2-Amino-pyridin-1-ium triiodide.

The asymmetric unit of the title compound, C5H7N2 (+.)I3 (-), consists of one 2-amino-pyridin-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-amino-pyridines. 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.

Related literature

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 ▶); Egli (1969 ▶).

Experimental

Crystal data

C5H7N2 +·I3 −

M = 475.83

Triclinic,

a = 8.0446 (4) Å

b = 8.9973 (5) Å

c = 9.1464 (4) Å

α = 117.805 (6)°

β = 90.939 (4)°

γ = 109.640 (5)°

V = 539.46 (6) Å3

Z = 2

Mo Kα radiation

μ = 8.64 mm−1

T = 100 K

0.43 × 0.41 × 0.04 mm

Data collection

Oxford Diffraction Xcalibur Eos diffractometer

Absorption correction: analytical [CrysAlis PRO (Oxford Diffraction, 2009 ▶) based on expressions derived by Clark & Reid (1995 ▶)] T min = 0.083, T max = 0.698

5668 measured reflections

2186 independent reflections

2078 reflections with I > 2σ(I)

R int = 0.021

Refinement

R[F 2 > 2σ(F 2)] = 0.018

wR(F 2) = 0.041

S = 1.01

2186 reflections

117 parameters

2 restraints

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.99 e Å−3

Δρmin = −0.59 e Å−3

Data collection: CrysAlis PRO (Oxford Diffraction, 2009 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; 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 ▶).

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S1600536813015389/hg5319sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813015389/hg5319Isup2.hkl

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

C5H7N2+·I3−	Z = 2
Mr = 475.83	F(000) = 420
Triclinic, P1	Dx = 2.929 Mg m−3
a = 8.0446 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.9973 (5) Å	Cell parameters from 6254 reflections
c = 9.1464 (4) Å	θ = 3.1–32.6°
α = 117.805 (6)°	µ = 8.64 mm−1
β = 90.939 (4)°	T = 100 K
γ = 109.640 (5)°	Plate, orange
V = 539.46 (6) Å3	0.43 × 0.41 × 0.04 mm

Oxford Diffraction Xcalibur Eos diffractometer	2186 independent reflections
Radiation source: Sealed tube X-ray Source	2078 reflections with I > 2σ(I)
Equatorial mounted graphite monochromator	Rint = 0.021
Detector resolution: 16.2711 pixels mm-1	θmax = 26.3°, θmin = 3.1°
ω scans	h = −10→9
Absorption correction: analytical [CrysAlis PRO (Oxford Diffraction, 2009) based on expressions derived by Clark & Reid (1995)]	k = −11→11
Tmin = 0.083, Tmax = 0.698	l = −11→11
5668 measured reflections

Refinement on F2	Hydrogen site location: difference Fourier map
Least-squares matrix: full	H 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 = 1.01	Δρmax = 0.99 e Å−3
2186 reflections	Δρmin = −0.59 e Å−3
117 parameters	Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
2 restraints	Extinction coefficient: 0.0075 (2)

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.

	x	y	z	Uiso*/Ueq
I1	0.09076 (3)	0.38499 (3)	0.61148 (3)	0.01704 (8)
I2	0.19010 (3)	0.35305 (3)	0.90314 (3)	0.01422 (7)
I3	0.26150 (3)	0.30976 (3)	1.18942 (3)	0.01955 (8)
N1	0.2469 (4)	0.8865 (5)	0.8153 (4)	0.0250 (7)
H11	0.162 (4)	0.782 (3)	0.774 (5)	0.031 (12)*
H12	0.236 (6)	0.968 (5)	0.907 (3)	0.037 (13)*
N2	0.4056 (4)	0.7899 (4)	0.6047 (4)	0.0182 (6)
H2	0.325 (6)	0.686 (6)	0.561 (5)	0.026 (12)*
C1	0.3907 (4)	0.9236 (5)	0.7495 (4)	0.0166 (7)
C3	0.5493 (5)	0.8151 (5)	0.5310 (5)	0.0186 (7)
H3	0.547 (5)	0.712 (6)	0.435 (5)	0.022*
C4	0.6862 (5)	0.9812 (5)	0.5996 (5)	0.0217 (8)
H4	0.783 (6)	0.990 (6)	0.549 (5)	0.026*
C5	0.6744 (5)	1.1248 (5)	0.7472 (5)	0.0218 (8)
H5	0.763 (6)	1.249 (6)	0.799 (5)	0.026 (11)*
C6	0.5316 (5)	1.0977 (5)	0.8221 (5)	0.0192 (7)
H6	0.520 (5)	1.191 (6)	0.915 (5)	0.023*

