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hg5319 scheme

Acta Cryst. (2013). E69, o1060-o1061    [ doi:10.1107/S1600536813015389 ]

2-Aminopyridin-1-ium triiodide

G. J. Reiss and P. B. Leske

Abstract top

The asymmetric unit of the title compound, C5H7N2+.I3-, consists of one 2-aminopyridin-1-ium cation (apyH+) and one triiodide anion, both located in general postions. The apyH+ cation is planar within the experimental uncertainties. The short N-C distance [1.328 (5) Å] of the exocyclic NH2 group is typical for the imino-form of protonated 2-aminopyridines. Consequently, the bond lengths within the six-membered ring vary significantly. The geometric parameters of the triiodide anion are in the typical range, with bond lengths of 2.8966 (3) and 2.9389 (3) Å and a bond angle of 176.02 (1)°. In the crystal, N-H ... I hydrogen bonds connect adjacent ions into screwed chains along the b-axis direction. These chains are twisted pairwise into rectangular rods. The pyridinium moieties of neighbouring rods are arranged parallel to each other with a plane-to-plane distance of 3.423 (5) Å.

Comment top

Aminopyridines are of general interest as they show biological activity (Bolliger et al., 2011). Especially the monoprotonated cations are able to inactivate K+ channels reversibly (Muñoz-Caro & Niño, 2002). Another field of research related to 2-aminopyridinium salts is focused on their nonlinear optical properties (Srinivasan & Priolkar, 2013; Shkir, et al., 2012; Periyasamy et al., 2007). There are more than one hundred mono-protonated 2-aminopyridin-1-ium cations (apyH+) listed in the Cambridge Structural Database. Common to all is the protonation at the ring-nitrogen atom. Moreover, a short exocyclic C—N bond is typically for this cation which represents the so-called imino-form (Scheme 1). The electronic consequences of the mono-protonation of 2-Aminopyridine (Chai et al., 2009; Testa & Wild, 1981) and the electronic structure of the resulting apyH+ monocation (Chapkanov, 2010) seem to be well understood. This contribution is part of our ongoing general interest in the hydrogen bonding of polyiodide salts (Reiss & Engel, 2002; Reiss & Engel, 2004; Meyer et al., 2010). This applies in particular to the structural chemistry of aromatic nitrogen-containing polyiodide salts (Reiss & van Megen, 2012a).

The asymmetric unit of the title structure consists of one 2-aminopyridin-1-ium cation and one I3- anion both located in general positions (Fig. 1). The geometric parameters of the apyH+ cation are in accord with the imino-form of a protonated 2-aminopyridine. The C–C and C–N bond lengths within the ring show C–N distances of 1.353 (5) and 1.354 (5) Å and C—C bond lengths ranging from 1.355 (5) to 1.411 (5) Å. The exocyclic C–N bond length is with 1.328 (5) Å very short, thus in the expected range for the imino-form of a protonated aminopyridine. Bond valence calculations for the apyH+ cation were performed using Brown's empirical method (Brown, 2009). The three different C–N bond lengths correspond to bond orders of 1.27 to 1.36, whereas the bond orders of the C–C bonds vary between 1.42 and 1.65 (Scheme 1). The geometric parameters of the triiodide anion are also in the typical range for a hydrogen bonded triiodide anion (e.g. van Megen & Reiss, 2012) with bond lengths of 2.8966 (3) and 2.9389 (3) Å and a bond angle of 176.02 (1)°. The Raman spectrum shows two intense signals at 126 and 115 cm-1 and a medium strong signal at 73 cm-1 which all are in excellent accord with the geometric parameters of the triiodide anion of the title structure and literature known examples (Deplano et al., 1999). The Raman and the infrared spectrum show a vast number of bands from 4000 to 400 cm-1 which are in the expected ranges for the apyH+ monocation (Çırak, 2011; Fig. 2).

Cations and anions are connected by N–H ··· I hydrogen bonds. Each cation donates three un-bifurcated hydrogen bonds by the three hydrogen atoms attached to nitrogen atoms to two adjacent triiodide anions (Fig. 1). By these connections chains along the b direction are formed (Fig. 3). The hydrogen bonded chains are twisted pairwise to rectangular rods. These double chains (rods) (Fig. 3 and 4) are connected to adjacent ones by pyridine-pyridine interactions which are arranged in parallel with a plane to plane distance of 3.423 Å. This value is in excellent agreement with the results of ab initio calculations reported recently (Ninković et al., 2012). In general, π-π interactions of pyridine moieties may play an important role in the biological system (Berl et al., 2000) and are of significant interest in the structural chemistry of metal complexes with aromatic nitrogen-containing ligands (Janiak, 2000).

