2-Amino-3-methyl­pyridinium 4-meth­oxy­benzoate

Sivakumar, P.; Devi, R.N.; Israel, S.; Chakkaravarthi, G.

doi:10.1107/S2414314616011263

organic compounds

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ISSN: 2414-3146

Volume 1| Part 7| July 2016| x161126

https://doi.org/10.1107/S2414314616011263

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2-Amino-3-methylpyridinium 4-methoxybenzoate

P. Sivakumar,^a,^b R. Niranjana Devi,^c S. Israel ^c ^* and G. Chakkaravarthi ^b ^*

^aResearch and Development Centre, Bharathiar University, Coimbatore 641 046, India, ^bDepartment of Physics, CPCL Polytechnic College, Chennai 600 068, India, and ^cPostgraduate and Research Department of Physics, The American College, Madurai 625 002, India
^*Correspondence e-mail: israel.samuel@gmail.com, chakkaravarthi_2005@yahoo.com

Edited by H. Stoeckli-Evans, University of Neuchâtel, Switzerland (Received 3 July 2016; accepted 11 July 2016; online 19 July 2016)

In the title molecular salt, C₆H₉N₂⁺·C₈H₇O₃⁻, the cation is protonated at its pyridine N atom and is inclined by 3.39 (9)° to the benzene ring of the anion, which is deprotonated at the carboxyl group. The methoxy group is twisted with respect to the benzene ring to which it is attached, the methyl C atom deviating from the ring plane by 0.023 (2) Å. In the crystal, the anions and cations are linked by two N—H⋯O hydrogen bonds, forming an R₂²(8) ring motif. They are also linked by a weak offset π–π interaction [centroid-to-centroid distance = 3.890 (1) Å]. The anions and cations are further connected through N—H⋯O and C—H⋯O hydrogen bonds, forming slabs parallel to (001).

Keywords: crystal structure; molecular salt; offset π-π interactions; hydrogen bonding.

CCDC reference: 1491857

Structure description

Pyridine derivatives have been shown to exhibit anticancer (Girgis et al. 2006 ) and antiviral (Hamdouchi et al., 1999 ) activities. As part of our studies in this area we synthesized the title compound and report herein on its synthesis and crystal structure.

The geometric parameters of the title compound, Fig. 1, are comparable with those reported for similar structures (Babu et al., 2014 ; Sivakumar et al., 2016 ). The asymmetric unit contains a 2-amino-3-methylpyridinium cation, which is protonated at the pyridine N atom and a 4-methoxybenzoate anion which is deprotonated at the carboxyl group. They are linked by two N—H⋯O hydrogen bonds, forming R₂²(8) ring-motifs (Table 1 and Fig. 2). They are also linked by a weak offset π–π interaction [Cg1⋯Cg2 = 3.890 (1) Å, interplanar distance = 3.487 (1) Å, slippage = 1.896 Å, Cg1 and Cg2 are the centroids of rings C1–C6 and N1/C9–C13, respectively]. The benzene ring (C1–C6) makes a dihedral angle of 3.39 (9)° with the pyridine ring (N1/C9–C13). The methoxy group is twisted with respect to the benzene ring, the methyl atom C17 deviating from the ring plane by 0.023 (2) Å. The mean plane of the methoxy group (C1/O1/C7) is twisted at an angle of 3.49 (17)° with respect to the attached benzene ring.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O2ⁱ	0.89 (1)	1.69 (1)	2.573 (2)	174 (2)
N2—H2A⋯O3ⁱ	0.86	2.01	2.8680 (19)	175
N2—H2B⋯O3ⁱⁱ	0.86	2.12	2.924 (2)	155
C2—H2⋯O2ⁱⁱⁱ	0.93	2.57	3.419 (2)	152
C10—H10⋯O1^iv	0.93	2.59	3.356 (2)	140
Symmetry codes: (i) x, y+1, z; (ii) $[-x+{\script{5\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) $[-x+{\script{3\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Figure 1
The molecular structure of the title molecular salt, showing the atom labelling and 30% probability displacement ellipsoids.

Figure 2
A partial view of the crystal packing of the title molecular salt, showing the R₂²(8) ring motifs. The hydrogen bonds are shown as dashed lines (see Table 1

for details).

In the crystal, the anions and cations are further connected through N—H⋯O and C—H⋯O hydrogen bonds, forming slabs parallel to the ab plane (Table 1 and Fig. 3).

Figure 3
The crystal packing of the title compound viewed along the a axis. The hydrogen bonds are shown as dashed lines. C-bound H atoms which are not involved in these interactions have been omitted for clarity.

