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-methylpiperizine-1,4-diium [tri-mu-bromido-potassium] hemihydrate], {(C5H14-N-2)[KBr3]center dot 0.5H(2)O}(n), (I), poly[1-methylpiperizine-1,4-diium [tri-mu-bromido-rubidium] hemihydrate], {(C5H14N2)[RbBr3]center dot 0.5H(2)O}(n), (II), and poly[1-methyl-piperizine-1,4-diium [tri-mu-bromido-caesium] hemihydrate], {(C5H14N2)[CsBr3]center dot 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 C5H14N22+ cations occupy interstices bounded by eight octahedra and the water molecules lie in square sites bounded by four octahedra. N-H center dot center dot center dot Br, N-H center dot center dot center dot(Br,Br), N-H center dot center dot center dot O and O-H center dot center dot center dot Br hydrogen bonds consolidate the structures.