The structure of cimetidine (C10H16N6S) solved from synchrotron-radiation X-ray powder diffraction data

Cernik, Robert J.; Cheetham, Anthony K.; Prout, C. K.; Watkin, David J.; Wilkinson, Angus P.; Willis, B. T. M.

doi:10.1107/s0021889890013486

Cited by 94 publications

(39 citation statements)

References 10 publications

(10 reference statements)

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“…The remaining three oxygen positions were located in the first difference Fourier map, and subsequent refinement revealed the location of the partially disordered 1-aminoadamantane. A much larger problem was the structure of the drug cimetidine, which contains 33 atoms in the asymmetric unit, and was again solved using synchrotron data (Cernik, Cheetham, Prout, Watkin, Wilkinson & Willis, 1991). The powder pattern and model fit to the determined structure are shown in Fig.…”

Section: Structure Determination From Powdersmentioning

confidence: 99%

The complementary use of X-ray and neutron diffraction in the study of crystals

Finney¹

1995

Acta Crystallogr Sect B

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Neutrons and X-rays interact differently with atoms in crystals. While X-rays primarily give information on electron distributions, neutrons report on nuclear positions, and, through the spin interaction, are sensitive to magnetic structure. These and other differences have been exploited tbr many years in, for example, X-N difference studies and in determining magnetic structure. The major differences in available X-ray and neutron incident-beam intensities have also influenced the ways in which the two probes are exploited; not only are neutron sources inherently weaker, but this disadvantage is heightened by the weaker neutron-nucleus interaction. Advances in sources of both types, coupled with developments in instrumentation, have enabled not only the relative strengths to be exploited more effectively, but also some of the respective weaknesses in both techniques to be at least partially overcome. After outlining the main relevant advantages of X-rays and neutrons, and specifically of pulsed spallation neutron sources, this paper will discuss some of the scientific areas in which these various advantages are being increasingly exploited with advanced sources and instrumentation. Although the examples focus in particular on studies of structure and disorder in powder samples, including work at high pressures, some attention is given to hydrogen location in, and diffuse scattering from, single crystals. Finally, a personal forward look towards possible future developments is offered.

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Section: Structure Determination From Powdersmentioning

confidence: 99%

The complementary use of X-ray and neutron diffraction in the study of crystals

Finney¹

1995

Acta Crystallogr Sect B

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“…The diffractometer is based on the design of Parrish & Hart (1985). The experimental setup was similar to that described by Cernik et al (1991). The data were collected using a rotating¯at-plate sample holder over the 2 range 5±80 in 0.01 steps at ambient conditions.…”

Section: Methodsmentioning

confidence: 99%

Ab initiostructure determination of sulfathiazole polymorph V from synchrotron X-ray powder diffraction data

et al. 1999

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The crystal structure of sulfathiazole [4-amino-N-(2,3-dihydro-2-thiazolylidene)benzenesulfonamide, C 9 H 9 -N 3 O 2 S] polymorphic form V has been determined from high-resolution synchrotron X-ray powder diffraction data. The structure is monoclinic, space group P2 1 /n, Z = 8, with two molecules in the asymmetric unit. The unit-cell dimensions are a = 14.3296 (3), b = 15.2733 (2), c = 10.4428 (2) A Ê and = 91.052 (1) with cell volume V = 2285.13 (8) A Ê 3 . The structure has been solved by direct methods without recourse to any computational modelling techniques for generating possible structures. The unre®ned structure obtained from direct methods gave an R wp value of 36.5%. Re®nement of atomic and displacement parameters yielded a ®nal R wp of 12.54% (R p = 9.37%). The conformations of the two molecules in the asymmetric unit are nearly identical and very similar to that found in other forms of sulfathiazole. The molecular packing is characterized by molecular sheets lying perpendicular to the a axis. Each sheet is two molecules thick, being integrated by hydrogen bonding. With 16 non-H atoms in the molecule and two molecules in the asymmetric unit, this structure represents a further advance in terms of the complexity of an organic structure solved from X-ray powder diffraction data.

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“…The study by Cernik et al (1991) on cimetidine (C 10 H 16 N 6 S) was a demonstration of the potential of the powder method for structure solution of organic compounds, as one was able by an iterative method to locate all the 17 non-hydrogen atoms in the molecule. These authors also compared their result with that of a single-crystal study; the average difference in bond lengths (calculated by us based on their published data) was 0.044 (33) A Ê .…”

Section: Resultsmentioning

confidence: 99%

“…In particular, the paper by Cernik et al (1991) stimulated investigation on organic compounds with the powder method. A list of the structures solved during recent years, among them several molecular organic compounds, can be found in the overview given by Le Bail (1999).…”

Section: Introductionmentioning

confidence: 99%

Accuracy of molecular structures determined from high-resolution powder diffraction. The example ofm-fluorobenzoic acid

Pattison

Knudsen²,

Fitch

2000

J Appl Cryst

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The accuracy with which it is possible to determine atomic coordinates of light atoms at arbitrary positions using X-ray powder data alone is demonstrated. For this purpose use is made of synchrotron powder diffraction data obtained for an organic molecule, m-¯uorobenzoic acid, consisting of ten non-hydrogen atoms (C 7 H 5 FO 2 ). The results are compared with those of a single-crystal study on the same compound, and in particular the differences in bond lengths and bond angles are studied. The structure solution produced by direct methods is compared with the ®nal result after the Rietveld re®nement. The effect of performing the data collection at room temperature and at 100 K is also investigated. The bond lengths extracted from the powder data were found to differ from the single-crystal values by an average of 0.025 A Ê when data collected at room temperature were employed, and by 0.021 A Ê when using 100 K data. For the bond angles the corresponding values were 3.5 and 1.5 , respectively. With the low-temperature data it was possible to re®ne all atoms, including the hydrogen atoms, without restraints, whereas for the data collected at room temperature, strong restraints had to be used for the hydrogen atoms.

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The structure of cimetidine (C₁₀H₁₆N₆S) solved from synchrotron-radiation X-ray powder diffraction data

Cited by 94 publications

References 10 publications

The complementary use of X-ray and neutron diffraction in the study of crystals

The complementary use of X-ray and neutron diffraction in the study of crystals

Ab initiostructure determination of sulfathiazole polymorph V from synchrotron X-ray powder diffraction data

Accuracy of molecular structures determined from high-resolution powder diffraction. The example ofm-fluorobenzoic acid

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