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Acta Cryst. (2012). E68, o2786    [ doi:10.1107/S1600536812036136 ]

2-Amino-5-methylpyridinium dibromoiodate

S. F. Haddad, B. F. Ali and R. Al-Far

Abstract top

In the title salt, C6H9N2+·Br2I-, the cation is essentially planar (r.m.s. deviation = 0.0062 Å for the non-H atoms) while the anion is almost linear with a Br-I-Br angle of 177.67 (2)°. The crystal packing shows two anions and two cations connected via N-H...Br and (pyridine)N-H...Br hydrogen-bonding interactions, forming centrosymmetric tetramers with R44(16) ring motifs. Very weak offset aromatic [pi]-[pi] stacking interactions [centroid-centroid separation = 4.038 (4), slippage = 1.773 Å] also occur.

Comment top

Polyhalides display a variety of structures. Various compounds with interesting structures were found when protonated aromatic nitrogen bases were combined with polyhalides (Kochel, 2006). Continuing our research in this area (Al-Far et al., 2012), we now report the crystal structure of the title compound in this article. The cystals of the title compound were found as an unexpected product from a reaction mixture of CdI2, HBr, 2-amino-5-methylpyridine and Br2 upon attempting to synthesize [(C7H10N)]2 [CdBr4] complex of 2-amino-5-methylpyrinium.

In the title compound (Fig. 1), the cation, 2-amino-5-methylpyridinium, is essentially planar (r.m.s.d = 0.0062 Å). The IBr2- anion is symmetrical and almost linear, Br1—I—Br2 angle of 177.67 (2) °, with I—Br distances 2.6836 (10) and 2.7119 (10) Å. These values are in agreement with the values reported in the literature (Gardberg et al., 2002). The molecular dimensions of the cation are also as expected (Hemamalini & Fun, 2010).

The crystal structure (Fig. 2), shows stacks of anions separated by layers of cations. The anions and cations are connected via H–N–H···Br and pyN–H···Br hydrogen bonding (Table 1), forming centrosymmetric tetramers (two cation and two anions). These tetramers form sixteen membered rings in graph set motif R44(16) (Bernstein et al., 1995). The rings are further connected via π···π interactions between the cations with separation betweeen the ring centroids [Cg···Cg (2 - x, -y, 1 - z)] being 4.038 (4) Å. Both hydrogen bonding and π···π interactions consolidate a three dimensional network.

Related literature top

For background to this study, see: Al-Far et al. (2012); Kochel (2006). For comparison bond lengths and angles, see: Gardberg et al. (2002); Hemamalini & Fun (2010). For graph-set notation, see: Bernstein et al. (1995).

Experimental top

A solution of CdI2 (0.37 g, 1.0 mmol) dissolved in 95% EtOH (10 ml) and 60% HBr (1 ml) solution was added to a mixture of 2-amino-5-methylpyridine (0.11 g, 1.0 mmol) dissolved in 95% EtOH (10 ml), 60% HBr (1 ml) and molecular bromine (2 ml). The resulting mixture was refluxed for 2.5 hr. On slow evaporation at room temperature yellow plates of the title compound were formed in 4 days (yield 85%).

Refinement top

All H atoms were positioned geometrically and refined using a riding model, with N—H = 0.86 Å and C—H = 0.93 and 0.96 Å, for aryl and methyl H-atoms, respectively. The Uiso(H) were allowed at 1.5Ueq(C methyl) or 1.2Ueq(N/C non-methyl).

