The structure possesses square channels with a width of ca. 5.2 Е, which accounts for 14 % of the volume, and contains one methanol molecule per ion pair. <...> The cation interacts with three bromide ions through an anion—interaction and two C—H Br– interactions. <...> These interactions are investigated by DFT calculations. <...> Weak non-covalent interactions, such as —stacking [ 1 ] and n interactions [ 2, 3 ], are becoming increasingly recognised as important in crystal engineering. <...> These interactions in imidazolium salts, in combination with charge-assisted hydrogen bonding [ 4, 5 ], have proved to be useful in engineering polar crystal structures, for example those of 1-(2,3,4,5,6-pentafluorobenzyl)-3benzylimidazolium bromide (P1) [ 6 ] and 1-(2,3,5,6-tetrafluoropyridyl)-3-benzylimidazolium bromide 1 (Pna21) [ 7 ]. <...> The former possesses columns of —stacked pentafluorophenyl and phenyl rings and hydrogen bonding interactions orthogonal to them. <...> The latter possesses an interaction in which the tetrafluoropyridyl ring is sandwiched between a parallel phenyl ring (—stacking) and a bromide anion (anion— interaction) in addition to two charge-assisted hydrogen bonding C—H interactions involving the imidazolium ring. <...> The structure of the similar salt 1-(4-bromo-2,3,5,6tetrafluorophenyl)-3-benzylimidazolium bromide 2 possesses anion— interactions in columns of alternating bromofluorophenyl rings and bromide anions with Br Br– halogen bonding and C—H Br– interactions [ 8 ]. <...> In order to further investigate the interplay between interactions in polyfluoroarylimidazolium bromide salts a study of the structure of 1-(trifluoromethyl-2,3,5,6-tetrafluorophenyl)-3benzylimidazolium bromide 3 augmented by DFT calculations was undertaken. <...> Crystals of salt 3 were grown from methanol. <...> In addition to eight ion pairs of 3, the unit cell contained 147 electrons in a void of 528 Е3, which is consistent with ca. 8 molecules of methanol. <...> Consequently, this electron density was removed from the diffraction data. <...> CCDC 1413722 contains the supplementary crystallographic data for this paper. <...> These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033. <...> Energy and optimization calculations were performed using Gaussian09 [ 12 ] with the wB97XD [ 13 ] functional, which includes empirical dispersion, and the 6-311G++(2d,2p) basis set. <...> The optimized <...>