4-Cyano­pyridinium bromide

In the title compound, C₆H₅N₂⁺·Br⁻, the pyridine N atom is protonated and involved in an inter­molecular N—H⋯Br hydrogen bond which, together with weak C—H⋯N hydrogen bonds, results in the formation of a chain along the c axis. Weak inter­molecular C—H⋯Br inter­actions between pyridine H atoms and Br⁻ anions connect these chains into a network parallel to the bc plane.

Related literature

For the structures and properties of related compounds see: Fu et al. (2011a,b); Dai & Chen (2011).

Experimental

Crystal data

• C₆H₅N₂⁺·Br⁻

• M_r = 185.03

• Monoclinic, P 2₁ /n

• a = 7.3918 (5) Å

• b = 12.2587 (4) Å

• c = 8.1671 (3) Å

• β = 111.720 (1)°

• V = 687.51 (6) ų

• Z = 4

• Mo Kα radiation

• μ = 5.88 mm⁻¹

• T = 173 K

• 0.10 × 0.05 × 0.05 mm

Data collection

• Rigaku Mercury2 diffractometer

• Absorption correction: multi-scan (CrystalClear; Rigaku, 2005) T_min = 0.910, T_max = 1.000

• 4771 measured reflections

• 1579 independent reflections

• 1296 reflections with I > 2σ(I)

• R_int = 0.047

Refinement

• R[F² > 2σ(F²)] = 0.032

• wR(F²) = 0.066

• S = 0.95

• 1579 reflections

• 82 parameters

• H-atom parameters constrained

• Δρ_max = 0.57 e Å⁻³

• Δρ_min = −0.92 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯Br1^i	0.90	2.26	3.133 (2)	164
C1—H1A⋯Br1	0.93	2.88	3.615 (2)	137
C2—H2A⋯Br1^ii	0.93	2.77	3.645 (2)	156
C5—H5A⋯N2^iii	0.93	2.66	3.435 (4)	142
Symmetry codes: (i) -x+1, -y+1, -z; (ii) -x+1, -y+1, -z+1; (iii) x, y, z-1.

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; 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.

Supporting information

S1. Comment

Simple organic salts containing strong intermolecular H-bonds have attracted attention as materials which display ferroelectric-paraelectric phase transitions (Fu et al., 2011a; Fu et al., 2011b). With the purpose of obtaining crystals of organic salts which might undergo such phase transitions, various organic molecules have been studied and a series of new materials have been elaborated (Dai & Chen 2011). Herewith we present the synthesis and crystal structure of the title compound, 4-cyanopyridinium bromide.

In the title compound (Fig. 1), the bond lengths and angles have normal values. The asymmetric unit is composed of one 4-cyanopyridinium cation and one Br^- anion. The protonated N atom is involved in a strong N—H···Br hydrogen bond (Table 1) which accompanying the C5—H5A···N2 H-bond generates a linear chain parallel to c-axis while weak C1—H1A···Br and C2—H2A···Br1 interactions serve to link the chains into a 3-dimensional layer structure (Fig. 2 and Table 1).

Related literature

For the structures and properties of related compounds see: Fu et al. (2011a,b); Dai & Chen (2011).

S2. Experimental

Isonicotinonitrile (20 mmol), aqueous HBr (5 mL, 2 mol/L) and ethanol (50 mL) were added to a 100mL flask. The mixture was stirred at 60° C for 2 h, and then the precipitate was filtrated out. Colourless crystals suitable for X-ray diffraction were obtained by slow evaporation of the filtrate.

S3. Refinement

All H atoms attached to C atoms were situated into the idealized positions and treated as riding with C–H = 0.93 Å (aromatic) with U_iso(H)=1.2U_eq(C). The positional parameters of the H atom (N) were refined freely. And in the last stage of the refinement, they were restrained with the H—N = 0.90 (2)Å, with U_iso(H)=1.2U_eq(N).

Computing details

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); 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

	Fig. 1. A view of the asymmetric unit with the atomic numbering scheme. The displacement ellipsoids were drawn at the 30% probability level.
	Fig. 2. The crystal packing of the title compound viewed along the a axis showing the N—H···Br, C—H···N and C—H···Br interactions (dotted line) in the title compound.

