2-Amino-4-methyl­pyridinium hexa-2,4-dienoate dihydrate

In the title salt, C₆H₉N₂⁺·C₆H₇O₂⁻·2H₂O, the non-H atoms of the 2-amino-4-methyl­pyridinium cation are coplanar, with a maximum deviation of 0.010 (1) Å. In the crystal structure, the pyridinium 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 sorbate anions and water mol­ecules are linked through O—H...O hydrogen bonds, forming R₁₀¹⁰(28) and R₆⁴(12) ring motifs. The motifs form part of a three-dimensional framework.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.001 Å
• R factor = 0.044
• wR factor = 0.140
• Data-to-parameter ratio = 31.5

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.28
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          2
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         52
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....         13
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600         56

Alert level G
PLAT063_ALERT_4_G Crystal Size Likely too Large for Beam Size ....       0.66 mm
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........          7

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

   0 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
   3 ALERT type 3 Indicator that the structure quality may be low
   3 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Hydrogen bonding plays a key role in molecular recognition (Goswami & Ghosh, 1997) and crystal engineering research (Goswami et al., 1998). The design of highly specific solid-state compounds is of considerable significance in organic chemistry due to important applications of these compounds in the development of new optical, magnetic and electronic systems (Lehn, 1992). Pyridinium derivatives often possess antibacterial and antifungal activities (Akkurt et al., 2005). They are often involved in hydrogen-bonding interactions (Jeffrey & Saenger, 1991; Jeffrey, 1997; Scheiner, 1997). In order to study some hydrogen bonding interactions, the synthesis and structure of the title salt, (I), is presented here.

The asymmetric unit of (I) contains one 2-amino-4-methylpyridinium cation, one sorbate anion and two water molecules (Fig. 1). The non-H atoms of the 2-amino-4-methylpyridinium cation are coplanar, with a maximum deviation of 0.010 (1) Å for atom N1. The protonation of atom N1 has lead to a slight increase in the C1—N1—C5 angle to 121.96 (6)°. The bond lengths (Allen et al., 1987) and angles are within normal ranges.

In the crystal packing (Fig. 2), the protonated N1 atom and one of the 2-amino group hydrogen (H1N2) are hydrogen-bonded to the carboxylate oxygen atoms (O1 and O2) via a pair of intermolecular N1—H1N1···O2 and N2—H1N2···O1 hydrogen bonds forming an R₂²(8) ring motif (Bernstein et al., 1995). The sorbate anion and two water molecules are linked through O2W—H1W2···O2, O2W—H2W2···O1, O1W—H1W1···O1 and O1W—H2W1···O2W (Table 1) hydrogen-bonds, forming R₁₀¹⁰(28) and R₆⁴(12) ring motifs (Fig. 3).

Related literature

For the role of hydrogen bonding in crystal engineering, see: Goswami & Ghosh (1997); Goswami et al. (1998); Lehn (1992). For applications of pyridinium derivatives, see: Akkurt et al. (2005). 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 sorbic acid (56 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 appeared after a few days.

S3. Refinement

Atoms H1N1, H1N2, H2N2, H1W2, H2W2, H1W1 and H2W1 were located in a difference Fourier map and were refined freely [N–H= 0.911 (18)– 0.967 (17) Å and O–H= 0.84 (18)–0.87 (2) Å]. The remaining H atoms were positioned geometrically [C–H = 0.93 or 0.96 Å] and were refined using a riding model, with Uiso(H) = 1.2 or 1.5 Ueq(C). A rotating group model was used for the methyl group.

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 the title compound. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. The crystal packing of the title compound, showing part of a hydrogen-bonded (dashed lines) three-dimensional network. H atoms not involved in the interactions have been omitted for clarity.
	Fig. 3. Part of a hydrogen-bonded (dashed lines) two-dimensional network made up of anions and water molecules.

