2-Amino-4-methyl­pyridinium 3-chloro­benzoate

In the title salt, C₆H₉N₂⁺·C₇H₄ClO₂⁻, the 2-amino-4-methyl­pyridinium cation is almost planar, with a maximum deviation of 0.010 (1) Å. 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, forming an R₂²(8) ring motif. 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 = 0.029
• wR factor = 0.117
• Data-to-parameter ratio = 25.7

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT112_ALERT_2_B ADDSYM Detects Additional (Pseudo) Symm. Elem...          X

Alert level C
SHFSU01_ALERT_2_C  Test not performed. _refine_ls_shift/su_max and
            _refine_ls_shift/esd_max not present.
            Absolute value of the parameter shift to su ratio given   0.001
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          6
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         18
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          6
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          7

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           32.49
           From the CIF: _reflns_number_total               4207
           Count of symmetry unique reflns         2376
           Completeness (_total/calc)            177.06%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured      1831
           Fraction of Friedel pairs measured     0.771
           Are heavy atom types Z>Si present        yes
PLAT916_ALERT_2_G Hooft y and Flack x Parameter values differ by .       0.51
PLAT917_ALERT_2_G The FCF is likely NOT based on a BASF/TWIN Flack          !

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

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

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S1. Comment

Recently, much attention has been devoted to the design and synthesis of supramolecular architectures assembled via various weak noncovalent interactions, such as hydrogen bonds, π···π stacking and C—H···π interactions (Remenar et al., 2003; Aakeroÿ et al., 2001; Sokolov et al., 2006). 2-Aminopyridine and its derivatives are used in the manufacture of pharmaceuticals, hair dyes and other dyes. They are often involved in hydrogen-bond interactions (Jeffrey & Saenger, 1991; Jeffrey, 1997; Scheiner, 1997). The crystal structures of 2-amino-4-methyl pyridine (Kvick & Noordik, 1977) and 2-amino-4-methylpyridinium 4-aminobenzoate (Shen et al., 2008) have been reported. We have recently reported the crystal structures of 2-amino-4-methylpyridinium 4-nitrobenzoate (Hemamalini & Fun, 2010a) and 2-Amino-4-methylpyridinium trifluoroacetate (Hemamalini & Fun, 2010b) from our laboratory. In continuation of our studies of pyridinium derivatives, the crystal structure determination of the title salt has been undertaken.

The asymmetric unit of the title compound, (Fig 1), contains a protonated 2-amino-4-methylpyridinium cation and a 3-chlorobenzoate anion. The 2-amino-4-methylpyridinium cation is planar, with a maximum deviation of 0.010 (1) Å for atom C1. The protonated N1 atom has lead to a slight increase in the C1—N1—C5 angle to 121.66 (11)°, compared to the corresponding angle of 117.3 (1)° in neutral 2-amino-4-methylpyridine (Kvick & Noordik, 1977). The bond lengths (Allen et al., 1987) and angles are normal.

In the crystal packing, (Fig. 2), the protonated N atom and 2-amino group (N2) is hydrogen-bonded to the carboxylate oxygen atoms (O1 and O2) via a pair of N—H···O hydrogen bonds leading to the formation of a R²₂(8) ring (Bernstein et al., 1995). Furthermore, these motifs are connected via N2—H2C···O2 and C5—H5A···O1 hydrogen bonds to form two-dimensional networks parallel to the bc-plane.

Related literature

For details of non-covalent interactions, see: Remenar et al. (2003); Aakeroÿ et al. (2001); Sokolov et al. (2006). For related structures, see: Kvick & Noordik (1977); Shen et al. (2008); Hemamalini & Fun (2010a,b). For details of hydrogen bonding, see: Jeffrey & Saenger (1991); Jeffrey (1997); Scheiner (1997). For hydrogen-bond motifs, see: Bernstein et al. (1995). For bond-length data, see: Allen et al. (1987). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).

