Bromine molecule crystal structure

The crystal structure of 2-bromo-l,4-phenylenediyl bis(tran5-4-n-prop-ylcyclohexanoate) was determined by Hartung and Winter [114]. The molecules exhibit pseudo-centrosymmetry in consequence of a special kind of disorder within the crystal lattice. The peculiarity of the crystal structure is the disorder of the molecules with respect to the position of their bromine atoms which occupy the 2- or 5-position of the phenyl ring in a statistical manner. 

Antimony(III) halides are powerful halide acceptors and form complexes with, for example, monovalent halides to give a variety of interesting structures, e.g. (54)-(56). The tetramethyl-ammonium nonabromodiantimonate(III) dibromine is of interest since the crystal structure contains bromine molecules which bridge the [Sb2Br9]3 anions (56).158... 

The O—Br bonds of (35) (1.98 A) are also longer than the sum of the covalent radii of oxygen and bromine atoms (1.81 A). The crystal structure of (35) reveals some interaction between adjacent molecules (Figure 2). The distance between the bromine atom of one molecule and its nearest oxygen atom of a neighboring molecule is only 2.97 A, well within the sum of the van der Waals radii (3.35 A) of bromine and oxygen. This suggests a measure of Lewis acidity at the bromine of such species. 

The X-ray crystal structures of a number of compounds of general formula [PdBr2L3] have been determined, for example when L = 2-phenylisophosphinoline (2), the structures of both racemic and optically resolved forms were determined," and when L = (3), the structure of [PdBr2L3]-PhCl was obtained.26 The geometry of all these molecules is similar, being distorted tetragonal pyramidal with an apical bromine. 

It is a stable salt and can be sublimed at 200°C. The X-ray crystal structure of Br2+Sb3F16 329 shows a bromine-bromine bond distance of 2.13 A. The shorter bond distance of 329 compared to neutral bromine is in accord with increase in bond order resulting from the loss of an antibonding electron from the neutral molecule.800,801... 

The crystal structure of 2,4,5,6-tetrabromo-l,3-dimethylbenzene (46) (Strel tsova and Struchkov, 1961b) is disordered in such a way that it is not possible to distinguish between bromine atoms and methyl groups in the molecule. The exocyclic atoms are displaced (0-018 A) alternately above and below the aromatic plane. Here again the level of significance is such that it is impossible to say whether or not intramolecular overcrowding is the cause of these deviations. 

Crystal structures of some bromine-substituted compounds were selected from the CSD according to the criteria (b) to (e) used for the chlorinated compounds. The number of minimum bromine atoms per molecule [criterion (a)] was reduced to 3 for C(sp3)—Br bonds and to 2 for C(sp2)—Br bonds. With these restrictions 43 observations were listed for C(sp3)—Br bonds with a mean value of 195.6 pm and a large standard deviation of 6.5 pm. The individual values range from 179.4 pm to 224.8 pm. The extreme values are listed in Table 41. The mean distance of 47 C(sp2)—Br bonds is 189.0 pm with a standard deviation of 2.2 pm. The individual values vary from 185.1 to 195.9 pm. Some examples of these recent crystal studies are given in Tables 41 and 42. 

The bromination of poly-DCH is of interest because the degree of bromine uptake can be controlled, by choice of experimental conditions, between 3 and 8 Br atoms per polymer repeat unit and because a crystal-to-crystal transformation is observed. Scheme 1 summarizes the reactions of liquid bromine with poly-DCH. Interaction of poly-DCH crystals with dense vapors of bromine or cyanogen bromide for months did not lead to detectable weight gain. By contrast, DCH monomer (2a), which has a crystal structure similar to the polymer (6), readily reacts with bromine vapor to give an eunor-phous material which has gainbd ca 12 Br atoms per molecule. 

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