Decafluorocyclohex-1-ene at 4.2 K – crystal structure and theoretical analysis of weak interactions

Abstract

The crystal structure of 1,2,3,3,4,4,5,5,6,6-decafluorocyclohex-1-ene (decafluorocyclohex-1-ene, C6F10) was solved in direct space from neutron powder diffraction data previously collected at 4.2 K [Pawley, G. S. (1981). J. Appl. Cryst. 14, 357-361] and refined by energy minimization in the solid state. To optimize the positions of the 64 atoms in the monoclinic computational cell the PBESOL and hybrid PBE0 functionals were used. The crystal structure of the title compound, which is liquid at room temperature, is built of antiparallel pairs of molecules assembled into molecular columns stacked along the a axis. Dominating the crystal-building forces are weak intermolecular dispersion interactions. Bonding conditions in the structure were analysed by theoretical molecular calculations of representative next-neighbor molecular dimers carried out using dispersion-corrected density functional theory (DFT) functionals and the SCS-MP2 wavefunction method. The largest interaction energy is of the order of ∼ 21 kJ mol(-1), above the interaction energy of a benzene dimer (11.3 kJ mol(-1)) and close to that of a water dimer (20.9 kJ mol(-1)). The interaction energy for the second most stable dimer can be compared with either that of a benzene dimer or of a C-H...π hydrogen bond. The remaining five weakly interacting dimers (∼ 4.2-8.4 kJ mol(-1)) can be characterized as having stronger interactions than those of methane dimers (-2.2 kJ mol(-1)), but weaker than those of benzene molecule pairs or weak C-H...C interactions for instance.

Intermolecular interactions and chiral crystallization effects in (1,5,3-dithiazepan-3-yl)-alkanoic acids

“…The chiral derivatives 5-8 were shown to form R 1 2 (6), R 2 2 (7), and R 2 2 (8) dimeric associates between the dithiazepane cycle (7), and 3-(1,5,3-dithiazepan-3-yl)-2-phenylpropanoic acid (8) has been performed according to the methods described earlier. The dithiazepane cycle in 1,5,3-dithiazepan-3-ol 1, in 2a and in those with chiral fragments 5-8 was shown to adopt a pseudo-chair conformation, whereas in compounds 2b, 3, and 4 with achiral moieties, it possesses a pseudo-boat conformation.…”

“…[1][2][3][4][5][6][7][8] This is also true for amino acids and their various derivatives. [1][2][3][4][5][6][7][8] This is also true for amino acids and their various derivatives.…”

Combined powder X-ray diffraction data and quantum-chemical calculations in EXPO2014

“…(4) Selecting the correct structure from a set of potential structures that differ in the torsion angle rotation of functional group (Naelapää et al , 2012) or in the space group, and could not be distinguished on the basis of the PXRD data alone. (5) Geometry optimization with dispersion-corrected DFT (DFT-D) approach in the solid state for refining crystal structure and providing results whose accuracy is comparable with that of single crystal, especially when, the Rietveld refinement yields inaccurate molecular geometry (Smrcok et al , 2013). (7) Assessment of the correctness of experimental crystal structures (van de Streek and Neumann, 2010).…”

Face-sharing octahedra in Cs3Al2F9 and Cs2AlF5

“…This study provides a resolution of aluminium coordination ambiguity in the structures of Cs 3 Al 2 F 9 and Cs 2 AlF 5 . As these compounds do not form single crystal of reasonable size for X-ray diffraction, their structures were solved from laboratory powder diffraction data, refined by Rietveld (1969) method and finished by energy minimization in the solid state (see, e.g., Le Bail and Smrčok, 2011; Oszajca et al , 2013; Smrčok et al , 2013).…”