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

Abstract

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-μ-iodido-sodium]], {(C₄H₁₂N₂)[NaI₃]}_n, 1, and catena-poly[tris(piperazinediium) [[triiodidosodium]-μ-iodido] triiodide monohydrate], {(C₄H₁₂N₂)₃[NaI₄]I₃·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.

Keywords: crystal structure; hydrogen bonds; iodide; organic–inorganic hybrid; sodium halides; three-dimensional perovskite.

Figure 1

A view of the asymmetric unit in compound 1. All H atoms have been omitted for clarity. [Symmetry codes: (i) −x + 1, −y + 2, −z + 1; (ii) x − , y + , z; (iii) −x + 1, −y + 1, −z + 1; (iv) −x + 1, y, −z + ; (v) x + , y − , z; (vi) −x + , y − , −z + .]

Figure 2

(a) A view of the three-dimensional perovskite cage of C₄H₁₂N₂·KCl₃·H₂O. (b) A view of the three-dimensional perovskite cage of compound 1.

Figure 3

The hydrogen bonds (dashed lines) in 1 of the C and N atoms of the piperazinediium cation with the I atoms of the NaI₆ octa­hedra. [Symmetry codes: (i) −x + 1, −y + 2, −z + 1; (ii) x − , y + , z; (iv) −x + 1, y, −z + ; (vii) −x + , −y + , −z + 1; (viii) x + , −y + , z + .]

Figure 4

A packing view of compound 1, showing the three-dimensional perovskite structure.

Figure 5

A view of the asymmetric unit in compound 2. All H atoms have been omitted for clarity. [Symmetry codes: (i) x − , −y + , z − ; (ii) x + , −y + , z + .]

Figure 6

A partial view of the crystal packing of compound 2, showing the inter­molecular N—H⋯I (blee and yellow dashed lines), N—H⋯O (red dashed lines) and O—H⋯I (green dashed lines) hydrogen bonds. All H atoms on C atoms have been omitted for clarity. [Symmetry codes: (i) x − 2, y, z; (ii) −x − , y + , −z + ; (iii) −x, −y + 2, −z + 1; (iv) −x − 1, −y + 1, −z + 1; (v) x − , −y + , −z + ; (vi) x − 2, y + 1, z; (vii) −x − , y + , −z + ; (viii) x − , −y + , z − ; (ix) −x − 1, −y + 1, −z + 1; (x) −x − , y + , −z + ; (xi) x − , −y + , z − ; (xii) x − 2, y + 1, z; (xiii) x − , −y + , z + .]

Figure 7

The hydrogen bonds of the O—H⋯I (green dashed lines) and N—H⋯O (red dashed lines) types in 2, showing the two-dimensional network on the ac plane.

Figure 8

A packing view of compound 2, showing the three-dimensional hydrogen-bonded network.