The one-dimensional organic–inorganic hybrid: catena-poly[bis[1-(3-ammoniopropyl)-1H-imidazolium] [[iodidoplumbate(II)]-tri-μ-iodido-plumbate(II)-tri-μ-iodido-[iodidoplumbate(II)]-di-μ-iodido]]

The organic–inorganic hybrid, {(C6H13N3)2[Pb3I10]}n, was obtained by the reaction of 1-(3-ammoniopropyl)imidazolium triiodide and PbI2 at room temperature. The structure contains one-dimensional {[Pb3I10]4−}n polymeric anions spreading parallel to [001], resulting from face–face–edge association of PbI6 distorted octahedra. One of the PbII cations is imposed at an inversion centre, whereas the second occupies a general position. N—H⋯I hydrogen bonds connect the organic cations and inorganic anions.

The organic-inorganic hybrid, {(C 6 H 13 N 3 ) 2 [Pb 3 I 10 ]} n , was obtained by the reaction of 1-(3-ammoniopropyl)imidazolium triiodide and PbI 2 at room temperature. The structure contains one-dimensional {[Pb 3 I 10 ] 4À } n polymeric anions spreading parallel to [001], resulting from face-face-edge association of PbI 6 distorted octahedra. One of the Pb II cations is imposed at an inversion centre, whereas the second occupies a general position. N-HÁ Á ÁI hydrogen bonds connect the organic cations and inorganic anions.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: YK2002). metal-organic compounds m458 Trigui et al.

Comment
Recently, self-assembling organic-inorganic hybrid compounds have been the focus of a great number of investigations owing to their unique structural, magnetic, optical nonlinear and optoelectronic functionality (Papavassiliou et al., 1999;Ishihara et al., 1990;Mitzi et al., 2001). In particular, the lead iodide-based hybrid materials have been extensively studied (Gebauer & Schmid, 1999;Dammak et al., 2009;Elleuch et al., 2010) since they show strong room temperature excitonic optical features with large exciton binding energy and oscillator strengths. These low dimensional complexes include zero dimensional (0D), one dimensional (1D), and two dimensional (2D) lead iodide networks with organic groups as spacers.
Among them, 1D-hybrids are more attractive in nanoscaled applications since they form a variety of crystalline structures, which differ in the inorganic chain where the [PbI 6 ] octahedra can be connected in different ways: face sharing (Elleuch et al., 2007), edge sharing (Samet Kallel et al., 2008), corner sharing (Mousdis et al., 1998) or through several combinations of these various types of sharing (Maxcy et al., 2003;Billing & Lemmerer, 2004;Krautscheid et al., 2001), as in the case of our compound. We present here the structure of the organic-inorganic one dimensional hybrid compound (C 6 H 13 N 3 ) 2 Pb 3 I 10 .
The crystal structure of the title compound consists of (Pb 3 I 10 ) n 4nchains extending along [001] with the 1-(3-ammoniopropyl)-imidazolium cations as counter-ions (Fig. 1). The inorganic anion, shown in Fig. 1, can be considered as a set of mixed face-shared/edge-shared octahedra. In fact, the unit cell contains three octahedra with two crystallographically independent Pb atoms: Pb1 and Pb2. The central Pb2 octahedron is connected to the Pb1 octahedra by shared faces, while the Pb1 octahedra are linked via edge-sharing at both ends of Pb 3 I 10 4to adjacent units.
The coordination octahedron of the central lead ion Pb2 is only slightly distorted since it is located on an inversion centre and is bound to three unique I atoms: I2, I3 and I4, which participate in the face-sharing between the Pb2 and Pb1 octahedra.
The bond lengths around Pb2 are very similar (3.2105 (15), 3.2388 (14), 3.263 (2) Å), the bond angles I-Pb2-I deviate slightly from ideal octahedral values, ranging from 83° to 94°. In contrast, Pb1 has a more distorted environement with Pb-I distances ranging from 3.155 (2) to 3.309 (2) Å and with all cis and trans angles different (see Table 1). This Pb atom is bonded to five unique I atoms, where two I1 atoms are responsible for the edge sharing between the neighbouring units to form one-dimensional infinite chains. Atom I5 is the only halide not involved in any bonding with adjacent octahedra and has the shortest Pb-I distance [3.155 (2) Å].
Cations fill channels between the anionic chains (Fig.2). Each terminal ammonium group forms three N-H···I hydrogen bonds to I atoms of three different chains (see Table 2).
supplementary materials sup-2 Experimental Single crystals of (C 6 H 13 N 3 ) 2 Pb 3 I 10 were grown by the slow evaporation at room temperature of a solution containing PbI 2 and C 6 H 13 N 3 I 3 salts. An aqueous solution of HI was added to the aminopropylimidazole to synthesize C 6 H 13 N 3 I 3 precursor. Under ambient conditions, stoechiometric amounts of C 6 H 13 N 3 I 3 and PbI 2 with excess HI were sailed in DMF.
This mixture was stirred and remained clear without any precipitate. Pale-yellow flatted crystals were obtained few weeks later. Supplementary data for this paper are available from the IUCr electronic archives (Reference: CCDC 782074).

Refinement
All H atoms attached to C and N atom were fixed geometrically and treated as riding with C-H = 0.97 Å (CH 2 ) or 0.93 Å (CH) and N-H = 0.89 Å (NH 3 ) or 0.86 Å (NH) with U iso (H) = 1.2U eq (C or N). Fig. 1. View of the asymmetric unit of (C 6 H 13 N 3 ) 2 Pb 3 I 10 with some adjacent atoms showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level.