2-Amino-5-methyl­pyridinium 3-chloro­benzoate

The 3-chloro­benzoate anion of the title salt, C₆H₉N₂⁺·C₇H₄ClO₂⁻, is nearly planar with a dihedral angle of 2.44 (13)° between the benzene ring and the carboxyl­ate group. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl­ate O atoms of the anion via a pair of N—H...O hydrogen bonds with an R₂²(8) ring motif, forming an approximately planar ion pair with a dihedral angle of 7.92 (5)° between the pyridinium and benzene rings. The ion pairs are further connected via N—H...O and C—H...O hydrogen bonds, forming a two-dimensional network parallel to the bc plane.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.038
• wR factor = 0.115
• Data-to-parameter ratio = 20.6

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT431_ALERT_2_C Short Inter HL..A  Contact  Cl1    ..  O2      .       3.11 Ang.
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         15
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          2

Alert level G
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT042_ALERT_1_G Calc. and Reported MoietyFormula Strings  Differ          ?
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........          3
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600         30

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   3 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   4 ALERT level G = General information/check it is not something unexpected

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Pyridine and its derivatives play an important role in heterocyclic chemistry (Pozharski et al., 1997; Katritzky et al., 1996). They are often involved in hydrogen-bond interactions (Jeffrey, 1997; Scheiner, 1997). In order to study some interesting hydrogen bonding interactions, the synthesis and structure of the title compound, (I), is presented here.

The asymmetric unit of the title compound contains a protonated 2-amino-5-methylpyridinium cation and a 3-chlorobenzoate anion (Fig. 1). In the 2-amino-5-methylpyridinium cation, a wider than normal angle [C1—N1—C5 = 122.50 (10)°] is subtended at the protonated N1 atom. The 2-amino-5-methylpyridinium cation is planar with a maximum deviation of 0.001 (1) Å for atom C2. The dihedral angle between the pyridine (N1/C1–C5) and benzene (C8–C13) rings is 7.92 (5)°. The bond lengths (Allen et al., 1987) and angles are normal. In the crystal packing (Fig. 2), the protonated N1 atom and a nitrogen atom of the 2-amino group (N2) are hydrogen-bonded to the carboxylate oxygen atoms (O1 and O2) via a pair of N—H···O hydrogen bonds (Table 1), forming a ring motif R₂²(8) (Bernstein et al., 1995). Furthermore, these motifs are connected via N2—H2N2···O1ⁱ and C2—H2A···O2ⁱⁱ hydrogen bonds to form a two-dimensional network parallel to the bc plane.

Related literature

For background to the chemistry of substituted pyridines, see: Pozharski et al. (1997); Katritzky et al. (1996). For details of hydrogen bonding, see: Jeffrey (1997); Scheiner (1997). For hydrogen-bond motifs, see: Bernstein et al. (1995). For bond-length data, see: Allen et al. (1987). For stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986).

S2. Experimental

Hot methanol solutions (20 ml) of 2-amino5-methylpyridine (54 mg, Aldrich) and 3-chlorobenzoic acid (39 mg, Merck) were mixed and warmed over a heating magnetic stirrer hotplate for a few minutes. The resulting solution was allowed to cool slowly at room temperature and crystals of the title compound (I) appeared after a few days.

S3. Refinement

N-bound H atoms were located in a difference Fourier maps and refined freely [refined N—H distances 1.00 (2), 0.949 (19) and 0.90 (2) Å]. The remaining H atoms were positioned geometrically (C—H= 0.95 and 0.98 Å) and were refined using a riding model, with U_iso(H) = 1.2 U_eq(C) or 1.5U_eq(methyl C). A rotating-group model was used for the methyl group. In the final refinement, four outliers were omitted (1 1 8, 1 0 8, 2 3 1 and -1 4 8).

Computing details

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

	Fig. 1. The molecular structure of the title compound with atom labels with 50% probability displacement ellipsoids.
	Fig. 2. The crystal packing of the title compound, showing hydrogen-bonded (dashed lines) two-dimensional networks parallel to the bc plane.

2-Amino-5-methylpyridinium 3-chlorobenzoate

Crystal data

C6H9N2^+·C7H4ClO2^−	F(000) = 552
Mr = 264.70	Dx = 1.406 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 6768 reflections
a = 9.0318 (11) Å	θ = 2.3–30.1°
b = 11.6590 (14) Å	µ = 0.30 mm^−1
c = 12.1166 (15) Å	T = 100 K
β = 101.521 (2)°	Block, colourless
V = 1250.2 (3) Å^3	0.53 × 0.31 × 0.22 mm
Z = 4

Data collection

Bruker SMART APEXII DUO CCD area-detector diffractometer	3629 independent reflections
Radiation source: fine-focus sealed tube	3201 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
ϕ and ω scans	θmax = 30.1°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −12→12
Tmin = 0.856, Tmax = 0.936	k = −16→16
13594 measured reflections	l = −17→17

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)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.115	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ^2(Fo^2) + (0.070P)^2 + 0.2814P] where P = (Fo^2 + 2Fc^2)/3
3629 reflections	(Δ/σ)max < 0.001
176 parameters	Δρmax = 0.48 e Å^−3
0 restraints	Δρmin = −0.33 e Å^−3

