Crystal structure of catena-poly[bis-(N, O-di-methyl-hydroxyl-ammonium) [di-μ-bromido-di-bromido-stannate(II)]]

Abstract

The title compound, {(C₂H₈NO)₂[SnBr₄]} _n , is a layered hybrid perovskite crystallizing in the monoclinic space group C2/c. The asymmetric unit consists of one H₃C-O-NH₂ ⁺-CH₃ cation (Me₂HA⁺), one Sn^II atom located on a twofold rotation axis, and two Br atoms. The Sn^II atom has a distorted octa-hedral coordination environment formed by the bromido ligands. The {SnBr₆} units corner-share their equatorial Br atoms, forming infinite mono-layers that extend parallel to the ab plane. These inorganic layers are sandwiched by the organic Me₂HA⁺ cations organized in double-layers; stacking of the layers is along the c-axis direction. Consecutive inorganic layers, separated by the organic cations, are shifted relative to each other along the b-axis direction. Specifically, the Sn^II atom in one inorganic layer is offset by 3.148 Å along the b axis relative to the Sn^II atom in an adjacent inorganic layer. The N,O-di-methyl-hydroxyl-ammonium cation forms two hydrogen bonds with the axial bromide anions of the inorganic layers as acceptors, and leads to the cohesion of the crystal structure. According to Hirshfeld surface analysis, the highest contributions to the crystal packing are from H⋯H (46.2%), Br⋯H (38.5%), and H⋯O (14.8%) contacts.

Keywords: Hirshfeld surface analysis; N,O-di­methyl­hydroxyl­amine; crystal structure; metal halides; stannate; tin(II) bromide.

Figure 1

Representation of the building units in the crystal structure of compound (1), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are shown as small spheres of arbitrary radius. [Symmetry codes: (i)  + x,  + y, z; (ii) 1 − x, y,  − z; (iii)  − x,  + y,  − z.]

Figure 2

Projection of the crystal structure of (1) approximately along [110], showing its layered crystal structure.

Figure 3

Side view of a fragment of the crystal structure of (1), showing the orientation of organic cations and the hydrogen-bonding scheme (dotted lines). [Symmetry codes: (i) 1 − x, y,  − z; (ii)  − x,  + y,  − z; (iii) − + x, − + y, z.]

Figure 4

View along [001] of a fragment of inorganic layers in the crystal structure of (1). The upper inorganic layer is offset along the b axis relative to the adjacent inorganic layer (highlighted in green). In this projection, the distance between the Sn^II atom of the first inorganic layer is offset by 3.148 Å along the b axis relative to the adjacent layer. [Symmetry code: (i) x, 2 − y,  + z.]

Figure 5

(a) Hirshfeld surface representation with the function d_norm plotted onto the surface for the different inter­actions; two-dimensional fingerprint plots from a Hirshfeld surface analysis of (1) showing: (b) all contacts; (c) H⋯H (46.2%); (d) Br⋯H/H⋯Br (38.5%); (e) O⋯H/H⋯O (14.8%); (f) O⋯O (0.3%); (g) Br⋯O/O⋯Br (0.1%) and (h) Sn⋯H/H⋯Sn (0.1%).