of simulated annealing and rigid-body Rietveld refinement techniques to maximize the agreement between calculated and experimental powder diffraction patterns. The agreement is measured by a full-profile comparison (using theRfactorRwp). As an additional check at the end of the structure solution process, accurate force-field energies may be used to confirm the stability of the proposed structure solutions. To generate the calculated powder diffraction pattern, lattice parameters, peak shape parameters and background parameters must be determined accurately before proceeding with the structure solution calculations. For this purpose, a novel variant of the Pawley algorithm is proposed, which avoids the instabilities of the original Pawley method. The successful application and performance ofPowderSolvefor crystal structure solution of 14 organic compounds of differing complexity are discussed.

Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems: synthesis and crystal structures of Rb2[(UO2)(Cr2O7)(NO3)2] and two new polymorphs of Rb2Cr3O10

2021 ◽  
Vol 236 (1-2) ◽  
pp. 11-21
Author(s):  
Evgeny V. Nazarchuk ◽  
Oleg I. Siidra ◽  
Dmitry O. Charkin ◽  
Stepan N. Kalmykov ◽  
Elena L. Kotova
Keyword(s):  
Crystal Structure ◽  
Aqueous Solutions ◽  
Crystal Structures ◽  
Hydrothermal Treatment ◽  
Ambient Conditions ◽  
Screw Axis ◽  
3D Framework ◽  
Solution Acidity

Abstract Three new rubidium polychromates, Rb2[(UO2)(Cr2O7)(NO3)2] (1), γ-Rb2Cr3O10 (2) and δ-Rb2Cr3O10 (3) were prepared by combination of hydrothermal treatment at 220 °C and evaporation of aqueous solutions under ambient conditions. Compound 1 is monoclinic, P 2 1 / c $P{2}_{1}/c$ , a = 13.6542(19), b = 19.698(3), c = 11.6984(17) Å, β = 114.326(2)°, V = 2867.0(7) Å3, R 1 = 0.040; 2 is hexagonal, P 6 3 / m $P{6}_{3}/m$ , a = 11.991(2), c = 12.828(3) Å, γ = 120°, V = 1597.3(5) Å3, R 1 = 0.031; 3 is monoclinic, P 2 1 / n $P{2}_{1}/n$ , a = 7.446(3), b = 18.194(6), c = 7.848(3) Å, β = 99.953(9)°, V = 1047.3(7) Å3, R 1 = 0.037. In the crystal structure of 1, UO8 bipyramids and NO3 groups share edges to form [(UO2)(NO3)2] species which share common corners with dichromate Cr2O7 groups producing novel type of uranyl dichromate chains [(UO2)(Cr2O7)(NO3)2]2−. In the structures of new Rb2Cr3O10 polymorphs, CrO4 tetrahedra share vertices to form Cr3O10 2− species. The trichromate groups are aligned along the 63 screw axis forming channels running in the ab plane in the structure of 2. The Rb cations reside between the channels and in their centers completing the structure. The trichromate anions are linked by the Rb+ cations into a 3D framework in the structure of 3. Effect of solution acidity on the crystallization of polychromates in uranyl-bearing systems is discussed.

scholarly journals Crystal Chemical Relations in the Shchurovskyite Family: Synthesis and Crystal Structures of K2Cu[Cu3O]2(PO4)4 and K2.35Cu0.825[Cu3O]2(PO4)4

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 807
Author(s):  
Ilya V. Kornyakov ◽  
Sergey V. Krivovichev
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structural Complexity ◽  
Crystal Chemical ◽  
X Ray Diffraction ◽  
Complexity Measures ◽  
X Ray ◽  
The Family ◽  
Similarities And Differences ◽  
Related Compounds

Single crystals of two novel shchurovskyite-related compounds, K2Cu[Cu3O]2(PO4)4 (1) and K2.35Cu0.825[Cu3O]2(PO4)4 (2), were synthesized by crystallization from gaseous phase and structurally characterized using single-crystal X-ray diffraction analysis. The crystal structures of both compounds are based upon similar Cu-based layers, formed by rods of the [O2Cu6] dimers of oxocentered (OCu4) tetrahedra. The topologies of the layers show both similarities and differences from the shchurovskyite-type layers. The layers are connected in different fashions via additional Cu atoms located in the interlayer, in contrast to shchurovskyite, where the layers are linked by Ca2+ cations. The structures of the shchurovskyite family are characterized using information-based structural complexity measures, which demonstrate that the crystal structure of 1 is the simplest one, whereas that of 2 is the most complex in the family.

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