Bis(2,6-diamino-3,5-dibromo­pyridinium) hexa­bromidostannate(IV)

Rawhi H Al-Far; Salim F Haddad; Basem Fares Ali

doi:10.1107/S1600536809015189

. 2009 Apr 30;65(Pt 5):m583–m584. doi: 10.1107/S1600536809015189

Bis(2,6-diamino-3,5-dibromopyridinium) hexabromidostannate(IV)

Rawhi H Al-Far ^a, Salim F Haddad ^b, Basem Fares Ali ^c,^*

PMCID: PMC2977624 PMID: 21583810

Abstract

The asymmetric unit of the title compound, (C₅H₆Br₂N₃)₂[SnBr₆], contains one cation and one half-anion in which the Sn atom is located on a crystallographic centre of inversion and is in a quasi-octahedral geometry. The crystal structure is assembled via hydrogen-bonding interactions of two kinds, N(pyridine/amine)—H⋯Br—Sn, along with C—Br⋯Br—Sn interactions [3.4925 (19) Å]. The cations are involved in π–π stacking, which adds an extra supramolecularity as it presents a strong case of offset-face-to-face motifs [centroid–centroid distance = 3.577 (3) Å]. The intermolecular hydrogen bonds, short Br⋯Br interactions and π–π stacking result in the formation of a three-dimensional supramolecular architecture.

Related literature

For general background to hybrid organic–inorganic compounds, see: Aruta et al. (2005 ▶); Hill (1998 ▶); Kagan et al. (1999 ▶); Knutson et al. (2005 ▶); Raptopoulou et al. (2002 ▶). For related structures, see: Al-Far & Ali (2007 ▶); Al-Far, Ali & Al-Sou’od (2007 ▶); Ali & Al-Far (2007 ▶); Ali et al. (2008 ▶); Ali, Al-Far & Ng (2007 ▶); Awwadi et al. (2007 ▶); Tudela & Khan (1991 ▶); Willey et al. (1998 ▶). For bond-length data, see: Allen et al. (1987 ▶).

Experimental

Crystal data

(C₅H₆Br₂N₃)₂[SnBr₆]
M _r = 1133.97
Monoclinic,
a = 8.3696 (14) Å
b = 16.720 (2) Å
c = 9.5814 (15) Å
β = 112.556 (12)°
V = 1238.3 (3) Å³
Z = 2
Mo Kα radiation
μ = 17.18 mm⁻¹
T = 295 K
0.30 × 0.30 × 0.20 mm

Data collection

Bruker P4 diffractometer
Absorption correction: ψ scan (XSCANS; Bruker, 1996 ▶) T _min = 0.007, T _max = 0.035
2825 measured reflections
2162 independent reflections
1437 reflections with I > 2σ(I)
R _int = 0.078
3 standard reflections every 97 reflections intensity decay: 0.01%

Refinement

R[F ² > 2σ(F ²)] = 0.059
wR(F ²) = 0.146
S = 1.00
2162 reflections
124 parameters
H-atom parameters constrained
Δρ_max = 0.97 e Å⁻³
Δρ_min = −1.63 e Å⁻³

Data collection: XSCANS (Bruker, 1996 ▶); cell refinement: XSCANS; data reduction: SHELXTL (Sheldrick, 2008 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809015189/hk2669sup1.cif

e-65-0m583-sup1.cif^{(15.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809015189/hk2669Isup2.hkl

e-65-0m583-Isup2.hkl^{(106.3KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected geometric parameters (Å, °).

Sn1—Br1	2.6002 (13)
Sn1—Br2	2.5768 (14)
Sn1—Br3	2.6131 (14)

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Symmetry code: (i) Inline graphic .

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯Br3ⁱⁱ	0.86	2.54	3.354 (9)	159
N2—H2B⋯Br3ⁱⁱ	0.86	2.88	3.612 (12)	144
N3—H3A⋯Br2ⁱⁱ	0.86	2.79	3.608 (10)	160
N3—H3B⋯Br1ⁱⁱⁱ	0.86	2.82	3.604 (10)	153

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Symmetry codes: (ii) Inline graphic ; (iii) .

Acknowledgments

The University of Jordan, Al-Balqa’a Applied University and Al al-Bayt University are thanked for financial support.

supplementary crystallographic information

Comment

Non-covalent interactions play an important role in organizing structural units in both natural and artificial systems. Hybrid organic-inorganic compounds are of great interest owing to their ionic, electrical, magnetic and optical properties (Hill, 1998; Kagan et al., 1999; Raptopoulou et al., 2002). Tin metal-halo based hybrids are of particular interest as being materials with interesting optical and magnetic properties (Aruta et al., 2005; Knutson et al., 2005; Kagan et al., 1999). We are currently carrying out studies about lattice including different types of intermolecular interactions (aryl···aryl, X···X, X···aryl and X···H). Within our research of hybrid compounds containing tin metal (Al-Far & Ali 2007; Al-Far, Ali & Al-Sou'od, 2007; Ali & Al-Far, 2007; Ali, Al-Far & Ng, 2007), we report herein the crystal structure of the title compound.

The asymmetric unit of the title compound contains one cation and one-half anion, in which the Sn atom is located on a crystallographic centre of inversion and is in a quasi-octahedral geometry (Fig. 1 and Table 1). The Sn-Br bonds are in accordance with the corresponding values in similar compounds (Willey et al., 1998; Tudela & Khan 1991; Ali et al., 2008; Al-Far & Ali 2007). The pyridine ring of the starting cation have undergone bromination during the synthesis process (Al-Far & Ali, 2007). In the cation, the bond lengths (Allen et al., 1987) and angles are within normal ranges.

In the crystal structure, weak intermolecular N-H···Br interactions (Table 2) link the molecules into alternating layers of cations and stacks of anions (Fig. 2), in which they may be effective in the stabilization of the structure. The anion stacks are interacting with the cation layers in an extensive hydrogen bonding and Br···Br halogen bonding interactions. Each anion is surrounded by six cations via three H—N—H···Br, one N—H···Br interactions and the symmetry related ones along with one Br···Br interaction [Br2···Br4ⁱ = 3.4925 (19) Å, symmetry code (i): 2 - x, 1 - y, -z)] and the symmetry related one. On the other hand, each cation is associated with three anions, through six (N_pyridinic, N_aminic)—H···Br—Sn hydrogen bonding interactions, and by one C—Br···Br—Sn interaction. It is noteworthy that structural and theoretical results (Awwadi et al. 2007; and references therein), show the significance of linear C—Br···Br synthons in influencing structures of crystalline materials and in use as potential building blocks in crystal engineering via supramolecular synthesis.

Moreover, interactions between cations perpendicular to [101] represent a case of strong offset face-to-face π–π motif. This is evident by the centroids separation distance of 5.059 (3) Å, with the perpendicular distance between planes being 3.577 (3) Å (the sliding angle between planes is 45.0 (3)°).

Experimental

For the preparation of the title compound, the warm solution of SnCl₂ metal (1.0 mmol) dissolved in absolute ethanol (15 ml) was mixed with a stirred hot solution of 2,6-diaminopyridine (98%; 2 mmol) dissolved in ethanol (20 ml). The mixture was acidified with HBr (48%, 2-3 ml), and then treated with liquid Br₂ (2-3 ml). The resulting mixture was stirred for 3 h, and then allowed to evaporate at room temperature. The salt crystallized over 2 d, as nice parallelepiped yellow crystals (yield; 82%).