Three-dimensional organic-inorganic hybrid sodium halide perovskite: C4H12N2•NaI3 and a hydrogen-bonded supramolecular three-dimensional network in 3C4H12N2•NaI4•3I•H2O

The rational selection of ligands is vitally important in the construction of new organic-inorganic hybrid three-dimensional perovskite complexes. As part of an exploration of perovskite-type materials, two new Na-I compounds based on the piperazine ligand, namely poly[piperazinediium [tri-mu-iodido-sodium]], {(C4H12N2)[NaI3]}(n), 1, and catena-poly[tris(piperazinediium) [[triiodidosodium]-mu-iodido] triiodide monohydrate], {(C4H12N2)(3)[NaI4]I-3 center dot H2O}(n), 2, have been synthesized by adjusting the stoichiometric ratio of sodium iodide and piperazine, and were characterized by single-crystal X-ray diffraction. In the crystal structures of 1 and 2, each Na-I cation is linked to six I atoms, but the compounds show completely different configurations. In 1, the structure includes a perovskite-like array of vertex-sharing NaI6 octahedra stretching along the direction of the three axes, and each piperazinediium dication is enclosed in the NaI3 perovskite cage. However, in 2, each Na-I atom bridges a single I atom to form a one-dimensional linear chain, and complex intermolecular hydrogen bonds connect these one-dimensional chains into a three-dimensional supramolecular network.