Tris(piperazine-1,4-diium) bis[hexachloridoindate(III)] tetrahydrate

The asymmetric unit of the title compound, (C4H12N2)3[InCl6]2·4H2O, consists of one and half independent piperazinium cations, an hexachloridoindate anion and two molecules of water. The InIII ion is six-coordinated and forms a quasi-regular octahedral arrangement. In the crystal, alternating layers of cations and anions are arranged parallel to (10) and are linked with the water molecules via intra- and intermolecular N—H⋯O, O—H⋯Cl, C—H⋯O and N—H⋯Cl hydrogen bonds, forming a complex three-dimensional network. Additional stabilization within the layers is provided by weak intermolecular C—H⋯Cl interactions.

The asymmetric unit of the title compound, (C 4 H 12 N 2 ) 3 -[InCl 6 ] 2 Á4H 2 O, consists of one and half independent piperazinium cations, an hexachloridoindate anion and two molecules of water. The In III ion is six-coordinated and forms a quasi-regular octahedral arrangement. In the crystal, alternating layers of cations and anions are arranged parallel to (101) and are linked with the water molecules via intra-and intermolecular N-HÁ Á ÁO, O-HÁ Á ÁCl, C-HÁ Á ÁO and N-HÁ Á ÁCl hydrogen bonds, forming a complex three-dimensional network. Additional stabilization within the layers is provided by weak intermolecular C-HÁ Á ÁCl interactions.

Comment
The title compound, was prepared as part of our ongoing studies of hydrogen-bonding interactions in the crystal structures of protonated amines and imines (Bouacida, 2008;Bouacida et al., 2005;2007). We report here the synthesis and crystal structure of a new hybrid compound, (I).
The asymmetric unit of the title compound consists of one and half independent piperazinium cations, an hexachloridoindate anion and two molecules of water. The molecular structure of (I) is shown in Fig. 1. In the title compound, both imine N atoms of piperazine are protonated as in other related structures (Murugavel et al., 2009;Polishchuk et al., 2009).
These cations adopt typical chair conformation and alternate with hexachloridoindate complex forming layers parallel to the (10-1) plane (Fig 2).
The In III ion is six-coordinated and forms a quasi-regular octahedral arrangement (Fig 2). The crystal packing in (I) is governed by classical hydrogen bond, viz cation-anion, cation-cation, water-anion and cation-water (Table 1). In the crystal, the components of the structure are linked via intra and intermolecular N-H···O, O-H···Cl, C-H···O and N-H···Cl hydrogen bonds to form a complex three-dimensional network. Additional stabilization within these layers is provided by weak intermolecular C-H···Cl interactions (Fig. 3, Table 1).

Experimental
A solution of 1 mmol InCl 3 and 3 mmol piperazine in hydrochloric acid was slowly evaporated to dryness over a period of one week yielding colorless crystals suitable for X-ray diffraction.

Refinement
All H atoms were visible in differnce Fourier maps but were introduced in calculated positions and treated as riding on C and N atoms with C-H = 0.97 and N-H = 0.90 Å and U iso (H) = 1.2U eq (C/N/). The positions of water H atoms were refined with U iso (H) = 1.5 U eq (O). Fig. 1. The molecular structure of (I) with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are represented as small spheres of arbitrary radii. Symmetry code: (i) 1 -x, 1 -y, -z sup-2