Crystal structure of propio­nitrile (CH3CH2CN) determined using synchrotron powder X-ray diffraction

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International Union of Crystallography
The structure and thermal expansion of the astronomical molecule propio­nitrile have been determined from 100 to 150 K using synchrotron powder X-ray diffraction. This temperature range correlates with the conditions of Titan's lower stratosphere, and near surface, where propio­nitrile is thought to accumulate and condense into pure and mixed-nitrile phases. Propio­nitrile was determined to crystallize in space group, Pnma (No. 62), with unit cell a = 7.56183 (16) Å, b = 6.59134 (14) Å, c = 7.23629 (14), volume = 360.675 (13) Å3 at 100 K. The thermal expansion was found to be highly anisotropic with an eightfold increase in expansion between the c and b axes. These data will prove crucial in the computational modelling of propio­nitrile–ice systems in outer Solar System environments, allowing us to simulate and assign vibrational peaks in the infrared spectra for future use in planetary astronomy. © 2020 International Union of Crystallography
Crystal structure, Synchrotrons, X-ray diffraction, Thermal expansion, Ice, Planetary atmospheres, Satellites, Nitriles
Brand, H. E. A, Gu, Q., Kimpton, J. A., Auchettl, R.& Ennis, C.(2020). Crystal structure of propionitrile (CH3CH2CN) determined using synchrotron powder X-ray diffraction. Journal of Synchrotron Radiation, 27, 212-216. doi:10.1107/S1600577519015911