S2. Experimental

A hot methanol solution (20 ml) of 2-amino-4-methylpyridine (54 mg, Aldrich) and 3-chlorobenzoic acid (78 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 colourless needles of (I) appeared after a few days.

S3. Refinement

All hydrogen atoms were positioned geometrically [C–H = 0.93 or 0.96 Å] and were refined using a riding model, with U_iso(H) = 1.2 or 1.5 U_eq(C). A rotating group model was used for the methyl group. 1860 Friedel pairs were used to determine the absolute configuration.

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 asymmetric unit of (I). Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. The crystal packing of (I), showing hydrogen-bonded (dashed lines) 2D networks parallel to the bc-plane.

2-Amino-4-methylpyridinium 3-chlorobenzoate

Crystal data

C6H9N2^+·C7H4ClO2^−	F(000) = 276
Mr = 264.70	Dx = 1.432 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 6601 reflections
a = 7.9930 (6) Å	θ = 3.9–35.1°
b = 6.8608 (5) Å	µ = 0.31 mm^−1
c = 11.2148 (9) Å	T = 100 K
β = 93.526 (2)°	Needle, colourless
V = 613.84 (8) Å^3	0.28 × 0.17 × 0.10 mm
Z = 2

Data collection

Bruker APEXII DUO CCD diffractometer	4207 independent reflections
Radiation source: fine-focus sealed tube	4076 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.019
ϕ and ω scans	θmax = 32.5°, θmin = 3.9°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −12→12
Tmin = 0.919, Tmax = 0.971	k = −10→10
9325 measured reflections	l = −16→16

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.029	H-atom parameters constrained
wR(F^2) = 0.117	w = 1/[σ^2(Fo^2) + (0.0801P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.22	(Δ/σ)max < 0.001
4207 reflections	Δρmax = 0.64 e Å^−3
164 parameters	Δρmin = −0.54 e Å^−3
1 restraint	Absolute structure: Flack (1983), 1860 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.01 (4)