Related literature top

For the biological activity of aminopyridines, see: Bolliger et al. (2011); Muñoz-Caro & Niño (2002). For aminopyridinium salts with non-linear optical properties, see: Srinivasan & Priolkar (2013); Shkir et al. (2012); Periyasamy et al. (2007). For the spectroscopy of aminopyridinium salts, see: Çırak et al. (2011). For bond-order calculations, see: Brown (2009). For the protonation and electronic structure of 2 amiopyridin-1-ium cations, see: Chapkanov (2010); Chai et al. (2009); Testa & Wild (1981). For the spectroscopy of polyiodides, see: Deplano et al. (1999). For pyridine–pyridine interactions, see: Ninković et al. (2012); Berl et al. (2000); Janiak (2000). For related poliodides, see: van Megen & Reiss (2012); Reiss & van Megen (2012a,b); Meyer et al. (2010); Reiss & Engel (2002, 2004). For the elemental analysis of polyiodides, see: Reiss & van Megen (2012b\bbr9 021); Egli (1969).

Experimental top

2-Aminopyridine (0.16 g; 1.7 mmol) was dissolved in 10 ml concentrated hydroiodic acid yielding a brown mixture. This mixture was heated to 90 °C and then slowly cooled to room temperature. Within 12 h needle-shaped, orange crystals grew from this solution. Elemental analysis (C5H7N2I3): calcd., %: C, 12.62; H, 1.48; N, 5.89; I, 80.01. Found, %: C, 12.07; H, 1.45; N, 5.60; I, 79.44. For details on the elemental analytical methods used, see: Reiss & van Megen (2012b); Egli (1969).

Refinement top

The coordinates of all hydrogen atoms were refined. The N-H distances were restrained to 0.85 (1) Å. It was possible to introduce individual Uiso values for the hydrogen atoms attached to nitrogen atoms, whereas for carbon bound hydrogen atoms Uiso values had to be set to 1.2Ueq(C).

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS2013 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2012); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. Showing the asymmetric unit of the title structure (Displacement ellipsoids are drawn at the 50% probability level).
[Figure 2] Fig. 2. Shows the infrared spectrum (upper part) and Raman spectrum (lower part) of the title compound.
[Figure 3] Fig. 3. Pairwise twisted (green/violet and red/blue) hydrogen bonded chains run along [010].
[Figure 4] Fig. 4. Showing the packing of rectangular rods constructed by pairwise twisted chains. π-π interactions are visualized by black lines connecting the centres of neighbouring rings.
2-Aminopyridin-1-ium triiodide top
Crystal data top
C5H7N2+·I3Z = 2
Mr = 475.83F(000) = 420
Triclinic, P1Dx = 2.929 Mg m3
a = 8.0446 (4) ÅMo Kα radiation, λ = 0.71073 Å
b = 8.9973 (5) ÅCell parameters from 6254 reflections
c = 9.1464 (4) Åθ = 3.1–32.6°
α = 117.805 (6)°µ = 8.64 mm1
β = 90.939 (4)°T = 100 K
γ = 109.640 (5)°Plate, orange
V = 539.46 (6) Å30.43 × 0.41 × 0.04 mm
Data collection top
Oxford Diffraction Xcalibur Eos
diffractometer
2186 independent reflections
Radiation source: Sealed tube X-ray Source2078 reflections with I > 2σ(I)
Equatorial mounted graphite monochromatorRint = 0.021
Detector resolution: 16.2711 pixels mm-1θmax = 26.3°, θmin = 3.1°
ω scansh = 109
Absorption correction: analytical
[CrysAlis PRO (Oxford Diffraction, 2009) based on expressions derived by Clark & Reid (1995)]
k = 1111
Tmin = 0.083, Tmax = 0.698l = 1111
5668 measured reflections
Refinement top
Refinement on F2Hydrogen site location: difference Fourier map
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.018 w = 1/[σ2(Fo2) + (0.015P)2 + 1.5P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.041(Δ/σ)max = 0.001
S = 1.01Δρmax = 0.99 e Å3
2186 reflectionsΔρmin = 0.59 e Å3
117 parametersExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
2 restraintsExtinction coefficient: 0.0075 (2)
Crystal data top
C5H7N2+·I3γ = 109.640 (5)°
Mr = 475.83V = 539.46 (6) Å3
Triclinic, P1Z = 2
a = 8.0446 (4) ÅMo Kα radiation
b = 8.9973 (5) ŵ = 8.64 mm1
c = 9.1464 (4) ÅT = 100 K
α = 117.805 (6)°0.43 × 0.41 × 0.04 mm
β = 90.939 (4)°
Data collection top
Oxford Diffraction Xcalibur Eos
diffractometer
2186 independent reflections
Absorption correction: analytical
[CrysAlis PRO (Oxford Diffraction, 2009) based on expressions derived by Clark & Reid (1995)]
2078 reflections with I > 2σ(I)
Tmin = 0.083, Tmax = 0.698Rint = 0.021
5668 measured reflectionsθmax = 26.3°
Refinement top
R[F2 > 2σ(F2)] = 0.018H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.041Δρmax = 0.99 e Å3
S = 1.01Δρmin = 0.59 e Å3
2186 reflectionsAbsolute structure: ?
117 parametersAbsolute structure parameter: ?
2 restraintsRogers parameter: ?
Special details top

Experimental. Analytical numeric absorption correction using a multifaceted crystal model based on expressions derived by Clark & Reid (1995).

