Metal-free enantiomorphic perovskite [dabcoH(2)](2+)[H(3)O](+)Br(−) (3) and its one-dimensional polar polymorph

The structure and stoichiometry of a new metal-free and ammonium-free compound [dabcoH(2)](2+)H(3)O(+)Br(−) (3) (where [dabcoH(2)](2+) = 1,4-di­aza­bicyclo­[2.2.2]octane dication) correspond to the general formula ABX (3) characteristic of perovskites. In enantiomorphic trigonal polymorph α of [dabcoH(2)](2+)H(3)O(+)Br(−) (3), the corner-sharing [H(3)O]Br(6) octahedra combine into a 3D framework embedding [dabcoH(2)](2+) dications in pseudo-cubic cages. In the more dense polymorph β, the face-sharing [H(3)O]Br(6) octahedra form 1D polyanionic columns separated by [dabcoH(2)](2+) dications. These different topologies correlate with different crystal fields around the cations and their different disorder types: orientational disorders of [dabcoH(2)](2+) dications and H(3)O(+) cations in polymorph α and positional disorder of [H(3)O](+) cations in polymorph β. The orientational disorder increases the lengths of OH⋯Br hydrogen bonds in polymorph α, but NH⋯Br distances of ordered dabcoH(2) dications are longer in polymorph β. The presence of polar [H(3)O](+) cations in [dabcoH(2)](2+)H(3)O(+)Br(−) (3) polymorphs offers additional polarizability of the centres compared with analogous metal-free [dabcoH(2)](2+)[NH(4)](+)Br(−) (3) perovskite.