2-Amino-4-methyl­pyridinium 4-meth­oxy­benzoate dihydrate

Sivakumar, P.; Ezhamani, G.; Israel, S.; Chakkaravarthi, G.

doi:10.1107/S2414314617006496

organic compounds

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ISSN: 2414-3146

Volume 2| Part 5| May 2017| x170649

https://doi.org/10.1107/S2414314617006496

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2-Amino-4-methylpyridinium 4-methoxybenzoate dihydrate

P. Sivakumar,^a,^b G. Ezhamani,^c S. Israel ^d ^* and G. Chakkaravarthi ^b ^*

^aResearch and Development Centre, Bharathiar University, Coimbatore 641 046, India, ^bDepartment of Physics, CPCL Polytechnic College, Chennai 600 068, India, ^cPost Graduate and Research Department of Physics, Govt Arts College for Men, Nandanam, Chennai 600 025, India, and ^dPost Graduate 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 W. T. A. Harrison, University of Aberdeen, Scotland (Received 15 April 2017; accepted 30 April 2017; online 5 May 2017)

In the title hydrated molecular salt, C₆H₉N₂⁺·C₈H₇O₃⁻·2H₂O, the cation is protonated at the pyridine N atom. The cation and anion are linked by a pair of N—H⋯O hydrogen bonds, which generates an R₂²(8) loop, and the dihedral angle between their ring planes is 16.07 (14)°. The ion pairs are linked by O—H⋯O hydrogen bonds involving the water molecules, generating a three-dimensional network. Weak C—H⋯O and aromatic π–π stacking [centroid-to-centroid distance = 3.5874 (17) Å] interactions are also observed.

Keywords: crystal structure; molecular salt; hydrogen bonding.

CCDC reference: 1547046

Structure description

We herewith report the synthesis and the crystal structure of the title hydrated molecular salt (Fig. 1). The bond lengths are comparable with reported similar structures (Sivakumar et al., 2016a ,b ). The cation is protonated at the pyridine N atom and the dihedral angle between the pyridine (N1/C9–C13) and benzene (C2–C7) rings is 16.07 (14)°.

Figure 1
The molecular structure of the title molecular salt, with 30% probability displacement ellipsoids. Hydrogen bonds are shown as dashed lines.

In the asymmetric unit, N1—H1⋯O1 and N2—H2B⋯O2 hydrogen bonds link the anion and cation and generate an $[R_{2}^{2}]$ (8) loop. The ion-pairs are further connected with the water molecules of crystallization through O4—H4A⋯O2 and O5—H5A⋯O1 hydrogen bonds (Fig. 1 and Table 1). Further O—H⋯O hydrogen bonds link the components into a three-dimensional network (Fig. 2). Weak C—H⋯O and π–π [Cg2⋯Cg2(−x, y, 1 − z) = 3.5874 (17) Å; Cg2 is the centroid of the N1/C9–C13 ring] interactions are also observed.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O1	0.87 (1)	1.87 (1)	2.737 (3)	175 (4)
N2—H2B⋯O2	0.87 (1)	1.91 (2)	2.758 (3)	165 (4)
N2—H2A⋯O5ⁱ	0.86 (1)	2.10 (2)	2.951 (3)	169 (3)
O4—H4A⋯O2	0.82 (1)	1.92 (2)	2.743 (3)	173 (5)
O4—H4B⋯O4ⁱⁱ	0.81 (1)	2.45 (2)	2.788 (6)	107 (1)
O5—H5A⋯O1	0.83 (1)	1.94 (2)	2.764 (3)	173 (4)
O5—H5B⋯O4ⁱⁱⁱ	0.82 (1)	2.01 (2)	2.814 (3)	168 (4)
C6—H6⋯O4^iv	0.93	2.57	3.455 (4)	160
Symmetry codes: (i) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+1]$ ; (ii) -x, y, -z; (iii) $[x+{\script{1\over 2}}, y+{\script{1\over 2}}, z]$ ; (iv) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z]$ .

