Syntheses and crystal structures of a new family of hybrid perovskites: C(5)H(14)N(2)·ABr(3)·0.5H(2)O (A = K, Rb, Cs)

The syntheses and crystal structures of three hybrid perovskites, viz. poly[1-methyl­piperizine-1,4-diium [tri-μ-bromido-potassium] hemihydrate], {(C(5)H(14)N(2))[KBr(3)]·0.5H(2)O}(n), (I), poly[1-methyl­piperizine-1,4-diium [tri-μ-bromido-rubidium] hemihydrate], {(C(5)H(14)N(2))[RbBr(3)]·0.5H(2)O}(n), (II), and poly[1-methyl­piperizine-1,4-diium [tri-μ-bromido-caesium] hemihydrate], {(C(5)H(14)N(2))[CsBr(3)]·0.5H(2)O}(n), (III), are described. These isostructural (space group Amm2) phases contain a three-dimensional, corner-sharing network of distorted ABr(6) octa­hedra (A = K, Rb, Cs) with the same topology as the classical perovskite structure. The doubly protonated C(5)H(14)N(2) (2+) cations occupy inter­stices bounded by eight octa­hedra and the water mol­ecules lie in square sites bounded by four octa­hedra. N—H⋯Br, N—H⋯(Br,Br), N—H⋯O and O—H⋯Br hydrogen bonds consolidate the structures.