Structure of cis and trans-4-Bromophenylstyrylsulfones

Natural and synthetic zeolites form a variety of beautiful framework structures. These structures contain cages or cavities as well as channels. Access to these channels, cages or cavities is through a pore or window, which can be of the same size or smaller than their sizes. In cation-exchanged faujasite zeolites, the cage sizes always depend on the cation size. The geometrical isomerization of 4-bromophenyl styryl sulfone has been studied in solution media as well as in the presence of various cation-exchanged Y-type faujasite zeolites.1 In these zeolites, the cage free volume decreases as the cation size increases, resulting in an increase in the proportion of the cisisomer. Moreover, it is observed that while stirring as a hexane slurry, the cis-isomer 1 readily goes into the zeolite cage while the trans-isomer 2 remains in the hexane. This suggests that the molecular dimension of the trans-isomer is incompatible for its facile entry through the cage window. This interesting observation prompted us to grow single crystals of compounds 1 and 2 to gain more insight into their molecular structures, geometrical conformations and intermolecular interactions. The cis and trans forms of 4-bromophenyl styryl sulfone compounds were synthesized as per reported methods.2,3 The final products of 1 and 2 were crystallized by a slow-evaporation method using the solvent isooctane. Initially, both structures were confirmed by the H-NMR and C-NMR spectra. The selected geometrical parameters of both molecules [1 & 2] are given in Table 2. The hydrogen bonding interactions of 1 and 2 are presented in Table 3. Figures 2(a) and 2(b) show the molecular structures of 1 & 2 with thermal ellipsoid atoms. In 1 & 2, the S–C(9) bond lengths are 1.762(8) and 1.758(4)Å, respectively; an average, this dimension is slightly longer compared with S–C(8) [1.372(9) X-ray Structure Analysis Online