4-Cyanopyridinium bromide

Crystal data

C6H5N2^+·Br^−	F(000) = 360
Mr = 185.03	Dx = 1.788 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1579 reflections
a = 7.3918 (5) Å	θ = 3.2–27.5°
b = 12.2587 (4) Å	µ = 5.88 mm^−1
c = 8.1671 (3) Å	T = 173 K
β = 111.720 (1)°	Block, colorless
V = 687.51 (6) Å^3	0.10 × 0.05 × 0.05 mm
Z = 4

Data collection

Rigaku Mercury2 diffractometer	1579 independent reflections
Radiation source: fine-focus sealed tube	1296 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.047
Detector resolution: 13.6612 pixels mm^-1	θmax = 27.5°, θmin = 3.2°
ω & ϕ scans	h = −9→9
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −15→15
Tmin = 0.910, Tmax = 1.000	l = −10→10
4771 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.032	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.066	H-atom parameters constrained
S = 0.95	w = 1/[σ^2(Fo^2) + (0.0255P)^2] where P = (Fo^2 + 2Fc^2)/3
1579 reflections	(Δ/σ)max = 0.001
82 parameters	Δρmax = 0.57 e Å^−3
0 restraints	Δρmin = −0.92 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.61085 (4)	0.41149 (2)	0.32517 (4)	0.01972 (12)
N1	0.4087 (4)	0.74050 (19)	−0.0107 (3)	0.0178 (6)
H1	0.4160	0.7079	−0.1068	0.021*
C1	0.4249 (4)	0.6702 (3)	0.1191 (4)	0.0218 (7)
H1A	0.4410	0.5962	0.1038	0.026*
C2	0.4176 (5)	0.7076 (2)	0.2761 (4)	0.0206 (7)
H2A	0.4295	0.6597	0.3677	0.025*
N2	0.3889 (4)	0.8933 (2)	0.5892 (4)	0.0318 (7)
C3	0.3922 (4)	0.8184 (2)	0.2937 (4)	0.0164 (7)
C4	0.3754 (4)	0.8896 (2)	0.1569 (4)	0.0198 (7)
H4A	0.3575	0.9640	0.1682	0.024*
C5	0.3857 (4)	0.8479 (2)	0.0032 (4)	0.0193 (7)
H5A	0.3767	0.8941	−0.0898	0.023*
C6	0.3875 (5)	0.8612 (3)	0.4580 (4)	0.0202 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0246 (2)	0.01924 (19)	0.01933 (18)	−0.00107 (15)	0.01284 (14)	−0.00215 (13)
N1	0.0149 (14)	0.0239 (14)	0.0174 (12)	0.0034 (11)	0.0094 (11)	−0.0039 (11)
C1	0.024 (2)	0.0189 (17)	0.0243 (17)	0.0035 (14)	0.0111 (15)	−0.0006 (14)
C2	0.0201 (18)	0.0237 (17)	0.0206 (16)	0.0045 (14)	0.0106 (14)	0.0037 (14)
N2	0.045 (2)	0.0311 (17)	0.0251 (15)	−0.0001 (15)	0.0200 (14)	−0.0045 (13)
C3	0.0082 (16)	0.0260 (17)	0.0163 (15)	0.0014 (13)	0.0060 (13)	0.0006 (13)
C4	0.0194 (18)	0.0212 (17)	0.0221 (16)	0.0005 (14)	0.0118 (14)	−0.0032 (13)
C5	0.0166 (18)	0.0226 (17)	0.0207 (16)	0.0007 (14)	0.0094 (14)	0.0034 (14)
C6	0.0184 (18)	0.0248 (17)	0.0194 (16)	−0.0007 (14)	0.0093 (14)	0.0022 (14)

Geometric parameters (Å, º)

N1—C1	1.337 (4)	N2—C6	1.138 (4)
N1—C5	1.337 (4)	C3—C4	1.387 (4)
N1—H1	0.9003	C3—C6	1.453 (4)
C1—C2	1.381 (4)	C4—C5	1.384 (4)
C1—H1A	0.9300	C4—H4A	0.9300
C2—C3	1.385 (4)	C5—H5A	0.9300
C2—H2A	0.9300
C1—N1—C5	122.9 (2)	C2—C3—C6	120.0 (3)
C1—N1—H1	112.9	C4—C3—C6	119.4 (3)
C5—N1—H1	124.2	C5—C4—C3	118.6 (3)
N1—C1—C2	120.0 (3)	C5—C4—H4A	120.7
N1—C1—H1A	120.0	C3—C4—H4A	120.7
C2—C1—H1A	120.0	N1—C5—C4	119.5 (3)
C1—C2—C3	118.4 (3)	N1—C5—H5A	120.2
C1—C2—H2A	120.8	C4—C5—H5A	120.2
C3—C2—H2A	120.8	N2—C6—C3	178.0 (4)
C2—C3—C4	120.6 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···Br1^i	0.90	2.26	3.133 (2)	164
C1—H1A···Br1	0.93	2.88	3.615 (2)	137
C2—H2A···Br1^ii	0.93	2.77	3.645 (2)	156
C5—H5A···N2^iii	0.93	2.66	3.435 (4)	142

Symmetry codes: (i) −x+1, −y+1, −z; (ii) −x+1, −y+1, −z+1; (iii) x, y, z−1.