Synthesis and crystallization

4-Methoxy benzoic acid (0.76 g) and 2-amino-3-methylpyridine (0.54 g) with 20 ml of acetone was magnetically stirred for 4 h in a round-bottomed flask, and the reaction mixture was kept for slow evaporation. Colourless block-like crystals were obtained after two weeks.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₆H₉N₂⁺·C₈H₇O₃⁻
M_r	260.29
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	295
a, b, c (Å)	12.2526 (8), 6.6872 (3), 16.6376 (12)
β (°)	103.836 (4)
V (Å³)	1323.66 (14)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.09
Crystal size (mm)	0.26 × 0.24 × 0.20

Data collection
Diffractometer	Bruker Kappa APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2004 )
T_min, T_max	0.976, 0.982
No. of measured, independent and observed [I > 2σ(I)] reflections	18167, 3737, 2223
R_int	0.037
(sin θ/λ)_max (Å⁻¹)	0.697

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.053, 0.151, 1.08
No. of reflections	3737
No. of parameters	178
No. of restraints	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.18, −0.26
Computer programs: APEX2 and SAINT (Bruker, 2004), SHELXS97 and SHELXL97 (Sheldrick, 2008 ), PLATON (Spek, 2009 ) and Mercury (Macrae et al., 2008 ).

Structural data

CCDC reference: 1491857

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2414314616011263/su4062sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314616011263/su4062Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314616011263/su4062Isup3.cml

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

2-Amino-3-methylpyridinium 4-methoxybenzoate top

Crystal data top

C₆H₉N₂⁺·C₈H₇O₃⁻	F(000) = 552
M_r = 260.29	D_x = 1.306 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 3853 reflections
a = 12.2526 (8) Å	θ = 2.0–25.1°
b = 6.6872 (3) Å	µ = 0.09 mm⁻¹
c = 16.6376 (12) Å	T = 295 K
β = 103.836 (4)°	Block, colourless
V = 1323.66 (14) Å³	0.26 × 0.24 × 0.20 mm
Z = 4

Data collection top

Bruker Kappa APEXII CCD diffractometer	3737 independent reflections
Radiation source: fine-focus sealed tube	2223 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.037
ω and φ scan	θ_max = 29.7°, θ_min = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −17→17
T_min = 0.976, T_max = 0.982	k = −9→9
18167 measured reflections	l = −20→23

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.053	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.151	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ²(F_o²) + (0.0547P)² + 0.4113P] where P = (F_o² + 2F_c²)/3
3737 reflections	(Δ/σ)_max < 0.001
178 parameters	Δρ_max = 0.18 e Å⁻³
1 restraint	Δρ_min = −0.26 e Å⁻³

