3-Cyano-N-methyl­pyridinium bromide

The title compound, C₇H₇N₂⁺·Br⁻, forms a layered solid with each cation forming three strong and one weaker C—H...Br hydrogen bonds within the layer. All atoms except two of the methyl H atoms lie on a mirror plane.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.029
• wR factor = 0.063
• Data-to-parameter ratio = 101.2

checkCIF/PLATON results

No syntax errors found



Alert level A
REFLT03_ALERT_3_A  Reflection count > 15% excess reflns - sys abs data present?
           From the CIF: _diffrn_reflns_theta_max           27.74
           From the CIF: _diffrn_reflns_theta_full           0.00
           From the CIF: _reflns_number_total               6277
           TEST2: Reflns within _diffrn_reflns_theta_max
           Count of symmetry unique reflns         1054
           Completeness (_total/calc)            595.54%

Author Response: ...Crystal was twinned so final refinement was performed with a SHELX HKLF5-type multicomponent file. Such a refinement with SHELXL requires that no merging of equivalent reflections be performed. This is to avoid averaging symmetry equivalent reflections with differing contributions from the two twin components. This is the reason for the "excess reflections". This is addressed in the _publ_section_exptl_refinement section.

PLAT021_ALERT_1_A Ratio Unique / Expected Reflections too High ...       5.95

Author Response: ...Same as previous response.

Alert level B
PLAT230_ALERT_2_B Hirshfeld Test Diff for    C3     -   C7      ..       8.09 su

Alert level C
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.96
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C3     -   C7     ...       1.44 Ang.

   2 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT-Plus (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: SHELXTL.

3-cyano-N-methylpyridinium bromide

Crystal data

C7H7N2^+·Br^−	F(000) = 196
Mr = 199.06	Dx = 1.600 Mg m^−3
Monoclinic, P21/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yb	Cell parameters from 4284 reflections
a = 8.109 (1) Å	θ = 2.7–28.2°
b = 6.6266 (8) Å	µ = 4.90 mm^−1
c = 8.381 (1) Å	T = 100 K
β = 113.406 (2)°	Plate, colorless
V = 413.30 (9) Å^3	0.16 × 0.11 × 0.01 mm
Z = 2

Data collection

Bruker SMART APEX CCD area-detector diffractometer	6277 independent reflections
Radiation source: fine-focus sealed tube	5502 reflections with I > 2σ(I)
Graphite monochromator	θmax = 27.7°, θmin = 2.7°
φ and ω scans	h = −10→10
Absorption correction: multi-scan (TWINABS; Sheldrick, 2003)	k = −8→8
Tmin = 0.515, Tmax = 0.948	l = −10→10
6277 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)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.063	H-atom parameters constrained
S = 0.93	w = 1/[σ^2(Fo^2) + (0.0295P)^2] where P = (Fo^2 + 2Fc^2)/3
6277 reflections	(Δ/σ)max = 0.002
62 parameters	Δρmax = 1.15 e Å^−3
0 restraints	Δρmin = −0.39 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Br	0.16283 (3)	0.2500	0.39522 (2)	0.02087 (6)
N1	0.72977 (19)	0.2500	0.57911 (18)	0.0178 (3)
N2	1.3436 (2)	0.2500	0.9680 (2)	0.0384 (4)
C1	0.6408 (2)	0.2500	0.3861 (2)	0.0271 (5)
H1A	0.5165	0.2500	0.3640	0.041*
H1B	0.6813	0.1344	0.3550	0.041*
C2	0.9091 (2)	0.2500	0.6533 (2)	0.0201 (4)
H2	0.9767	0.2500	0.5831	0.024*
C3	0.9959 (2)	0.2500	0.8321 (2)	0.0199 (4)
C4	0.8981 (2)	0.2500	0.9360 (2)	0.0233 (4)
H4	0.9568	0.2500	1.0593	0.028*
C5	0.7118 (2)	0.2500	0.8537 (2)	0.0262 (4)
H5	0.6408	0.2500	0.9206	0.031*
C6	0.6307 (2)	0.2500	0.6754 (2)	0.0230 (4)
H6	0.5032	0.2500	0.6194	0.028*
C7	1.1898 (3)	0.2500	0.9081 (2)	0.0245 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br	0.02230 (10)	0.01909 (9)	0.01987 (10)	0.000	0.00694 (8)	0.000
N1	0.0194 (8)	0.0151 (7)	0.0162 (8)	0.000	0.0042 (7)	0.000
N2	0.0243 (10)	0.0581 (12)	0.0323 (10)	0.000	0.0108 (8)	0.000
C1	0.0287 (12)	0.0273 (10)	0.0215 (10)	0.000	0.0059 (9)	0.000
C2	0.0219 (9)	0.0162 (9)	0.0268 (11)	0.000	0.0146 (8)	0.000
C3	0.0171 (10)	0.0167 (8)	0.0226 (10)	0.000	0.0044 (8)	0.000
C4	0.0254 (10)	0.0228 (9)	0.0186 (10)	0.000	0.0055 (8)	0.000
C5	0.0246 (10)	0.0291 (10)	0.0273 (12)	0.000	0.0128 (9)	0.000
C6	0.0159 (9)	0.0232 (9)	0.0257 (11)	0.000	0.0037 (8)	0.000
C7	0.0284 (12)	0.0227 (9)	0.0228 (10)	0.000	0.0105 (9)	0.000

Geometric parameters (Å, º)

N1—C2	1.335 (2)	C3—C4	1.392 (2)
N1—C6	1.346 (2)	C3—C7	1.442 (2)
N1—C1	1.487 (2)	C4—C5	1.389 (2)
N2—C7	1.145 (2)	C4—H4	0.95
C1—H1A	0.95	C5—C6	1.373 (2)
C1—H1B	0.91	C5—H5	0.95
C2—C3	1.380 (2)	C6—H6	0.95
C2—H2	0.95
C2—N1—C6	121.34 (15)	C4—C3—C7	121.05 (17)
C2—N1—C1	118.32 (16)	C5—C4—C3	117.84 (18)
C6—N1—C1	120.34 (14)	C5—C4—H4	121.1
N1—C1—H1A	103.3	C3—C4—H4	121.1
N1—C1—H1B	103.7	C6—C5—C4	119.80 (18)
H1A—C1—H1B	114.8	C6—C5—H5	120.1
N1—C2—C3	119.80 (17)	C4—C5—H5	120.1
N1—C2—H2	120.1	N1—C6—C5	120.68 (16)
C3—C2—H2	120.1	N1—C6—H6	119.7
C2—C3—C4	120.53 (17)	C5—C6—H6	119.7
C2—C3—C7	118.42 (17)	N2—C7—C3	179.8 (2)