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
I10.09076 (3)0.38499 (3)0.61148 (3)0.01704 (8)
I20.19010 (3)0.35305 (3)0.90314 (3)0.01422 (7)
I30.26150 (3)0.30976 (3)1.18942 (3)0.01955 (8)
N10.2469 (4)0.8865 (5)0.8153 (4)0.0250 (7)
H110.162 (4)0.782 (3)0.774 (5)0.031 (12)*
H120.236 (6)0.968 (5)0.907 (3)0.037 (13)*
N20.4056 (4)0.7899 (4)0.6047 (4)0.0182 (6)
H20.325 (6)0.686 (6)0.561 (5)0.026 (12)*
C10.3907 (4)0.9236 (5)0.7495 (4)0.0166 (7)
C30.5493 (5)0.8151 (5)0.5310 (5)0.0186 (7)
H30.547 (5)0.712 (6)0.435 (5)0.022*
C40.6862 (5)0.9812 (5)0.5996 (5)0.0217 (8)
H40.783 (6)0.990 (6)0.549 (5)0.026*
C50.6744 (5)1.1248 (5)0.7472 (5)0.0218 (8)
H50.763 (6)1.249 (6)0.799 (5)0.026 (11)*
C60.5316 (5)1.0977 (5)0.8221 (5)0.0192 (7)
H60.520 (5)1.191 (6)0.915 (5)0.023*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
I10.01701 (12)0.01880 (13)0.01929 (13)0.00609 (9)0.00315 (8)0.01316 (10)
I20.01360 (12)0.01388 (12)0.01490 (12)0.00556 (9)0.00260 (8)0.00688 (9)
I30.02394 (13)0.02233 (13)0.01393 (12)0.01008 (10)0.00330 (9)0.00953 (10)
N10.0238 (17)0.0189 (17)0.0238 (17)0.0040 (14)0.0102 (14)0.0070 (15)
N20.0174 (14)0.0122 (15)0.0205 (15)0.0032 (12)0.0019 (12)0.0068 (13)
C10.0165 (16)0.0179 (18)0.0177 (17)0.0060 (14)0.0010 (13)0.0111 (15)
C30.0182 (17)0.0172 (18)0.0216 (18)0.0094 (14)0.0050 (14)0.0090 (15)
C40.0165 (17)0.0216 (19)0.028 (2)0.0087 (15)0.0073 (15)0.0126 (17)
C50.0162 (17)0.0159 (18)0.028 (2)0.0045 (15)0.0002 (14)0.0084 (16)
C60.0181 (17)0.0158 (18)0.0185 (18)0.0063 (14)0.0013 (14)0.0051 (15)
Geometric parameters (Å, º) top
I1—I22.9389 (3)C1—C61.411 (5)
I2—I32.8966 (3)C3—C41.355 (5)
N1—C11.328 (5)C3—H30.93 (4)
N1—H110.849 (10)C4—C51.400 (5)
N1—H120.847 (10)C4—H40.91 (4)
N2—C11.353 (5)C5—C61.358 (5)
N2—C31.354 (5)C5—H50.97 (4)
N2—H20.83 (4)C6—H60.91 (4)
I3—I2—I1176.017 (9)N2—C3—H3115 (3)
C1—N1—H11125 (3)C4—C3—H3124 (3)
C1—N1—H12121 (3)C3—C4—C5118.3 (3)
H11—N1—H12114 (4)C3—C4—H4117 (3)
C1—N2—C3123.2 (3)C5—C4—H4124 (3)
C1—N2—H2118 (3)C6—C5—C4120.9 (3)
C3—N2—H2118 (3)C6—C5—H5116 (2)
N1—C1—N2119.4 (3)C4—C5—H5123 (3)
N1—C1—C6123.5 (3)C5—C6—C1120.0 (3)
N2—C1—C6117.1 (3)C5—C6—H6121 (3)
N2—C3—C4120.4 (3)C1—C6—H6118 (3)
C3—N2—C1—N1178.6 (3)C3—C4—C5—C61.5 (6)
C3—N2—C1—C61.7 (5)C4—C5—C6—C11.2 (6)
C1—N2—C3—C41.4 (5)N1—C1—C6—C5179.9 (4)
N2—C3—C4—C50.3 (6)N2—C1—C6—C50.4 (5)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H11···I10.85 (1)2.99 (3)3.698 (3)142 (4)
N1—H12···I3i0.85 (1)2.89 (2)3.709 (3)164 (4)
N2—H2···I10.83 (4)2.97 (5)3.702 (3)147 (4)
Symmetry code: (i) x, y+1, z.

