Syntheses and crystal structures of a new family of hybrid perovskites: C5H14N2·ABr3·0.5H2O (A = K, Rb, Cs).

The syntheses and crystal structures of three hybrid perovskites, viz. poly[1-methyl-piperizine-1,4-diium [tri-μ-bromido-potassium] hemihydrate], {(C5H14N2)[KBr3]·0.5H2O} n , (I), poly[1-methyl-piperizine-1,4-diium [tri-μ-bromido-rubidium] hemihydrate], {(C5H14N2)[RbBr3]·0.5H2O} n , (II), and poly[1-methyl-piperizine-1,4-diium [tri-μ-bromido-caesium] hemihydrate], {(C5H14N2)[CsBr3]·0.5H2O} n , (III), are described. These isostructural (space group Amm2) phases contain a three-dimensional, corner-sharing network of distorted ABr6 octa-hedra (A = K, Rb, Cs) with the same topology as the classical perovskite structure. The doubly protonated C5H14N2 2+ cations occupy inter-stices bounded by eight octa-hedra and the water mol-ecules lie in square sites bounded by four octa-hedra. N-H⋯Br, N-H⋯(Br,Br), N-H⋯O and O-H⋯Br hydrogen bonds consolidate the structures.