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 s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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	0.03584 (4)	1.13218 (6)	0.91629 (3)	0.02460 (10)
O1	0.36548 (12)	0.41445 (16)	0.66474 (7)	0.01744 (18)
O2	0.36855 (12)	0.47553 (16)	0.86099 (7)	0.01876 (19)
C7	0.18473 (15)	0.7570 (2)	0.61091 (10)	0.0158 (2)
H7A	0.2131	0.6782	0.5478	0.019*
C8	0.09543 (15)	0.9288 (2)	0.58796 (11)	0.0197 (2)
H8A	0.0654	0.9648	0.5096	0.024*
C9	0.05103 (16)	1.0466 (2)	0.68188 (12)	0.0195 (2)
H9A	−0.0078	1.1618	0.6671	0.023*
C10	0.09626 (15)	0.9890 (2)	0.79852 (10)	0.0159 (2)
C11	0.18604 (14)	0.8195 (2)	0.82290 (10)	0.0148 (2)
H11A	0.2155	0.7838	0.9014	0.018*
C12	0.23182 (14)	0.70259 (19)	0.72825 (10)	0.01258 (19)
C13	0.32902 (14)	0.51628 (19)	0.75345 (10)	0.0131 (2)
N1	0.53373 (13)	1.07928 (17)	0.70756 (8)	0.01350 (18)
H1A	0.4786	1.1863	0.6979	0.016*
N2	0.53701 (13)	1.1268 (3)	0.91147 (8)	0.0185 (2)
H2B	0.4837	1.2344	0.8986	0.022*
H2C	0.5638	1.0902	0.9835	0.022*
C1	0.57797 (14)	1.01721 (19)	0.82012 (10)	0.0133 (2)
C2	0.66378 (14)	0.8378 (2)	0.83484 (10)	0.0144 (2)
H2A	0.6936	0.7919	0.9112	0.017*
C3	0.70348 (14)	0.73057 (19)	0.73661 (10)	0.0141 (2)
C4	0.65921 (14)	0.8046 (2)	0.62099 (10)	0.0152 (2)
H4A	0.6878	0.7364	0.5535	0.018*
C5	0.57458 (14)	0.9762 (2)	0.60956 (9)	0.0143 (2)
H5A	0.5441	1.0239	0.5337	0.017*
C6	0.79035 (16)	0.5371 (2)	0.75110 (12)	0.0195 (2)
H6A	0.9016	0.5472	0.7239	0.029*
H6B	0.7286	0.4404	0.7048	0.029*
H6C	0.7964	0.5002	0.8338	0.029*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.02597 (15)	0.02386 (18)	0.02371 (15)	0.00755 (12)	−0.00058 (10)	−0.00950 (12)
O1	0.0271 (4)	0.0139 (4)	0.0114 (3)	0.0054 (3)	0.0016 (3)	−0.0014 (3)
O2	0.0299 (4)	0.0157 (5)	0.0104 (3)	0.0044 (4)	−0.0002 (3)	0.0000 (3)
C7	0.0166 (4)	0.0184 (6)	0.0123 (4)	0.0012 (4)	0.0013 (3)	0.0016 (4)
C8	0.0203 (5)	0.0227 (7)	0.0160 (5)	0.0047 (5)	0.0006 (4)	0.0050 (5)
C9	0.0189 (5)	0.0184 (7)	0.0213 (5)	0.0041 (4)	0.0007 (4)	0.0019 (5)
C10	0.0147 (4)	0.0158 (6)	0.0173 (4)	0.0005 (4)	0.0016 (3)	−0.0023 (4)
C11	0.0159 (4)	0.0148 (6)	0.0135 (4)	0.0000 (4)	0.0007 (3)	−0.0009 (4)
C12	0.0131 (4)	0.0126 (5)	0.0121 (4)	−0.0009 (4)	0.0013 (3)	0.0007 (4)
C13	0.0175 (4)	0.0108 (5)	0.0109 (4)	−0.0016 (4)	0.0013 (3)	0.0000 (4)
N1	0.0177 (4)	0.0123 (5)	0.0106 (4)	−0.0005 (3)	0.0009 (3)	0.0017 (3)
N2	0.0292 (5)	0.0162 (5)	0.0100 (4)	0.0049 (4)	0.0009 (3)	−0.0003 (4)
C1	0.0164 (4)	0.0130 (5)	0.0104 (4)	−0.0015 (4)	0.0017 (3)	0.0018 (4)
C2	0.0175 (4)	0.0135 (6)	0.0123 (4)	0.0005 (4)	0.0012 (3)	0.0027 (4)
C3	0.0138 (4)	0.0133 (6)	0.0152 (4)	−0.0010 (4)	0.0016 (3)	0.0007 (4)
C4	0.0161 (4)	0.0164 (6)	0.0130 (4)	−0.0008 (4)	0.0012 (3)	−0.0014 (4)
C5	0.0169 (4)	0.0161 (6)	0.0099 (4)	−0.0021 (4)	0.0012 (3)	0.0001 (4)
C6	0.0199 (5)	0.0158 (6)	0.0228 (5)	0.0032 (4)	0.0024 (4)	0.0010 (4)

Geometric parameters (Å, º)

