Structure of the Crystalline Compound Benzene-Bromine (1:1).

A Preliminary Study of Host-Guest Interactions in Polymeric Clathrates – An Ab Initio Study of the Model Complexes Benzene/X2 (X = F, Cl, Br, I)

“…Clearly, the T-shaped geometry is preferred for each of the halogens. This result is in suitable basis sets requires that one-electron properties, in Cl 2 [12] and benzene/Br 2 [13] complexes, which have shown centres of mass of the two molecules, which was varied during the that the T-shaped geometry is the most probable. The mini-potential energy surface scan, is indicated; the electrostatic fields generated by the two molecules are also indicated; starting from mum energy distances R, between the centres of mass of the 0.0 contours (dotted lines), positive and negative contours of the benzene and halogen molecules for the T-shaped struc-the electrostatic field (continuous and dashed lines, respectively) are tures are 3.9, 4.6, 4.7, and 4.9 Å for F 2 , Cl 2 , Br 2 , and I 2 , shown; the isopotential curves are spaced by 1 kcal/mol respectively.…”

“…Cl 2 [12] and benzene/Br 2 [13] systems have shown that a Tshaped geometry (see Figure 1), with the halogen molecule Recently, semicrystalline polymeric materials based on syndiotactic polystyrene that are able to absorb small mol-almost aligned along the C 6v symmetry axis of the benzene, is preferred. Furthermore, IR-spectroscopic studies indicate ecules, not only in the amorphous phase but also in the cavities of suitable crystalline phases, have been de-that an axial or slightly bent structure is also adopted in nitrogen matrices.…”

Changes in space and Laue groups of some published crystal structures

“…Br 2 Benzene.C12 (m. p. 233 K) and benzene.Br 2 (m. p. 259 K) were reported to be isomorphous (monoclinic, space group C2/m). The structure of the C12 compound was described in detail by Hassel & Stromme (1959;HS) and that of the Br 2 compound more briefly (Hassel & Stromme, 1958). These compounds have also been investigated by IR and Raman spectroscopy, with results that do not agree with the symmetry deduced by HS.…”

“…The quantity minimized was The C2/m cell dimensions reported for benzene. Br2 (a = 7.75, b = 8.83, c = 5.95 ./k, fl = 99.3 o;Hassel & Stromme, 1958) The initial IR study of these systems was by Person, Cook & Friedrich (1967), who studied benzene.Br 2 at 77 K. Their results were inconsistent with the site symmetry C2h required by the C2/m model of HS, and they concluded that the more likely site symmetry was C3v: they also noted that the crystal structure 'is very close to one with a rhombohedral unit cell ... with benzene and bromine molecules both located on sites of C3, symmetry'. Subsequently, Brown & Person (1977) re-examined the assignment of IR bands and concluded that, while C2n site symmetry could still be ruled out, 'positive identification of the site symmetry of the benzene as C3, is weakened considerably'.…”

Interaction of allylic carbocations with benzene: a theoretical model of carbocationic intermediates in terpene biosynthesis

“…It is known that coordinatively saturated cations interact with aromatic rings in a different manner than non-coordinatively saturated carbocations. 26 Until presently, studies of the interaction of an aromatic ring with protons and carbocations have focused on the Friedel-Crafts alkylation mechanism, 42,43,[45][46][47][48][49][50][51][52] and the formation or characterization of π- [53][54][55][56] and σ-complexes (Scheme 1- (4)). 57, 58 The formation of both complexes is dependent on the nature of the electrophile and on the aromatic ring.…”