Structural study of mefloquinium salts with three isomeric n-nitrobenzoates (n = 2, 3, and 4)

The crystal and molecular structures of three racemic erythro-(R*, S*)-(±)-α-2-piperidinyl-2,8-bis(trifluoromethyl)-4-quinolinemethanol n-nitrobenzoates, n = 2, 3, and 4, are described. The cations uniformly adopt an L-shaped geometry with protonation leading to a piperidin-1-ium ring in each case. A non-planar arrangement is found for the anion in (1; n = 2), owing to steric congestion, but almost planar arrangements are found in each of the anions in (2; n = 3) and (3; n = 4). Supramolecular chains are found in each of the crystal structures but these are sustained by different hydrogen bonding synthons. More efficient crystal packing in (3; n = 4) is correlated with a single synthon as opposed to two distinct synthons in each of (1; n = 2) and (2; n = 3). Crystal data for (1; n = 2): monoclinic, P21/n, a = 13.2144(6), b = 8.1028(2), c = 22.9724(9) Å, β = 105.919(1)°, V = 2365.41(15) Å3, Z = 4, R = 0.053. Crystal data for (2; n = 3): monoclinic, P21/n, a = 6.8389(2), b = 12.8432(4), c = 26.7910(9) Å, β = 90.868(2)°, V = 2352.87(13) Å3, Z = 4, R = 0.044. Crystal data for (3; n = 4): monoclinic, P21/n, a = 16.9854(8), b = 6.5069(2), c = 20.2083(9) Å, β = 92.116(2)°, V = 2231.94(16) Å3, Z = 4, R = 0.065.