Figure 2
The crystal packing of the title molecular salt viewed along a axis. Hydrogen bonds are shown as dashed lines. H atoms not involving in hydrogen bonds have been omitted for clarity.

Synthesis and crystallization

The title compound was prepared by mixing 4-methoxy benzoic acid (0.76 g) and 2-amino-4-methylpyridine (0.54 g) in an equimolar ratio in 20 ml acetone: the mixture was magnetically stirred for 3 h in a round-bottomed flask and then kept at room temperature for slow evaporation. After 30 days, colourless blocks were harvested.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. The water H atoms were located in difference maps but DFIX and DANG commands were required to stabilize their refinement and prevent unreasonable close contacts and the location of these atoms should be regarded as less certain.

Table 2
Experimental details

Crystal data
Chemical formula	C₆H₉N₂⁺·C₈H₇O₃⁻·2H₂O
M_r	296.32
Crystal system, space group	Monoclinic, C2
Temperature (K)	295
a, b, c (Å)	13.6968 (12), 12.1053 (10), 9.6353 (7)
β (°)	105.170 (3)
V (Å³)	1541.9 (2)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.10
Crystal size (mm)	0.28 × 0.24 × 0.20

Data collection
Diffractometer	Bruker Kappa APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2004 )
T_min, T_max	0.694, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	15843, 4821, 2891
R_int	0.048
(sin θ/λ)_max (Å⁻¹)	0.725

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.046, 0.133, 1.02
No. of reflections	4821
No. of parameters	217
No. of restraints	10
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.17, −0.16
Computer programs: APEX2 and SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008 ), SHELXL2016 (Sheldrick, 2015 ) and PLATON (Spek, 2009 ).

Structural data

CCDC reference: 1547046

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S2414314617006496/hb4140sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314617006496/hb4140Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314617006496/hb4140Isup3.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: SHELXL2016 (Sheldrick, 2015); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL2016 (Sheldrick, 2015) and PLATON (Spek, 2009).

2-Amino-4-methylpyridinium 4-methoxybenzoate dihydrate top

Crystal data top

C₆H₉N₂⁺·C₈H₇O₃⁻·2H₂O	F(000) = 632
M_r = 296.32	D_x = 1.276 Mg m⁻³
Monoclinic, C2	Mo Kα radiation, λ = 0.71073 Å
a = 13.6968 (12) Å	Cell parameters from 4368 reflections
b = 12.1053 (10) Å	θ = 2.6–25.0°
c = 9.6353 (7) Å	µ = 0.10 mm⁻¹
β = 105.170 (3)°	T = 295 K
V = 1541.9 (2) Å³	Block, colourless
Z = 4	0.28 × 0.24 × 0.20 mm

Data collection top

Bruker Kappa APEXII CCD diffractometer	2891 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.048
ω and φ scan	θ_max = 31.0°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −19→19
T_min = 0.694, T_max = 0.746	k = −17→17
15843 measured reflections	l = −11→13
4821 independent reflections

Refinement top

Refinement on F²	Hydrogen site location: mixed
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F² > 2σ(F²)] = 0.046	w = 1/[σ²(F_o²) + (0.060P)² + 0.0879P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.133	(Δ/σ)_max < 0.001
S = 1.02	Δρ_max = 0.17 e Å⁻³
4821 reflections	Δρ_min = −0.16 e Å⁻³
217 parameters	Extinction correction: SHELXL2016 (Sheldrick, 2015), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
10 restraints	Extinction coefficient: 0.0095 (18)
Primary atom site location: structure-invariant direct methods