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.85075 (14)	0.0076 (3)	0.11668 (11)	0.0415 (4)
C2	0.79234 (15)	−0.1179 (3)	0.15722 (12)	0.0465 (5)
H2	0.7180	−0.0899	0.1573	0.056*
C3	0.84426 (14)	−0.2841 (3)	0.19738 (12)	0.0430 (4)
H3	0.8045	−0.3678	0.2248	0.052*
C4	0.95519 (13)	−0.3300 (2)	0.19798 (10)	0.0340 (4)
C5	1.01214 (14)	−0.2014 (3)	0.15768 (12)	0.0406 (4)
H5	1.0865	−0.2289	0.1575	0.049*
C6	0.96139 (14)	−0.0324 (3)	0.11746 (12)	0.0444 (4)
H6	1.0015	0.0535	0.0912	0.053*
C7	0.8482 (2)	0.3068 (3)	0.03804 (14)	0.0610 (6)
H7A	0.9141	0.3541	0.0769	0.091*
H7B	0.7992	0.4175	0.0183	0.091*
H7C	0.8696	0.2439	−0.0077	0.091*
C8	1.00960 (13)	−0.5140 (3)	0.23994 (11)	0.0377 (4)
C9	0.95005 (15)	−0.0433 (3)	0.38533 (12)	0.0481 (5)
H9	0.8794	0.0128	0.3809	0.058*
C10	0.97554 (17)	−0.2178 (3)	0.42519 (14)	0.0564 (5)
H10	0.9234	−0.2837	0.4482	0.068*
C11	1.08219 (18)	−0.2974 (3)	0.43122 (13)	0.0516 (5)
H11	1.1013	−0.4171	0.4596	0.062*
C12	1.15932 (15)	−0.2059 (3)	0.39696 (11)	0.0403 (4)
C13	1.12801 (13)	−0.0236 (3)	0.35510 (10)	0.0357 (4)
C14	1.27304 (17)	−0.2935 (3)	0.40184 (14)	0.0560 (5)
H14A	1.2828	−0.4106	0.4362	0.084*
H14B	1.3297	−0.1969	0.4252	0.084*
H14C	1.2796	−0.3291	0.3473	0.084*
N1	1.02534 (12)	0.0519 (2)	0.35162 (10)	0.0401 (4)
N2	1.19561 (12)	0.0814 (2)	0.31892 (10)	0.0455 (4)
H2A	1.1728	0.1926	0.2947	0.055*
H2B	1.2620	0.0379	0.3199	0.055*
O1	0.79184 (12)	0.1675 (2)	0.07713 (10)	0.0602 (4)
O2	0.95301 (11)	−0.61756 (19)	0.27896 (10)	0.0536 (4)
O3	1.10690 (10)	−0.55837 (19)	0.23454 (9)	0.0515 (4)
H1	1.0056 (19)	0.169 (2)	0.3269 (14)	0.073 (7)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0378 (9)	0.0431 (10)	0.0424 (10)	0.0075 (8)	0.0071 (8)	0.0015 (8)
C2	0.0307 (8)	0.0560 (11)	0.0548 (12)	0.0073 (8)	0.0142 (8)	0.0037 (9)
C3	0.0325 (8)	0.0477 (10)	0.0517 (11)	−0.0008 (8)	0.0157 (8)	0.0036 (9)
C4	0.0301 (8)	0.0338 (8)	0.0387 (9)	−0.0003 (6)	0.0094 (7)	−0.0040 (7)
C5	0.0286 (8)	0.0437 (10)	0.0514 (11)	0.0021 (7)	0.0134 (7)	0.0013 (8)
C6	0.0365 (9)	0.0461 (10)	0.0528 (12)	−0.0018 (8)	0.0149 (8)	0.0079 (9)
C7	0.0735 (15)	0.0456 (11)	0.0607 (14)	0.0047 (11)	0.0099 (11)	0.0098 (10)
C8	0.0330 (8)	0.0340 (9)	0.0478 (10)	−0.0003 (7)	0.0130 (7)	−0.0042 (8)
C9	0.0357 (9)	0.0589 (12)	0.0514 (12)	−0.0015 (8)	0.0139 (8)	−0.0008 (10)
C10	0.0487 (11)	0.0648 (13)	0.0602 (14)	−0.0108 (10)	0.0219 (10)	0.0088 (11)
C11	0.0584 (12)	0.0463 (11)	0.0507 (12)	−0.0022 (9)	0.0144 (9)	0.0097 (9)
C12	0.0406 (9)	0.0416 (9)	0.0375 (10)	0.0019 (8)	0.0068 (7)	0.0011 (8)
C13	0.0334 (8)	0.0381 (9)	0.0348 (9)	−0.0029 (7)	0.0066 (7)	−0.0037 (7)
C14	0.0520 (11)	0.0566 (12)	0.0598 (13)	0.0170 (10)	0.0138 (10)	0.0111 (10)
N1	0.0356 (7)	0.0402 (8)	0.0450 (9)	0.0013 (6)	0.0106 (6)	0.0010 (7)
N2	0.0344 (7)	0.0430 (8)	0.0615 (11)	0.0054 (6)	0.0166 (7)	0.0108 (7)
O1	0.0490 (8)	0.0609 (9)	0.0712 (10)	0.0175 (7)	0.0152 (7)	0.0210 (8)
O2	0.0435 (7)	0.0443 (7)	0.0809 (11)	0.0060 (6)	0.0302 (7)	0.0153 (7)
O3	0.0378 (7)	0.0470 (7)	0.0757 (10)	0.0092 (6)	0.0255 (7)	0.0111 (7)

Geometric parameters (Å, º) top

C1—O1	1.367 (2)	C9—C10	1.341 (3)
C1—C6	1.379 (2)	C9—N1	1.348 (2)
C1—C2	1.379 (3)	C9—H9	0.9300
C2—C3	1.372 (3)	C10—C11	1.392 (3)
C2—H2	0.9300	C10—H10	0.9300
C3—C4	1.391 (2)	C11—C12	1.360 (3)
C3—H3	0.9300	C11—H11	0.9300
C4—C5	1.378 (2)	C12—C13	1.411 (2)
C4—C8	1.491 (2)	C12—C14	1.495 (3)
C5—C6	1.383 (2)	C13—N2	1.334 (2)
C5—H5	0.9300	C13—N1	1.344 (2)
C6—H6	0.9300	C14—H14A	0.9600
C7—O1	1.408 (3)	C14—H14B	0.9600
C7—H7A	0.9600	C14—H14C	0.9600
C7—H7B	0.9600	N1—H1	0.888 (9)
C7—H7C	0.9600	N2—H2A	0.8600
C8—O3	1.2525 (19)	N2—H2B	0.8600
C8—O2	1.264 (2)