	U11	U22	U33	U12	U13	U23
I1	0.01701 (12)	0.01880 (13)	0.01929 (13)	0.00609 (9)	0.00315 (8)	0.01316 (10)
I2	0.01360 (12)	0.01388 (12)	0.01490 (12)	0.00556 (9)	0.00260 (8)	0.00688 (9)
I3	0.02394 (13)	0.02233 (13)	0.01393 (12)	0.01008 (10)	0.00330 (9)	0.00953 (10)
N1	0.0238 (17)	0.0189 (17)	0.0238 (17)	0.0040 (14)	0.0102 (14)	0.0070 (15)
N2	0.0174 (14)	0.0122 (15)	0.0205 (15)	0.0032 (12)	0.0019 (12)	0.0068 (13)
C1	0.0165 (16)	0.0179 (18)	0.0177 (17)	0.0060 (14)	0.0010 (13)	0.0111 (15)
C3	0.0182 (17)	0.0172 (18)	0.0216 (18)	0.0094 (14)	0.0050 (14)	0.0090 (15)
C4	0.0165 (17)	0.0216 (19)	0.028 (2)	0.0087 (15)	0.0073 (15)	0.0126 (17)
C5	0.0162 (17)	0.0159 (18)	0.028 (2)	0.0045 (15)	0.0002 (14)	0.0084 (16)
C6	0.0181 (17)	0.0158 (18)	0.0185 (18)	0.0063 (14)	−0.0013 (14)	0.0051 (15)

I1—I2	2.9389 (3)	C1—C6	1.411 (5)
I2—I3	2.8966 (3)	C3—C4	1.355 (5)
N1—C1	1.328 (5)	C3—H3	0.93 (4)
N1—H11	0.849 (10)	C4—C5	1.400 (5)
N1—H12	0.847 (10)	C4—H4	0.91 (4)
N2—C1	1.353 (5)	C5—C6	1.358 (5)
N2—C3	1.354 (5)	C5—H5	0.97 (4)
N2—H2	0.83 (4)	C6—H6	0.91 (4)
I3—I2—I1	176.017 (9)	N2—C3—H3	115 (3)
C1—N1—H11	125 (3)	C4—C3—H3	124 (3)
C1—N1—H12	121 (3)	C3—C4—C5	118.3 (3)
H11—N1—H12	114 (4)	C3—C4—H4	117 (3)
C1—N2—C3	123.2 (3)	C5—C4—H4	124 (3)
C1—N2—H2	118 (3)	C6—C5—C4	120.9 (3)
C3—N2—H2	118 (3)	C6—C5—H5	116 (2)
N1—C1—N2	119.4 (3)	C4—C5—H5	123 (3)
N1—C1—C6	123.5 (3)	C5—C6—C1	120.0 (3)
N2—C1—C6	117.1 (3)	C5—C6—H6	121 (3)
N2—C3—C4	120.4 (3)	C1—C6—H6	118 (3)
C3—N2—C1—N1	−178.6 (3)	C3—C4—C5—C6	1.5 (6)
C3—N2—C1—C6	1.7 (5)	C4—C5—C6—C1	−1.2 (6)
C1—N2—C3—C4	−1.4 (5)	N1—C1—C6—C5	179.9 (4)
N2—C3—C4—C5	−0.3 (6)	N2—C1—C6—C5	−0.4 (5)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H11···I1	0.85 (1)	2.99 (3)	3.698 (3)	142 (4)
N1—H12···I3i	0.85 (1)	2.89 (2)	3.709 (3)	164 (4)
N2—H2···I1	0.83 (4)	2.97 (5)	3.702 (3)	147 (4)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H11⋯I1	0.85 (1)	2.99 (3)	3.698 (3)	142 (4)
N1—H12⋯I3i	0.85 (1)	2.89 (2)	3.709 (3)	164 (4)
N2—H2⋯I1	0.83 (4)	2.97 (5)	3.702 (3)	147 (4)

Symmetry code: (i) .