Cl1—C10	1.7383 (13)	N1—H1A	0.8600
O1—C13	1.2643 (14)	N2—C1	1.3280 (18)
O2—C13	1.2593 (14)	N2—H2B	0.8600
C7—C8	1.3934 (19)	N2—H2C	0.8600
C7—C12	1.3972 (16)	C1—C2	1.4138 (18)
C7—H7A	0.9300	C2—C3	1.3779 (16)
C8—C9	1.3909 (19)	C2—H2A	0.9300
C8—H8A	0.9300	C3—C4	1.4170 (16)
C9—C10	1.3927 (17)	C3—C6	1.5019 (19)
C9—H9A	0.9300	C4—C5	1.3599 (18)
C10—C11	1.3849 (19)	C4—H4A	0.9300
C11—C12	1.3968 (17)	C5—H5A	0.9300
C11—H11A	0.9300	C6—H6A	0.9600
C12—C13	1.5134 (18)	C6—H6B	0.9600
N1—C1	1.3582 (14)	C6—H6C	0.9600
N1—C5	1.3636 (15)
C8—C7—C12	120.35 (12)	C1—N2—H2B	120.0
C8—C7—H7A	119.8	C1—N2—H2C	120.0
C12—C7—H7A	119.8	H2B—N2—H2C	120.0
C9—C8—C7	120.21 (11)	N2—C1—N1	118.49 (12)
C9—C8—H8A	119.9	N2—C1—C2	122.93 (11)
C7—C8—H8A	119.9	N1—C1—C2	118.57 (11)
C8—C9—C10	118.87 (12)	C3—C2—C1	120.36 (10)
C8—C9—H9A	120.6	C3—C2—H2A	119.8
C10—C9—H9A	120.6	C1—C2—H2A	119.8
C11—C10—C9	121.68 (12)	C2—C3—C4	118.91 (11)
C11—C10—Cl1	119.30 (9)	C2—C3—C6	120.86 (11)
C9—C10—Cl1	119.01 (10)	C4—C3—C6	120.22 (11)
C10—C11—C12	119.26 (11)	C5—C4—C3	119.42 (11)
C10—C11—H11A	120.4	C5—C4—H4A	120.3
C12—C11—H11A	120.4	C3—C4—H4A	120.3
C11—C12—C7	119.63 (12)	C4—C5—N1	121.04 (11)
C11—C12—C13	119.90 (10)	C4—C5—H5A	119.5
C7—C12—C13	120.47 (11)	N1—C5—H5A	119.5
O2—C13—O1	125.07 (12)	C3—C6—H6A	109.5
O2—C13—C12	117.52 (10)	C3—C6—H6B	109.5
O1—C13—C12	117.41 (10)	H6A—C6—H6B	109.5
C1—N1—C5	121.66 (11)	C3—C6—H6C	109.5
C1—N1—H1A	119.2	H6A—C6—H6C	109.5
C5—N1—H1A	119.2	H6B—C6—H6C	109.5
C12—C7—C8—C9	−0.62 (19)	C11—C12—C13—O1	179.10 (11)
C7—C8—C9—C10	−0.5 (2)	C7—C12—C13—O1	0.27 (16)
C8—C9—C10—C11	0.9 (2)	C5—N1—C1—N2	178.68 (11)
C8—C9—C10—Cl1	−178.18 (10)	C5—N1—C1—C2	−2.06 (17)
C9—C10—C11—C12	−0.32 (18)	N2—C1—C2—C3	−179.79 (12)
Cl1—C10—C11—C12	178.81 (9)	N1—C1—C2—C3	0.98 (17)
C10—C11—C12—C7	−0.79 (17)	C1—C2—C3—C4	0.97 (17)
C10—C11—C12—C13	−179.62 (10)	C1—C2—C3—C6	−178.29 (10)
C8—C7—C12—C11	1.26 (18)	C2—C3—C4—C5	−1.91 (17)
C8—C7—C12—C13	−179.91 (11)	C6—C3—C4—C5	177.35 (11)
C11—C12—C13—O2	−1.50 (17)	C3—C4—C5—N1	0.90 (17)
C7—C12—C13—O2	179.67 (11)	C1—N1—C5—C4	1.13 (17)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1^i	0.86	1.83	2.6921 (16)	175
N2—H2B···O2^i	0.86	1.93	2.786 (2)	177
N2—H2C···O2^ii	0.86	1.96	2.8146 (14)	173
C5—H5A···O1^iii	0.93	2.50	3.1707 (13)	129

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