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. The hydrogen atoms for the NH and NH₂ groups were loacated from Fourier maps and refined with N—H distance restraints of 0.86 (1) Å. The C-bound H atoms were positioned geometrically and refined using a riding model, with C—H = 0.93 Å and U_iso(H) = 1.2Ueq(C) for aromatic CH and C—H = 0.96 Å and U_iso(H) = 1.5Ueq(C) for CH₃.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.2345 (2)	0.6229 (2)	0.2107 (3)	0.0483 (6)
C2	0.27037 (19)	0.6036 (2)	0.0794 (3)	0.0405 (5)
C3	0.2511 (2)	0.5037 (2)	0.0058 (3)	0.0510 (6)
H3	0.213561	0.449829	0.037537	0.061*
C4	0.2863 (2)	0.4830 (2)	−0.1125 (3)	0.0537 (7)
H4	0.273219	0.415525	−0.159883	0.064*
C5	0.34132 (19)	0.5633 (2)	−0.1606 (3)	0.0458 (6)
C6	0.3602 (2)	0.6642 (2)	−0.0921 (3)	0.0481 (6)
H6	0.396041	0.718693	−0.125850	0.058*
C7	0.3245 (2)	0.6827 (2)	0.0280 (3)	0.0458 (6)
H7	0.337494	0.750201	0.075218	0.055*
C8	0.4287 (3)	0.6162 (3)	−0.3348 (4)	0.0772 (10)
H8A	0.389868	0.683038	−0.354442	0.116*
H8B	0.441904	0.589405	−0.421898	0.116*
H8C	0.491630	0.630678	−0.265095	0.116*
C9	0.13362 (18)	0.6428 (3)	0.5632 (3)	0.0484 (6)
C10	0.0920 (2)	0.6643 (3)	0.6788 (3)	0.0550 (7)
H10	0.068893	0.606065	0.724535	0.066*
C11	0.0851 (2)	0.7694 (3)	0.7244 (3)	0.0584 (7)
C12	0.1220 (3)	0.8565 (3)	0.6556 (4)	0.0668 (8)
H12	0.118150	0.929002	0.685539	0.080*
C13	0.1631 (2)	0.8337 (3)	0.5456 (3)	0.0606 (8)
H13	0.188020	0.890841	0.500152	0.073*
C14	0.0384 (3)	0.7919 (4)	0.8469 (4)	0.0876 (12)
H14A	−0.006539	0.732559	0.854159	0.131*
H14B	0.001103	0.859920	0.829460	0.131*
H14C	0.090709	0.797567	0.935051	0.131*
N1	0.16822 (17)	0.7284 (2)	0.5012 (2)	0.0500 (6)
H1	0.198 (2)	0.718 (3)	0.433 (3)	0.077 (11)*
N2	0.1394 (2)	0.5422 (2)	0.5105 (3)	0.0607 (7)
H2A	0.123 (3)	0.488 (2)	0.558 (3)	0.075 (11)*
H2B	0.156 (3)	0.533 (3)	0.430 (2)	0.071 (10)*
O1	0.26234 (15)	0.70839 (18)	0.2845 (2)	0.0614 (6)
O2	0.1790 (2)	0.5517 (2)	0.2445 (3)	0.0845 (8)
O3	0.37349 (16)	0.5352 (2)	−0.2798 (2)	0.0663 (6)
O4	0.0223 (2)	0.4061 (2)	0.1497 (3)	0.0846 (8)
H4A	0.068 (2)	0.452 (3)	0.171 (5)	0.127*
H4B	−0.0250 (18)	0.439 (4)	0.0997 (15)	0.127*
O5	0.43049 (16)	0.84316 (18)	0.3669 (2)	0.0596 (5)
H5A	0.383 (2)	0.799 (3)	0.340 (4)	0.089*
H5B	0.465 (3)	0.859 (4)	0.312 (4)	0.089*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0507 (14)	0.0501 (16)	0.0493 (14)	−0.0098 (12)	0.0220 (12)	−0.0039 (13)
C2	0.0419 (12)	0.0418 (13)	0.0395 (13)	−0.0052 (10)	0.0138 (10)	−0.0023 (10)
C3	0.0596 (14)	0.0461 (16)	0.0529 (15)	−0.0147 (12)	0.0249 (12)	−0.0041 (12)
C4	0.0670 (17)	0.0479 (15)	0.0502 (15)	−0.0094 (13)	0.0224 (13)	−0.0117 (12)
C5	0.0434 (13)	0.0543 (16)	0.0413 (13)	−0.0038 (11)	0.0143 (11)	−0.0042 (12)
C6	0.0540 (15)	0.0504 (16)	0.0438 (14)	−0.0099 (12)	0.0199 (11)	−0.0006 (11)
C7	0.0513 (14)	0.0414 (14)	0.0480 (15)	−0.0094 (11)	0.0186 (11)	−0.0062 (11)
C8	0.082 (2)	0.099 (3)	0.0652 (19)	−0.016 (2)	0.0454 (18)	−0.006 (2)
C9	0.0411 (12)	0.0630 (17)	0.0408 (13)	0.0006 (12)	0.0099 (10)	0.0049 (13)
C10	0.0478 (14)	0.075 (2)	0.0431 (14)	−0.0046 (14)	0.0139 (11)	0.0086 (13)
C11	0.0492 (15)	0.083 (2)	0.0456 (15)	−0.0021 (15)	0.0165 (12)	−0.0088 (15)
C12	0.075 (2)	0.066 (2)	0.0635 (19)	−0.0022 (16)	0.0252 (16)	−0.0126 (17)
C13	0.0670 (19)	0.0617 (19)	0.0565 (17)	−0.0098 (15)	0.0226 (14)	−0.0036 (15)
C14	0.086 (2)	0.125 (3)	0.063 (2)	−0.005 (2)	0.0386 (19)	−0.021 (2)
N1	0.0518 (12)	0.0579 (14)	0.0446 (13)	−0.0047 (10)	0.0201 (10)	−0.0010 (11)
N2	0.0752 (17)	0.0586 (16)	0.0549 (15)	0.0007 (13)	0.0289 (13)	0.0080 (13)
O1	0.0736 (13)	0.0623 (12)	0.0597 (12)	−0.0203 (10)	0.0380 (10)	−0.0208 (10)
O2	0.1166 (19)	0.0796 (16)	0.0798 (16)	−0.0489 (15)	0.0659 (15)	−0.0271 (14)
O3	0.0743 (13)	0.0787 (14)	0.0568 (11)	−0.0145 (11)	0.0365 (10)	−0.0150 (11)
O4	0.0782 (16)	0.0847 (18)	0.0918 (18)	−0.0235 (14)	0.0238 (13)	−0.0047 (15)
O5	0.0634 (13)	0.0619 (13)	0.0570 (12)	−0.0125 (10)	0.0220 (10)	−0.0108 (10)