Computing details top

Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO (Agilent, 2011); data reduction: CrysAlis PRO (Agilent, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms are presented as small spheres of arbitrary radius.
[Figure 2] Fig. 2. A view of the pyN–H···Br and H–N–H···Br hydrogen bonds (dotted lines) in the crystal structure of the title compound. H atoms non-participating in hydrogen-bonding were omitted for clarity.
2-Amino-5-methylpyridinium dibromoiodate top
Crystal data top
C6H9N2+·Br2IZ = 2
Mr = 395.85F(000) = 364
Triclinic, P1Dx = 2.422 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 8.3648 (13) ÅCell parameters from 1406 reflections
b = 8.4233 (16) Åθ = 3.2–30.0°
c = 9.2321 (16) ŵ = 10.26 mm1
α = 105.107 (16)°T = 293 K
β = 115.371 (16)°Plate, yellow
γ = 98.241 (15)°0.54 × 0.39 × 0.30 mm
V = 542.7 (2) Å3
Data collection top
Agilent Xcalibur Eos
diffractometer
2465 independent reflections
Radiation source: Enhance (Mo) X-ray Source1777 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.029
Detector resolution: 16.0534 pixels mm-1θmax = 29.1°, θmin = 3.2°
ω scansh = 1110
Absorption correction: multi-scan
(CrysAlis PRO; Agilent, 2011)
k = 1111
Tmin = 0.011, Tmax = 0.045l = 1012
4283 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.040H-atom parameters constrained
wR(F2) = 0.096 w = 1/[σ2(Fo2) + (0.035P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.01(Δ/σ)max < 0.001
2465 reflectionsΔρmax = 1.17 e Å3
102 parametersΔρmin = 0.85 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0292 (12)
Crystal data top
C6H9N2+·Br2Iγ = 98.241 (15)°
Mr = 395.85V = 542.7 (2) Å3
Triclinic, P1Z = 2
a = 8.3648 (13) ÅMo Kα radiation
b = 8.4233 (16) ŵ = 10.26 mm1
c = 9.2321 (16) ÅT = 293 K
α = 105.107 (16)°0.54 × 0.39 × 0.30 mm
β = 115.371 (16)°
Data collection top
Agilent Xcalibur Eos
diffractometer
2465 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Agilent, 2011)
1777 reflections with I > 2σ(I)
Tmin = 0.011, Tmax = 0.045Rint = 0.029
4283 measured reflectionsθmax = 29.1°
Refinement top
R[F2 > 2σ(F2)] = 0.040H-atom parameters constrained
wR(F2) = 0.096Δρmax = 1.17 e Å3
S = 1.01Δρmin = 0.85 e Å3
2465 reflectionsAbsolute structure: ?
102 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

