Arrangement of Rh3+ions infac-triamminetrichloridorhodium from powder data and infac-triamminetrinitratorhodium crystals twinned by merohedry

2013 ◽  
Vol 69 (12) ◽  
pp. 1462-1466 ◽  
Author(s):  
Alexander D. Vasiliev ◽  
Maxim S. Molokeev ◽  
Iraida A. Baidina ◽  
Anatoly V. Belyaev ◽  
Sofiya N. Vorob'eva

The rhodium complexes [RhCl3(NH3)3], (I), and [Rh(NO3)3(NH3)3], (II), are built from octahedral RhX3(NH3)3units; in (I) they are isolated units, while in (II) the units are stacked in columns with partially filled sites for the Rh atoms. The octahedra of monoclinic crystals of (I) are linked by N—H...Cl hydrogen bonds and the Rh3+ions are located on the mirror planes. In the trigonal crystals of (II), the discontinuous `columns' along the threefold axis are linked by N—H...O hydrogen bonds. The structure of (I) has been solved using laboratory powder diffraction data, the structure of (II) has been solved by single-crystal methods using data from a merohedrally twinned sample. Both compounds possess low solubility in water.

2019 ◽  
Vol 234 (4) ◽  
pp. 257-268 ◽  
Author(s):  
Carina Schlesinger ◽  
Michael Bolte ◽  
Martin U. Schmidt

Abstract Structure solution of molecular crystals from powder diffraction data by real-space methods becomes challenging when the total number of degrees of freedom (DoF) for molecular position, orientation and intramolecular torsions exceeds a value of 20. Here we describe the structure determination from powder diffraction data of three pharmaceutical salts or cocrystals, each with four molecules per asymmetric unit on general position: Lamivudine camphorsulfonate (1, P 21, Z=4, Z′=2; 31 DoF), Theophylline benzamide (2, P 41, Z=8, Z′=2; 23 DoF) and Aminoglutethimide camphorsulfonate hemihydrate [3, P 21, Z=4, Z′=2; 31 DoF (if the H2O molecule is ignored)]. In the salts 1 and 3 the cations and anions have two intramolecular DoF each. The molecules in the cocrystal 2 are rigid. The structures of 1 and 2 could be solved without major problems by DASH using simulated annealing. For compound 3, indexing, space group determination and Pawley fit proceeded without problems, but the structure could not be solved by the real-space method, despite extensive trials. By chance, a single crystal of 3 was obtained and the structure was determined by single-crystal X-ray diffraction. A post-analysis revealed that the failure of the real-space method could neither be explained by common sources of error such as incorrect indexing, wrong space group, phase impurities, preferred orientation, spottiness or wrong assumptions on the molecular geometry or other user errors, nor by the real-space method itself. Finally, is turned out that the structure solution failed because of problems in the extraction of the integrated reflection intensities in the Pawley fit. With suitable extracted reflection intensities the structure of 3 could be determined in a routine way.


Author(s):  
Robert A. Toro ◽  
Analio Dugarte-Dugarte ◽  
Jacco van de Streek ◽  
José Antonio Henao ◽  
José Miguel Delgado ◽  
...  

The structure of racemic (RS)-trichlormethiazide [systematic name: (RS)-6-chloro-3-(dichloromethyl)-1,1-dioxo-3,4-dihydro-2H-1λ6,2,4-benzothiadiazine-7-sulfonamide], C8H8Cl3N3O4S2 (RS-TCMZ), a diuretic drug used in the treatment of oedema and hypertension, was determined from laboratory X-ray powder diffraction data using DASH [David et al. (2006). J. Appl. Cryst. 39, 910–915.], refined by the Rietveld method with TOPAS-Academic [Coelho (2018). J. Appl. Cryst. 51, 210–218], and optimized using DFT-D calculations. The extended structure consists of head-to-tail dimers connected by π–π interactions which, in turn, are connected by C—Cl...π interactions. They form chains propagating along [101], further connected by N—H...O hydrogen bonds to produce layers parallel to the ac plane that stack along the b-axis direction, connected by additional N—H...O hydrogen bonds. The Hirshfeld surface analysis indicates a major contribution of H...O and H...Cl interactions (32.2 and 21.7%, respectively). Energy framework calculations confirm the major contribution of electrostatic interactions (E elec) to the total energy (E tot). A comparison with the structure of S-TCMZ is also presented.


1997 ◽  
Vol 53 (6) ◽  
pp. 861-869 ◽  
Author(s):  
C. D. Ling ◽  
J. G. Thompson ◽  
S. Schmid ◽  
D. J. Cookson ◽  
R. L. Withers

The structures of the layered intergrowth phases SbIIISb^{\rm V}_xAl-xTiO6 (x \simeq 0, A = Ta, Nb) have been refined by the Rietveld method, using X-ray diffraction data obtained using a synchrotron source. The starting models for these structures were derived from those of Sb^{\rm III}_3Sb^{\rm V}_xA 3−xTiO14 (x = 1.26, A = Ta and x = 0.89, A = Nb), previously solved by single-crystal X-ray diffraction. There were no significant differences between the derived models and the final structures, validating the approach used to obtain the models and confirming that the n = 1 and n = 3 members of the family, Sb^{\rm III}_nSb^{\rm V}_xA n−xTiO4n+2 are part of a structurally homologous series.


CrystEngComm ◽  
2020 ◽  
Vol 22 (21) ◽  
pp. 3692-3700
Author(s):  
G. A. Kostin ◽  
E. Yu. Filatov ◽  
D. P. Pischur ◽  
N. V. Kuratieva ◽  
S. V. Korenev

A reversible order–disorder phase transition in [Pd(NH3)4][RuNO(NO2)4OH] in the temperature range of 370–390 K was confirmed by DSC, single crystal and powder diffraction data.