Geometric parameters (Å, º) top

C1—O2	1.247 (3)	C9—C10	1.401 (4)
C1—O1	1.257 (3)	C10—C11	1.357 (5)
C1—C2	1.491 (3)	C10—H10	0.9300
C2—C7	1.380 (3)	C11—C12	1.407 (5)
C2—C3	1.391 (4)	C11—C14	1.508 (4)
C3—C4	1.372 (4)	C12—C13	1.352 (4)
C3—H3	0.9300	C12—H12	0.9300
C4—C5	1.382 (4)	C13—N1	1.352 (4)
C4—H4	0.9300	C13—H13	0.9300
C5—O3	1.376 (3)	C14—H14A	0.9600
C5—C6	1.381 (4)	C14—H14B	0.9600
C6—C7	1.387 (3)	C14—H14C	0.9600
C6—H6	0.9300	N1—H1	0.870 (13)
C7—H7	0.9300	N2—H2A	0.864 (14)
C8—O3	1.422 (4)	N2—H2B	0.868 (13)
C8—H8A	0.9600	O4—H4A	0.823 (14)
C8—H8B	0.9600	O4—H4B	0.805 (14)
C8—H8C	0.9600	O5—H5A	0.830 (14)
C9—N2	1.330 (4)	O5—H5B	0.822 (14)
C9—N1	1.342 (4)

