Structure of 1,3,5-trichloro-2,4,6-trifluorobenzene

Abstract

The crystal structure of the symmetric 1,3,5-trichloro-2,4,6-trifluorobenzene, C6CIaF a, was determined at room temperature by single-crystal X-ray diffraction and at 4.2 K by neutron powder diffraction. The space group is P63/m with a hexagonal primitive cell of dimensions a = b = 8.541 (3) and c = 6.282 (2)/k [which become a = b = 8.441 (2) and c = 6.052 (2)/k at 4.2 K], V = 397/k 3 and Z = 2. The cell contains two planar molecules at 6 (2d) sites. The single-crystal R factor of 3.9% was reached with unconstrained refinement on 401 symmetry-independent Bragg intensities. The structure was solved using constrained refinement on the molecular orientation. Constrained refinement on the thermal parameters has indicated significant internal vibrations in the molecule. The low-temperature study showed there to be no phase transition when the powder is cooled.

Nature of halogen‐centered intermolecular interactions in crystal growth and design: Fluorine‐centered interactions in dimers in crystalline hexafluoropropylene as a prototype

“…In doing so, the importance of all other energy terms went unnoticed or was neglected. One cannot neglect the importance of the repulsive effects arising from Pauli exchange; this, together with the Coulomb type repulsion between the interacting fluorine atoms in this system, is expected, in part, to be responsible for the directionality of the F···F bonding interactions, as found in other systems . Also, the presence of the type‐II topology does not signify halogen bonding as shown in the study, since the interacting F atoms in the monomer were entirely negative.…”

“…Depending on the nature of the system, the energy of one of these interactions might be dominant, and does not permit the general conclusion to be reached that only electrostatics can explain the equilibrium geometry of a compound. Exchange and repulsion always compete with the attractive component to determine the directionality of halogen bonds, and hence the stability of the overall system …”

Introduction to the theory of lattice dynamics

“…Figure 15. Crystal structure [16] (left) and phonon dispersion curves (right) for the molecular crystal C 6 F 3 Cl 3 . This plot shows the low-frequency spectrum in which the molecules move as rigid objects [17].…”

“…In the reciprocal space of the face-centred cubic lattice, the k = (1, 0, 0) Brillouin zone boundary point is simply a lattice translation away from k = (1, 1, 0), and thus they are equivalent points. 16 The graph is drawn in a way that highlights this point, connecting the paths from k = (0, 0, 0) to the zone boundary via two directions. Next we consider the number of branches in the subgraphs.…”

Structural studies of the phase transition in N-isopropylcarbazole

“…A crystal of the high-temperature phase suitable for X-ray measurements was grown inside a Lindemann-glass capillary according to the procedure described elsewhere (Chaplot, Mclntyre, * A paper describing the structure of the high-temperature phase of NIPC appeared (Saravari, Kitamura, T.azuke, Takenaka & Sasada, 1984) while the present manuscript was in preparation. Mierzejewski & Pawley, 1981). Approximate dimensions of the sample were 0.3 x 0.5 x 0.4 mm.…”