O1—C1—C6	124.11 (17)	C10—C9—H9	119.5
O1—C1—C2	115.78 (16)	N1—C9—H9	119.5
C6—C1—C2	120.10 (17)	C9—C10—C11	118.15 (18)
C3—C2—C1	119.77 (16)	C9—C10—H10	120.9
C3—C2—H2	120.1	C11—C10—H10	120.9
C1—C2—H2	120.1	C12—C11—C10	122.14 (19)
C2—C3—C4	121.36 (17)	C12—C11—H11	118.9
C2—C3—H3	119.3	C10—C11—H11	118.9
C4—C3—H3	119.3	C11—C12—C13	117.47 (16)
C5—C4—C3	117.81 (16)	C11—C12—C14	122.21 (18)
C5—C4—C8	121.39 (14)	C13—C12—C14	120.31 (16)
C3—C4—C8	120.79 (15)	N2—C13—N1	117.31 (16)
C4—C5—C6	121.59 (15)	N2—C13—C12	123.54 (15)
C4—C5—H5	119.2	N1—C13—C12	119.14 (15)
C6—C5—H5	119.2	C12—C14—H14A	109.5
C1—C6—C5	119.36 (17)	C12—C14—H14B	109.5
C1—C6—H6	120.3	H14A—C14—H14B	109.5
C5—C6—H6	120.3	C12—C14—H14C	109.5
O1—C7—H7A	109.5	H14A—C14—H14C	109.5
O1—C7—H7B	109.5	H14B—C14—H14C	109.5
H7A—C7—H7B	109.5	C13—N1—C9	122.09 (16)
O1—C7—H7C	109.5	C13—N1—H1	119.9 (16)
H7A—C7—H7C	109.5	C9—N1—H1	118.0 (16)
H7B—C7—H7C	109.5	C13—N2—H2A	120.0
O3—C8—O2	123.74 (16)	C13—N2—H2B	120.0
O3—C8—C4	119.25 (15)	H2A—N2—H2B	120.0
O2—C8—C4	117.00 (14)	C1—O1—C7	118.63 (15)
C10—C9—N1	120.98 (18)

O1—C1—C2—C3	178.87 (17)	N1—C9—C10—C11	0.4 (3)
C6—C1—C2—C3	−0.9 (3)	C9—C10—C11—C12	−1.2 (3)
C1—C2—C3—C4	−0.2 (3)	C10—C11—C12—C13	0.7 (3)
C2—C3—C4—C5	0.8 (3)	C10—C11—C12—C14	−178.7 (2)
C2—C3—C4—C8	−178.34 (17)	C11—C12—C13—N2	179.89 (17)
C3—C4—C5—C6	−0.3 (3)	C14—C12—C13—N2	−0.8 (3)
C8—C4—C5—C6	178.86 (17)	C11—C12—C13—N1	0.7 (3)
O1—C1—C6—C5	−178.34 (18)	C14—C12—C13—N1	−179.99 (17)
C2—C1—C6—C5	1.4 (3)	N2—C13—N1—C9	179.22 (16)
C4—C5—C6—C1	−0.8 (3)	C12—C13—N1—C9	−1.5 (3)
C5—C4—C8—O3	−4.0 (3)	C10—C9—N1—C13	1.0 (3)
C3—C4—C8—O3	175.11 (17)	C6—C1—O1—C7	−3.4 (3)
C5—C4—C8—O2	176.43 (17)	C2—C1—O1—C7	176.88 (18)
C3—C4—C8—O2	−4.5 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O2ⁱ	0.89 (1)	1.69 (1)	2.573 (2)	174 (2)
N2—H2A···O3ⁱ	0.86	2.01	2.8680 (19)	175
N2—H2B···O3ⁱⁱ	0.86	2.12	2.924 (2)	155
C2—H2···O2ⁱⁱⁱ	0.93	2.57	3.419 (2)	152
C10—H10···O1^iv	0.93	2.59	3.356 (2)	140

Symmetry codes: (i) x, y+1, z; (ii) −x+5/2, y+1/2, −z+1/2; (iii) −x+3/2, y+1/2, −z+1/2; (iv) −x+3/2, y−1/2, −z+1/2.

Acknowledgements

The authors acknowledge the SAIF, IIT, Madras, for the data collection.

References

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