2020 ◽  
Vol 35 (4) ◽  
pp. 282-285
Author(s):  
Zhicheng Zha ◽  
Ting Tang ◽  
Xiaoyan Bian ◽  
Qing Wang

X-ray powder diffraction data for estra-4,9-diene-3,17-dione, C18H22O2, are reported [a = 9.236(7) Å, b = 10.294(4) Å, c = 15.471(1) Å, unit cell volume V = 1471.11 Å3, Z = 4, and space group P212121]. All measured lines were indexed and are consistent with the P212121 space group. No detectable impurities were observed. The single-crystallographic data of the compound are also reported [a = 9.2392(7) Å, b = 10.2793(5) Å, c = 15.4822(7) Å, unit cell volume V = 1470.37(15) Å3, Z = 4, and space group P212121]. Both single-crystal and powder diffraction methods can get the similar structure data.


2013 ◽  
Vol 69 (12) ◽  
pp. 1549-1552 ◽  
Author(s):  
Vladimir V. Chernyshev ◽  
Sergey Y. Efimov ◽  
Ksenia A. Paseshnichenko ◽  
Andrey A. Shiryaev

The title salt, C8H12NO+·C7H10NO5−, crystallizes in two polymorphic modifications,viz.monoclinic (M) and orthorhombic (O). The crystal structures of both polymorphic modifications have been established from laboratory powder diffraction data. The crystal packing motifs in the two polymorphs are different, but the conformations of the anions are generally similar. InM, the anions are linked by pairs of hydrogen bonds of the N—H...O and O—H...O types into chains along theb-axis direction, and neighbouring molecules within the chain are related by the 21screw axis. The cations link these chainsviaO—H...O and N—H...O hydrogen bonds into layers parallel to (001). InO, the anions are linked by O—H...O hydrogen bonds into helices along [001], and neighbouring molecules within the helix are related by the 21screw axis. The neighbouring helical turns are linked by N—H...O hydrogen bonds. The cations link the helicesviaO—H...O and N—H...O hydrogen bonds, thus forming a three-dimensional network.


2013 ◽  
Vol 69 (2) ◽  
pp. i11-i12 ◽  
Author(s):  
Yongho Kee ◽  
Hoseop Yun

The structure of Li3V2(PO4)3has been reinvestigated from single-crystal X-ray data. Although the results of the previous studies (all based on powder diffraction data) are comparable with our redetermination, all atoms were refined with anisotropic displacement parameters in the current study, and the resulting bond lengths are more accurate than those determined from powder diffraction data. The title compound adopts the Li3Fe2(PO4)3structure type. The structure is composed of VO6octahedra and PO4tetrahedra by sharing O atoms to form the three-dimensional anionic framework∞3[V2(PO4)3]3−. The positions of the Li+ions in the empty channels can vary depending on the synthetic conditions. Bond-valence-sum calculations showed structures that are similar to the results of the present study seem to be more stable compared with others. The classical charge balance of the title compound can be represented as [Li+]3[V3+]2[P5+]3[O2−]12.


Author(s):  
Michel Fleck ◽  
Ekkehart Tillmanns ◽  
Ladislav Bohatý ◽  
Peter Held

AbstractThe crystal structures of eight different L-malates have been determined and refined from single-crystal X-ray diffraction data. The compounds are the monoclinic (space groupIn addition, for all the compounds, powder diffraction data were collected, analysed and submitted to the powder diffraction file (PDF).


2009 ◽  
Vol 42 (6) ◽  
pp. 1054-1061 ◽  
Author(s):  
A. D. Fortes ◽  
I. G. Wood ◽  
K. S. Knight

The crystal structure of perdeuterated methanol monoammoniate, CD3OD·ND3, has been solved from neutron powder diffraction data collected at 4.2 and 180 K. The crystal structure is orthorhombic, space groupPbca(Z= 8), with unit-cell dimensionsa= 11.02320 (7),b= 7.66074 (6),c= 7.59129 (6) Å,V= 641.053 (5) Å3[ρcalc= 1162.782 (9) kg m−3] at 4.2 K, anda= 11.21169 (5),b= 7.74663 (4),c= 7.68077 (5) Å,V= 667.097 (4) Å3[ρcalc= 1117.386 (7) kg m−3] at 180 K. The crystal structure was determined byab initiomethods from the powder data; atomic coordinates and anisotropic displacement parameters were subsequently refined by the Rietveld method toRp< 3% at both temperatures. The crystal comprises a sheet-like structure in thebccrystallographic plane, consisting of strongly hydrogen bonded elements; these sheets are stacked along theaaxis, and adjacent sheets are linked by what may be comparatively weak C—D...O hydrogen bonds. Within the strongly bonded sheet structure, ND3molecules are tetrahedrally coordinated by the hydroxy moieties of the methanol molecule, accepting one hydrogen bond (O—D...N) of length ∼1.75 Å, and donating three hydrogen bonds (N—D...O) of length 2.15–2.25 Å. Two of the methyl deuterons appear to participate in weak interlayer hydrogen bonds (C—D...O) of length 2.7–2.8 Å. The hydrogen bonds are ordered at both 4.2 and 180 K. The relative volume change on warming from 4.2 to 180 K, ΔV/V, is +4.06%, which is comparable to, but more nearly isotropic (as determined from the relative change in axial lengths,e.g.Δa/a) than, that observed in deuterated methanol monohydrate.


Sign in / Sign up

Export Citation Format

Share Document