Special details

Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

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
Cl1	1.05016 (3)	0.25195 (2)	0.66489 (3)	0.02535 (11)
O1	0.60056 (10)	0.65207 (8)	0.46906 (7)	0.02385 (19)
O2	0.72588 (10)	0.62484 (8)	0.64581 (7)	0.02350 (19)
N1	0.45310 (10)	0.81988 (8)	0.55172 (8)	0.01776 (19)
N2	0.55220 (12)	0.77783 (10)	0.73908 (9)	0.0219 (2)
C1	0.46396 (12)	0.84318 (9)	0.66248 (10)	0.0179 (2)
C2	0.37858 (13)	0.93693 (10)	0.69173 (10)	0.0210 (2)
H2A	0.3833	0.9561	0.7686	0.025*
C3	0.28968 (13)	0.99913 (10)	0.60827 (11)	0.0218 (2)
H3A	0.2327	1.0615	0.6283	0.026*
C4	0.27996 (12)	0.97334 (10)	0.49275 (10)	0.0204 (2)
C5	0.36421 (12)	0.88246 (10)	0.46891 (10)	0.0190 (2)
H5A	0.3607	0.8624	0.3924	0.023*
C6	0.18156 (14)	1.04262 (11)	0.40224 (11)	0.0262 (3)
H6A	0.1968	1.0170	0.3283	0.039*
H6B	0.2084	1.1239	0.4124	0.039*
H6C	0.0754	1.0321	0.4070	0.039*
C7	0.69320 (12)	0.59788 (9)	0.54401 (9)	0.0175 (2)
C8	0.76799 (11)	0.49160 (9)	0.50805 (9)	0.0159 (2)
C9	0.86515 (12)	0.42923 (9)	0.59063 (9)	0.0172 (2)
H9A	0.8840	0.4537	0.6670	0.021*
C10	0.93380 (12)	0.33117 (9)	0.55982 (10)	0.0180 (2)
C11	0.91118 (13)	0.29472 (10)	0.44867 (10)	0.0212 (2)
H11A	0.9603	0.2280	0.4288	0.025*
C12	0.81496 (13)	0.35797 (10)	0.36693 (10)	0.0224 (2)
H12A	0.7987	0.3345	0.2904	0.027*
C13	0.74215 (12)	0.45553 (10)	0.39638 (9)	0.0198 (2)
H13A	0.6750	0.4973	0.3402	0.024*
H1N1	0.511 (3)	0.7554 (18)	0.526 (2)	0.055 (7)*
H1N2	0.617 (2)	0.7251 (16)	0.7129 (17)	0.037 (5)*
H2N2	0.574 (2)	0.8015 (16)	0.8114 (16)	0.035 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.02441 (17)	0.02607 (17)	0.02424 (17)	0.00991 (9)	0.00168 (12)	0.00262 (10)
O1	0.0302 (4)	0.0259 (4)	0.0161 (4)	0.0125 (3)	0.0061 (3)	0.0030 (3)
O2	0.0285 (4)	0.0253 (4)	0.0163 (4)	0.0075 (3)	0.0034 (3)	−0.0021 (3)
N1	0.0183 (4)	0.0195 (4)	0.0156 (4)	0.0034 (3)	0.0037 (3)	−0.0019 (3)
N2	0.0240 (5)	0.0262 (5)	0.0150 (5)	0.0050 (4)	0.0025 (4)	−0.0025 (4)
C1	0.0168 (5)	0.0201 (5)	0.0173 (5)	−0.0003 (4)	0.0047 (4)	−0.0028 (4)
C2	0.0206 (5)	0.0231 (5)	0.0203 (5)	0.0005 (4)	0.0066 (4)	−0.0061 (4)
C3	0.0193 (5)	0.0207 (5)	0.0263 (6)	0.0030 (4)	0.0064 (4)	−0.0047 (4)
C4	0.0183 (5)	0.0202 (5)	0.0230 (5)	0.0024 (4)	0.0045 (4)	0.0000 (4)
C5	0.0189 (5)	0.0215 (5)	0.0166 (5)	0.0021 (4)	0.0038 (4)	−0.0006 (4)
C6	0.0253 (6)	0.0258 (6)	0.0269 (6)	0.0084 (4)	0.0038 (5)	0.0024 (5)
C7	0.0195 (5)	0.0181 (5)	0.0163 (5)	0.0023 (4)	0.0069 (4)	0.0013 (4)
C8	0.0156 (4)	0.0169 (4)	0.0159 (5)	0.0012 (3)	0.0049 (4)	0.0000 (4)
C9	0.0166 (4)	0.0187 (5)	0.0164 (5)	0.0011 (4)	0.0037 (4)	0.0000 (4)
C10	0.0146 (4)	0.0188 (5)	0.0205 (5)	0.0019 (3)	0.0030 (4)	0.0016 (4)
C11	0.0197 (5)	0.0203 (5)	0.0238 (6)	0.0029 (4)	0.0046 (4)	−0.0039 (4)
C12	0.0242 (5)	0.0246 (5)	0.0182 (5)	0.0032 (4)	0.0036 (4)	−0.0047 (4)
C13	0.0208 (5)	0.0223 (5)	0.0160 (5)	0.0033 (4)	0.0029 (4)	−0.0003 (4)

