Bis(3-azaniumylpropyl)azanium hexachloridobismuthate(III) monohydrate

The asymmetric unit of the title compound, (C6H20N3)[BiCl6]·H2O, consists of a triprotonated bis(3-azaniumylpropyl)azanium cation, two halves of an octahedral [BiCl6]3− anion, each of the BiIII atoms lying on an inversion centre, and a water molecule. In the crystal, the anions and water molecules are linked by O—H⋯Cl hydrogen bonds, forming chains running parallel to [0-11]. The anionic chains and the cations are further linked into a three-dimensional network by N—H⋯Cl and N—H⋯O hydrogen-bond interactions.

The asymmetric unit of the title compound, (C 6 H 20 N 3 )-[BiCl 6 ]ÁH 2 O, consists of a triprotonated bis(3-azaniumylpropyl)azanium cation, two halves of an octahedral [BiCl 6 ] 3À anion, each of the Bi III atoms lying on an inversion centre, and a water molecule. In the crystal, the anions and water molecules are linked by O-HÁ Á ÁCl hydrogen bonds, forming chains running parallel to [011]. The anionic chains and the cations are further linked into a three-dimensional network by N-HÁ Á ÁCl and N-HÁ Á ÁO hydrogen-bond interactions.

Comment
This work is a part of our study on the crystal structure of alkylpolyammoniumbismuthate(III) chorides. This investigation was extended to aliphatic diamines of general formula NH 2 (CH 2 ) n NH 2 (Chaabouni et al., 1998;Rhandour et al., 2011;Ouasri et al., 2013) and triamines of general formula NH 2 (CH 2 ) n NH(CH 2 ) n NH 2 (Fu et al., 2005) in order to examine the effect of the flexible cation on the bismuth(III) coordination geometry. In these compounds the Bi atom shows a tendency toward distorted octahedral coordination with some rather long Bi-Cl bonds, which is attributed to the aspherical distribution of the lone pair electrons at Bi(III).
The asymmetric unit of the title compound contains one fully protonated bis(3-azaniumylpropyl)azanium cation, two half of a [BiCl 6 ] 3anion and a neutral water molecule. A perspective view of the arrangement of these constituent entities is shown in Fig. 1 together with the atom numbering scheme. Two slightly distorted [BiCl 6 ] 3octahedra are located in special position on an inversion centre. The Bi-Cl bond lengths vary from 2.6817 (8) to 2.7209 (8) Å with an average bond lengths of 2.7014 (8) Å. These values are much shorter than the sum of the van der Waal radii of Bi and Cl (4.7 Å) according to Pauling (Pauling, 1960). In addition to the bond length differences, the Cl-Bi-Cl angles for the Cl atoms in cis position with respect to each other fall in the range of 85.80 (3)-94.20 (3)°. It should be mentioned that the Cl-Bi -Cl bond angles deviate substantially from 90° by 4.2° for Bi(1) and 3.1° for Bi(2). By taking into account the sixth-fold coordination of bismuth atoms, we have proceeded to calculate the bond-valence sum (BVS) of this metal using the parameters given by Brown (Brown et al., 1985). The BVS calculation of the Bi1 and Bi2 ions gave respectively values of 3.23 and 3.38 valence units. These results confirm the presumed oxidation state of Bi(III). The distortion of the [BiCl 6 ] 3octahedral are correlated primary to the deformations resulting from the stereochemical activity of the Bi lone electron pair and secondary to deformations resulting from hydrogen bonding interactions The [BiCl 6 ] 3anions are connected through O-H···Cl hydrogen bonds (Table 1), so that [BiCl 6 (H 2 O)] n 3nchains spread one-dimensionally parallel to the [0 -1 1] direction. The unit cell is crossed by two centrosymmetrical [BiCl 6 (H 2 O)] n 3nchains with the (0 2 2) mid plane as shown in Fig. 2. The total negative charge (-3) on the framework is balanced by the presence of one independent fully protonated [NH 3 (CH 2 ) 3 NH 2 (CH 2 ) 3 NH 3 ] 3+ cation. The major contributions to the cohesion and the stability of the structure is provided by the presence of N-H···Cl and N-H···O hydrogen bonds linkages between the cations and the anionic chains belonging to adjacent (0 2 2) planes. All of these hydrogen bonds, N-H···Cl, N-H···O and O-H···Cl, give rise to a three-dimensional network in the structure ( Fig. 3 and Table 1).

Experimental
Crystals of the title compound were obtained by dissolving in 100 ml of a solution of HCl (12M) a stoichiometric mixture of bismuth(III) oxide and bis(3-amino-propyl)amine (molar ratio 1:2). The resulting aqueous solution was then kept at room temperature. After several weeks of slow evaporation at room temperature, prismatic shaped monocrystals of the title compound were obtained. They were washed with diethyl ether and dried for 4 h over CaCl 2 .

Refinement
All H atoms belonging to the organic group cation were geometrically positioned and treated as riding on their parent atoms, with C-H = 0.97 Å and N-H = 0.89-0.90 Å and with U iso (H) = 1.2 U eq (C, N). The water H atoms were located in a difference Fourier map and refined using DFIX and DANG restraints. Their bond lengths were set to ideal values of 0.85 Å and finally they were refined using a riding model with U iso (H) = 1.5 U eq (O).

Figure 1
A view of the asymmetric unit of the title compound with displacement ellipsoids drawn at the 50% probability level.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.