Experimental details

Crystal data
Chemical formulaC5H7N2+·I3
Mr475.83
Crystal system, space groupTriclinic, P1
Temperature (K)100
a, b, c (Å)8.0446 (4), 8.9973 (5), 9.1464 (4)
α, β, γ (°)117.805 (6), 90.939 (4), 109.640 (5)
V3)539.46 (6)
Z2
Radiation typeMo Kα
µ (mm1)8.64
Crystal size (mm)0.43 × 0.41 × 0.04
Data collection
DiffractometerOxford Diffraction Xcalibur Eos
diffractometer
Absorption correctionAnalytical
[CrysAlis PRO (Oxford Diffraction, 2009) based on expressions derived by Clark & Reid (1995)]
Tmin, Tmax0.083, 0.698
No. of measured, independent and
observed [I > 2σ(I)] reflections
5668, 2186, 2078
Rint0.021
(sin θ/λ)max1)0.623
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.018, 0.041, 1.01
No. of reflections2186
No. of parameters117
No. of restraints2
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.99, 0.59

Computer programs: CrysAlis PRO (Oxford Diffraction, 2009), SHELXS2013 (Sheldrick, 2008), SHELXL2013 (Sheldrick, 2008), DIAMOND (Brandenburg, 2012), publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H11···I10.849 (10)2.99 (3)3.698 (3)142 (4)
N1—H12···I3i0.847 (10)2.887 (17)3.709 (3)164 (4)
N2—H2···I10.83 (4)2.97 (5)3.702 (3)147 (4)
Symmetry code: (i) x, y+1, z.
Acknowledgements top

We thank E. Hammes and P. Roloff for technical support and V. Breuers for useful discussions. This publication was funded by the German Research Foundation (DFG) and the Heinrich-Heine-Universität Düsseldorf under the funding programme Open Access Publishing.

references
References top

Berl, V., Huc, I., Khoury, R. G., Krische, M. J. & Lehn, J.-M. (2000). Nature, 407, 720–723.

Bolliger, J. L., Oberholzer, M. & Frech, C. M. (2011). Adv. Synth. Catal. 353, 945–954.

Brandenburg, K. (2012). DIAMOND. Crystal Impact GbR, Bonn, Germany.

Brown, I. D. (2009). Chem. Rev. 109, 6858–6919.

Chai, S., Zhao, G.-J., Song, P., Yang, S.-Q., Liu, J.-Y. & Han, K.-L. (2009). Phys. Chem. Chem. Phys. 11, 4385–4390.

Chapkanov, A. G. (2010). Struct. Chem. 21, 29–35.

Çırak, Ç., Demir, S., Ucun, F. & Çubuk, O. (2011). Spectrochim. Acta Part A, 79, 529–532.

Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887–897.

Deplano, P., Ferraro, J. R., Mercuri, M. L. & Trogu, E. F. (1999). Coord. Chem. Rev. 188, 71–95.

Egli, R. A. (1969). Z. Anal. Chem. 247, 39–41.

Janiak, C. (2000). Dalton Trans. pp. 3885–3896.

Megen, M. van & Reiss, G. J. (2012). Acta Cryst. E68, o1331–o1332.

Meyer, M. K., Graf, J. & Reiss, G. J. (2010). Z. Naturforsch. Teil B, 65, 1462–1466.

Muñoz-Caro, C. & Niño, A. (2002). Biophys. Chem. 96, 1–14.

Ninković, D. B., Janjić, G. V. & Zarić, S. D. (2012). Cryst. Growth Des. 12, 1060–1063.

Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, England.

Periyasamy, B. K., Jebas, R. S., Gopalakrishnan, N. & Balasubramanian, T. (2007). Mater. Lett. 61, 4246–4249.

Reiss, G. J. & Engel, J. S. (2002). CrystEngComm, 4, 155–161.

Reiss, G. J. & Engel, J. S. (2004). Z. Naturforsch. Teil B, 59, 1114–1117.

Reiss, G. J. & van Megen, M. (2012a). Z. Naturforsch. Teil B, 67, 5–10.

Reiss, G. J. & van Megen, M. (2012b). Z. Naturforsch. Teil B, 67, 447–451.

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

Shkir, M., Riscob, B. & Bhagavannarayana, G. (2012). Solid State Sci. 14, 773–776.

Srinivasan, B. R. & Priolkar, K. R. (2013). Solid State Sci. 20, 15–16.

Testa, A. C. & Wild, U. P. (1981). J. Phys. Chem. 85, 2637–2639.

Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.