The Crystal Structures of Hexamethyleneiminium p-Chlorobenzoate and Dimorphs of Hexamethyleneiminium p-Bromobenzoate

The crystal structures of hexamethyleneiminium p-chlorobenzoate (1), and the monoclinic [2(m)] and orthorhombic [2(o)] forms of hexamethyleneiminium p-bromobenzoate have been determined from visually estimated Cu Kα data. The crystal data are: P21c, a=10.10(2), b=16.78(1), c=9.01(2) A, β=118.4(2)°, Z=4 for 1; C2/c, a=25.47(2), b=7.01(1), c=16.29(1) A, β=109.1(1)°, Z=8 for 2(m); and Pbca, a=11.55(1), b=27.40(1), c=8.57(1) A, Z=8 for 2(o). The structures of 1, 2(m), and 2(o) were refined to R values of 0.072, 0.100, and 0.083 for 1628, 1009, and 1013 non-zero reflections, respectively. In the crystals of 1, the type of hydrogen bond and the molecular arrangement in (010) plane are the same as those in piperazinediylium terephthalate. In 2(m), two pairs of the base and acid ions related by a twofold axis are linked together by N–H···O hydrogen bonds. The crystal structure of 2(o) is very similar to that of piperidinium and pyrrolidinium p-substituted benzoates in Pbca, but there is a difference in the combin...