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Charge-density studies of energetic materials: CL-20 and FOX-7
|Acta Crystallographica. Section B, Structural science Structural crystallography and crystal chemistry 64 (2008), No.1, pp.42-49|
| Journal Article|
|Fraunhofer ICT ()|
Experimental electron densities and derived properties have been determined for the two energetic materials CL-20 (3,5,9,11-tetraacetyl-14-oxo-1,3,5,7,9,11-hexaazapentacyclo-[5.5.3.02,6. 04,10.08,12]pentadecane), and FOX-7 (1,1-diamino- 2,2-dinitroethylene) from single-crystal diffraction. Synchrotron data extending to high scattering angles were measured at low temperature. Low figures-of-merit and excellent residuals were obtained. The Hansen & Coppens multipole-model electron density was compared with results from theoretical calculations via structure factors simulating an experiment. Chemical bonding in the molecules is discussed and a topological analysis gives insight especially into the character of those bonds that are thought to play a key role in the decomposition of the molecules. A comparison of theoretical and experimental electrostatic potentials shows no obvious evidence supporting earlier findings on other nitroheterocyclic molecules that electron-density maximanear the C-NO2 bonds mapped on the electron-density isosurface can be correlated with impact sensitivities. For FOX-7 periodic Hartree-Fock calculations were performed to investigate the influence of the crystal field on the electron density distribution.