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 F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
N11.0416 (7)0.3049 (7)0.7106 (6)0.0606 (15)
H1A1.03870.33310.80570.073*
I10.70649 (5)0.04784 (5)0.90281 (5)0.04214 (17)
Br10.55742 (10)0.38624 (9)0.80942 (10)0.0661 (2)
N20.7745 (7)0.3836 (7)0.5894 (7)0.0699 (17)
H2A0.77510.41210.68620.084*
H2B0.68820.39470.50210.084*
C20.9069 (8)0.3223 (8)0.5748 (8)0.0509 (16)
Br20.85761 (10)0.29148 (9)0.98508 (9)0.0589 (2)
C30.9133 (8)0.2686 (8)0.4207 (8)0.0500 (15)
H3A0.82240.27490.32110.060*
C41.0533 (8)0.2076 (9)0.4194 (8)0.0551 (17)
H4A1.05620.17280.31660.066*
C51.1936 (8)0.1936 (8)0.5625 (7)0.0438 (14)
C61.1819 (9)0.2455 (9)0.7061 (9)0.0591 (18)
H6A1.27320.24060.80640.071*
C71.3488 (8)0.1264 (9)0.5598 (9)0.0647 (19)
H7A1.43290.13350.67340.097*
H7B1.41300.19380.52110.097*
H7C1.29990.00870.48300.097*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.077 (4)0.061 (4)0.032 (3)0.007 (3)0.025 (3)0.008 (3)
I10.0468 (3)0.0479 (3)0.0301 (2)0.01598 (19)0.01656 (19)0.01427 (19)
Br10.0739 (5)0.0464 (4)0.0580 (5)0.0088 (4)0.0210 (4)0.0132 (4)
N20.076 (4)0.076 (5)0.060 (4)0.019 (3)0.039 (3)0.019 (4)
C20.052 (3)0.050 (4)0.046 (4)0.002 (3)0.023 (3)0.018 (3)
Br20.0794 (5)0.0461 (4)0.0465 (4)0.0117 (4)0.0284 (4)0.0173 (4)
C30.054 (4)0.054 (4)0.038 (4)0.011 (3)0.023 (3)0.014 (3)
C40.062 (4)0.058 (4)0.041 (4)0.008 (3)0.026 (3)0.014 (3)
C50.049 (3)0.042 (4)0.031 (3)0.005 (3)0.013 (3)0.015 (3)
C60.060 (4)0.064 (5)0.040 (4)0.013 (4)0.016 (3)0.016 (4)
C70.063 (4)0.069 (5)0.057 (5)0.022 (4)0.023 (4)0.025 (4)
Geometric parameters (Å, º) top
N1—C21.340 (7)C3—H3A0.9300
N1—C61.352 (8)C4—C51.389 (8)
N1—H1A0.8600C4—H4A0.9300
I1—Br12.6836 (10)C5—C61.334 (8)
I1—Br22.7119 (10)C5—C71.496 (8)
N2—C21.330 (7)C6—H6A0.9300
N2—H2A0.8600C7—H7A0.9600
N2—H2B0.8600C7—H7B0.9600
C2—C31.402 (8)C7—H7C0.9600
C3—C41.348 (8)
C2—N1—C6123.5 (5)C3—C4—H4A118.0
C2—N1—H1A118.3C5—C4—H4A118.0
C6—N1—H1A118.3C6—C5—C4115.2 (6)
Br1—I1—Br2177.67 (2)C6—C5—C7121.3 (6)
C2—N2—H2A120.0C4—C5—C7123.5 (5)
C2—N2—H2B120.0C5—C6—N1122.1 (6)
H2A—N2—H2B120.0C5—C6—H6A118.9
N2—C2—N1120.1 (6)N1—C6—H6A118.9
N2—C2—C3123.6 (6)C5—C7—H7A109.5
N1—C2—C3116.3 (6)C5—C7—H7B109.5
C4—C3—C2118.9 (6)H7A—C7—H7B109.5
C4—C3—H3A120.5C5—C7—H7C109.5
C2—C3—H3A120.5H7A—C7—H7C109.5
C3—C4—C5123.9 (6)H7B—C7—H7C109.5
C6—N1—C2—N2179.2 (6)C3—C4—C5—C60.0 (10)
C6—N1—C2—C32.4 (9)C3—C4—C5—C7179.7 (6)
N2—C2—C3—C4179.7 (6)C4—C5—C6—N11.0 (10)
N1—C2—C3—C41.4 (9)C7—C5—C6—N1179.3 (6)
C2—C3—C4—C50.3 (10)C2—N1—C6—C52.3 (10)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···Br20.862.733.499 (5)150
N2—H2B···Br1i0.862.703.545 (6)168
Symmetry code: (i) x+1, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···Br20.862.733.499 (5)149.5
N2—H2B···Br1i0.862.703.545 (6)168.0
Symmetry code: (i) x+1, y, z+1.
Acknowledgements top

The structure was determined at the Hamdi Mango Center for Scientific Research at the University of Jordan.

references
References top

Agilent (2011). CrysAlis PRO. Agilent Technologies, Yarnton, England.

Al-Far, W., Ali, B. F. & Haddad, S. F. (2012). Acta Cryst. E68, o2743.

Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N. L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573.

Gardberg, A. S., Yang, S., Hoffman, B. M. & Ibers, J. A. (2002). Inorg. Chem. 41, 1778–1781.

Hemamalini, M. & Fun, H.-K. (2010). Acta Cryst. E66, o2192–o2193.

Kochel, A. (2006). Acta Cryst. E62, o5605–o5606.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.