O2—C1—O1	122.4 (2)	N1—C9—C10	118.3 (3)
O2—C1—C2	118.2 (2)	C11—C10—C9	120.6 (3)
O1—C1—C2	119.4 (2)	C11—C10—H10	119.7
C7—C2—C3	117.9 (2)	C9—C10—H10	119.7
C7—C2—C1	121.6 (2)	C10—C11—C12	119.0 (3)
C3—C2—C1	120.5 (2)	C10—C11—C14	120.2 (3)
C4—C3—C2	121.4 (2)	C12—C11—C14	120.8 (3)
C4—C3—H3	119.3	C13—C12—C11	119.4 (3)
C2—C3—H3	119.3	C13—C12—H12	120.3
C3—C4—C5	119.4 (2)	C11—C12—H12	120.3
C3—C4—H4	120.3	C12—C13—N1	120.4 (3)
C5—C4—H4	120.3	C12—C13—H13	119.8
O3—C5—C6	123.8 (2)	N1—C13—H13	119.8
O3—C5—C4	115.4 (2)	C11—C14—H14A	109.5
C6—C5—C4	120.8 (2)	C11—C14—H14B	109.5
C5—C6—C7	118.6 (2)	H14A—C14—H14B	109.5
C5—C6—H6	120.7	C11—C14—H14C	109.5
C7—C6—H6	120.7	H14A—C14—H14C	109.5
C2—C7—C6	121.8 (2)	H14B—C14—H14C	109.5
C2—C7—H7	119.1	C9—N1—C13	122.2 (2)
C6—C7—H7	119.1	C9—N1—H1	121 (3)
O3—C8—H8A	109.5	C13—N1—H1	117 (3)
O3—C8—H8B	109.5	C9—N2—H2A	117 (2)
H8A—C8—H8B	109.5	C9—N2—H2B	121 (3)
O3—C8—H8C	109.5	H2A—N2—H2B	122 (4)
H8A—C8—H8C	109.5	C5—O3—C8	117.3 (3)
H8B—C8—H8C	109.5	H4A—O4—H4B	105 (2)
N2—C9—N1	118.3 (2)	H5A—O5—H5B	119 (4)
N2—C9—C10	123.4 (3)

O2—C1—C2—C7	174.3 (3)	C5—C6—C7—C2	−0.6 (4)
O1—C1—C2—C7	−7.1 (4)	N2—C9—C10—C11	−177.7 (3)
O2—C1—C2—C3	−6.6 (4)	N1—C9—C10—C11	1.3 (4)
O1—C1—C2—C3	172.0 (3)	C9—C10—C11—C12	−1.1 (4)
C7—C2—C3—C4	1.3 (4)	C9—C10—C11—C14	178.8 (3)
C1—C2—C3—C4	−177.9 (3)	C10—C11—C12—C13	0.2 (5)
C2—C3—C4—C5	−0.6 (5)	C14—C11—C12—C13	−179.7 (3)
C3—C4—C5—O3	180.0 (3)	C11—C12—C13—N1	0.4 (5)
C3—C4—C5—C6	−0.8 (4)	N2—C9—N1—C13	178.4 (3)
O3—C5—C6—C7	−179.5 (3)	C10—C9—N1—C13	−0.7 (4)
C4—C5—C6—C7	1.3 (4)	C12—C13—N1—C9	−0.1 (5)
C3—C2—C7—C6	−0.7 (4)	C6—C5—O3—C8	−0.4 (4)
C1—C2—C7—C6	178.5 (2)	C4—C5—O3—C8	178.8 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1	0.87 (1)	1.87 (1)	2.737 (3)	175 (4)
N2—H2B···O2	0.87 (1)	1.91 (2)	2.758 (3)	165 (4)
N2—H2A···O5ⁱ	0.86 (1)	2.10 (2)	2.951 (3)	169 (3)
O4—H4A···O2	0.82 (1)	1.92 (2)	2.743 (3)	173 (5)
O4—H4B···O4ⁱⁱ	0.81 (1)	2.45 (2)	2.788 (6)	107 (1)
O5—H5A···O1	0.83 (1)	1.94 (2)	2.764 (3)	173 (4)
O5—H5B···O4ⁱⁱⁱ	0.82 (1)	2.01 (2)	2.814 (3)	168 (4)
C6—H6···O4^iv	0.93	2.57	3.455 (4)	160

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

Acknowledgements

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

References

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