Crystal and molecular structures of 2-[1-(2-aminoethyl)-2-imidazolidinylidene]-2-nitro-acetonitrile (C7H11N5O2) and 2,6-dianlino-5-hydroxy-3-nitro-4H-pyrazolo[1,5-a]-pyrimidin-7-one monohydrate (C6H6N6O4•H2O) from X-ray, synchrotron and neutron powder diffraction data

被引:26
作者
Chernyshev, VV [1 ]
Fitch, AN
Sonneveld, EJ
Kurbakov, AI
Makarov, VA
Tafeenko, VA
机构
[1] Moscow MV Lomonosov State Univ, Dept Chem, Moscow 119899, Russia
[2] European Synchrotron Radiat Facil, F-38043 Grenoble, France
[3] Univ Amsterdam, Crystallog Lab, NL-1018 WV Amsterdam, Netherlands
[4] Russian Acad Sci, Inst Nucl Phys, Gatchina 188350, Russia
[5] State Sci Ctr NIOPIK, Dept Med Chem, Moscow 103787, Russia
来源
ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL SCIENCE CRYSTAL ENGINEERING AND MATERIALS | 1999年 / 55卷
关键词
D O I
10.1107/S010876819900213X
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The crystal and molecular structures of 2-[1-(2-aminoethyl) -2-imidazolidinylidene]-2-nitroacetonitrile [C7H11N5O2; space group P2(1)/n; Z = 4; a = 7.4889 (8), b = 17.273 (2), c = 7.4073 (8) Angstrom, beta = 111.937 (6)degrees], (I), and 2,6-diamino-5-hydroxy-3-nitro-4H-pyrazolo [1,5-a]-pyrimidin-7-one monohydrate [C6H6N6O4. H2O; space group P2(1)/n; Z = 4; a 17.576(3), b = 10.900(2), 4.6738 (6) Angstrom, beta = 9..867(8)degrees], (II), have been determined from X-ray, synchrotron and neutron powder diffraction data using various methods. The structures were originally solved from Guinier photographs with a grid search procedure and the program MRIA using a priori information from NMR and mass spectra on the possible geometry of the molecules. Because the conformation of molecule (I) changed during the bond-restrained Rietveld refinement, solvent water was found in (II) and, moreover, as both Guinier patterns were corrupted by texture, high-resolution texture-free synchrotron data were collected at the BM16 beamline, ESRF to confirm the original results. Using the set of \F\(2) values derived from the synchrotron patterns after full-pattern decomposition procedures, the structures of (I) and (II) were solved by direct methods via SHELXS96, SIRPOW.92 and POWSIM without any preliminary models of the molecules, and by Patterson search methods via DIRDIF96 and PATSEE with the use of rigid fragments from each of the molecules. The neutron patterns allowed (I) and (II) to be solved using the grid search procedure and correct initial models of the molecules including H atoms. The results obtained from powder patterns measured on different devices demonstrate the high level of reproducibility and reliability of various powder software and equipment, with a certain preference for synchrotron facilities.
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页码:554 / 562
页数:9
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