Geometric parameters (Å, º)

Cl1—C10	1.7447 (11)	C5—H5A	0.9500
O1—C7	1.2729 (13)	C6—H6A	0.9800
O2—C7	1.2498 (14)	C6—H6B	0.9800
N1—C1	1.3535 (14)	C6—H6C	0.9800
N1—C5	1.3645 (14)	C7—C8	1.5163 (15)
N1—H1N1	1.00 (2)	C8—C13	1.3914 (15)
N2—C1	1.3348 (15)	C8—C9	1.3961 (15)
N2—H1N2	0.949 (19)	C9—C10	1.3870 (15)
N2—H2N2	0.90 (2)	C9—H9A	0.9500
C1—C2	1.4227 (15)	C10—C11	1.3878 (16)
C2—C3	1.3671 (17)	C11—C12	1.3914 (16)
C2—H2A	0.9500	C11—H11A	0.9500
C3—C4	1.4171 (17)	C12—C13	1.3955 (16)
C3—H3A	0.9500	C12—H12A	0.9500
C4—C5	1.3686 (15)	C13—H13A	0.9500
C4—C6	1.5019 (16)
C1—N1—C5	122.50 (10)	C4—C6—H6C	109.5
C1—N1—H1N1	121.5 (14)	H6A—C6—H6C	109.5
C5—N1—H1N1	116.0 (14)	H6B—C6—H6C	109.5
C1—N2—H1N2	117.5 (12)	O2—C7—O1	124.84 (10)
C1—N2—H2N2	119.1 (12)	O2—C7—C8	117.27 (9)
H1N2—N2—H2N2	119.4 (17)	O1—C7—C8	117.88 (10)
N2—C1—N1	119.33 (10)	C13—C8—C9	119.93 (10)
N2—C1—C2	122.91 (11)	C13—C8—C7	121.91 (9)
N1—C1—C2	117.75 (10)	C9—C8—C7	118.16 (9)
C3—C2—C1	119.39 (11)	C10—C9—C8	119.15 (10)
C3—C2—H2A	120.3	C10—C9—H9A	120.4
C1—C2—H2A	120.3	C8—C9—H9A	120.4
C2—C3—C4	121.97 (10)	C9—C10—C11	121.77 (10)
C2—C3—H3A	119.0	C9—C10—Cl1	118.45 (9)
C4—C3—H3A	119.0	C11—C10—Cl1	119.77 (8)
C5—C4—C3	116.45 (10)	C10—C11—C12	118.59 (10)
C5—C4—C6	122.35 (11)	C10—C11—H11A	120.7
C3—C4—C6	121.20 (10)	C12—C11—H11A	120.7
N1—C5—C4	121.94 (10)	C11—C12—C13	120.61 (11)
N1—C5—H5A	119.0	C11—C12—H12A	119.7
C4—C5—H5A	119.0	C13—C12—H12A	119.7
C4—C6—H6A	109.5	C8—C13—C12	119.93 (10)
C4—C6—H6B	109.5	C8—C13—H13A	120.0
H6A—C6—H6B	109.5	C12—C13—H13A	120.0
C5—N1—C1—N2	179.47 (10)	O2—C7—C8—C9	1.54 (15)
C5—N1—C1—C2	−0.06 (16)	O1—C7—C8—C9	−177.53 (10)
N2—C1—C2—C3	−179.39 (11)	C13—C8—C9—C10	−0.51 (16)
N1—C1—C2—C3	0.12 (16)	C7—C8—C9—C10	179.45 (9)
C1—C2—C3—C4	−0.16 (18)	C8—C9—C10—C11	1.46 (16)
C2—C3—C4—C5	0.13 (17)	C8—C9—C10—Cl1	−178.02 (8)
C2—C3—C4—C6	179.96 (11)	C9—C10—C11—C12	−1.01 (17)
C1—N1—C5—C4	0.03 (17)	Cl1—C10—C11—C12	178.47 (9)
C3—C4—C5—N1	−0.06 (16)	C10—C11—C12—C13	−0.39 (18)
C6—C4—C5—N1	−179.89 (10)	C9—C8—C13—C12	−0.85 (17)
O2—C7—C8—C13	−178.50 (10)	C7—C8—C13—C12	179.19 (10)
O1—C7—C8—C13	2.43 (16)	C11—C12—C13—C8	1.32 (18)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N1···O1	1.00 (2)	1.68 (2)	2.6716 (13)	174 (2)
N2—H1N2···O2	0.946 (19)	1.820 (19)	2.7618 (15)	173.0 (19)
N2—H2N2···O1^i	0.90 (2)	1.95 (2)	2.8526 (14)	174.0 (17)
C2—H2A···O2^ii	0.95	2.52	3.2104 (15)	130

Symmetry codes: (i) x, −y+3/2, z+1/2; (ii) −x+1, y+1/2, −z+3/2.