Crystal Structure of the Trigonal Form of the 1:1 Complex Between Hexamethylbenzene and Hexafluorobenzene.

A Neutron and X‐Ray Diffraction Study of the Binary Liquid Aromatic System Benzene‐Hexafluorobenzene I. The Pure Components

“…So thermodynamical excess quantities [ 161 as well as anisotropic Rayleigh light scattering [ 171 and the Cotton-Mouton effect [I81 give probably good experimental evidence that a planar orientation occurs in the 1:l mixture. These findings are in agreement with quantum mechanical calculations [I91 and with the crystal structure of the 1 : 1 complex between hexamethylbenzene and hexafluorobenzene where partner molecules have been found to be orientated parallel [20].…”

An X-ray single-crystal study of the molecular system C6F6.C6D6

“…The best estimate leads to a molecular pairing with a separation of 3.52 A, with dimers separated by 3.71 A. Such a pairing is more likely to be stable in the lower phases, and would be consistent with the work of Dahl (1971Dahl ( , 1972Dahl ( , 1973 where forces stronger than van der Waals have been shown to exist in some HFB complexes.…”

“…Spectroscopic measurements by Beaumont & David (1967) and dipole measurements by Bauer, Knobler, Horsma & Perez (1970) of complexes containing HFB do not show any evidence of charge transfer between the different species of molecules as was first assumed by Patrick & Prosser (1960). This led to the X-ray diffraction studies of Dahl (1971Dahl ( , 1972Dahl ( , 1973, performed to gain information concerning the intermolecular forces present in the two complexes HFB-mesitylene and HFB-fiexamethylbenzene. Dahl concludes that the possibility of forces stronger than the van der Waals type should not be ignored in these systems.…”

Trichlorotricyanobenzene–hexamethylbenzene (1/1)

“…No structures of other complexes of trichlorotricyanobenzene have been reported. Structures have been reported for complexes of hexamethylbenzene with chloranil (Harding & WaUwork, 1955;Jones & Marsh, 1962), tetracyanobenzene (Niimura, Ohashi & Saito, 1968), hexafluorobenzene (Dahl, 1972(Dahl, , 1973, tetracyanoquinodimethane (Colton & Henn, 1970;Johnson, Reed, Hall & Raaen, 1974), tetracyanoethylene * Lists of anisotropic thermal parameters, H-atom parameters, deviations from planarity, distances between the two molecules, and observed and calculated structure factors have been deposited with the British Library Document Supply Centre as Supplementary Publication No. SUP 51231 (14 pp.).…”