2-Amino-4-methylpyridinium hexa-2,4-dienoate dihydrate

Crystal data

C6H9N2^+·C6H7O2^−·2H2O	F(000) = 552
Mr = 256.30	Dx = 1.217 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 7645 reflections
a = 8.8233 (4) Å	θ = 2.9–34.9°
b = 12.6783 (6) Å	µ = 0.09 mm^−1
c = 13.1647 (6) Å	T = 100 K
β = 108.279 (1)°	Needle, brown
V = 1398.35 (11) Å^3	0.66 × 0.28 × 0.25 mm
Z = 4

Data collection

Bruker APEXII DUO CCD area-detector diffractometer	6087 independent reflections
Radiation source: fine-focus sealed tube	4840 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
φ and ω scans	θmax = 35.1°, θmin = 2.9°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −14→14
Tmin = 0.942, Tmax = 0.978	k = −20→20
23001 measured reflections	l = −21→21

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.140	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0809P)^2 + 0.1516P] where P = (Fo^2 + 2Fc^2)/3
6087 reflections	(Δ/σ)max = 0.001
193 parameters	Δρmax = 0.41 e Å^−3
0 restraints	Δρmin = −0.24 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 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 (Ų)

	x	y	z	Uiso*/Ueq
N1	1.07997 (7)	0.26852 (5)	0.19290 (5)	0.02127 (12)
N2	1.01177 (8)	0.43659 (6)	0.12630 (6)	0.02585 (14)
C1	1.04257 (9)	0.16859 (7)	0.21363 (7)	0.02539 (15)
H1A	1.1237	0.1224	0.2494	0.030*
C2	0.88836 (10)	0.13495 (7)	0.18292 (7)	0.02690 (16)
H2A	0.8638	0.0664	0.1974	0.032*
C3	0.76591 (9)	0.20597 (7)	0.12849 (6)	0.02333 (14)
C4	0.80544 (8)	0.30662 (6)	0.10894 (6)	0.02151 (14)
H4A	0.7257	0.3538	0.0734	0.026*
C5	0.96682 (8)	0.33929 (6)	0.14240 (6)	0.01984 (13)
C6	0.59508 (10)	0.17064 (8)	0.09388 (8)	0.03179 (18)
H6A	0.5284	0.2258	0.0535	0.048*
H6B	0.5638	0.1549	0.1558	0.048*
H6C	0.5836	0.1087	0.0502	0.048*
O1	0.35573 (6)	0.47026 (5)	0.19351 (5)	0.02451 (12)
O2	0.39446 (7)	0.30966 (5)	0.26595 (6)	0.02668 (13)
C7	0.44389 (8)	0.40024 (6)	0.25192 (6)	0.02007 (13)
C8	0.61399 (8)	0.42857 (6)	0.30428 (7)	0.02356 (15)
H8A	0.6422	0.4993	0.3054	0.028*
C9	0.72932 (8)	0.35883 (6)	0.34995 (6)	0.02082 (13)
H9A	0.7010	0.2886	0.3538	0.025*
C10	0.89651 (8)	0.38771 (7)	0.39373 (6)	0.02347 (14)
H10A	0.9226	0.4589	0.3960	0.028*
C11	1.01497 (9)	0.31857 (7)	0.43086 (6)	0.02396 (15)
H11A	0.9882	0.2476	0.4307	0.029*
C12	1.18754 (9)	0.34726 (8)	0.47266 (7)	0.02996 (18)
H12A	1.2317	0.3219	0.5446	0.045*
H12B	1.1986	0.4226	0.4719	0.045*
H12C	1.2434	0.3158	0.4284	0.045*
O1W	0.75170 (8)	0.57495 (6)	0.03208 (6)	0.03181 (15)
O2W	0.51394 (8)	0.62847 (5)	0.11569 (6)	0.03052 (14)
H1N1	1.192 (2)	0.2876 (12)	0.2177 (14)	0.047 (4)*
H1N2	1.118 (2)	0.4529 (13)	0.1473 (14)	0.049 (4)*
H2N2	0.9370 (19)	0.4873 (12)	0.0898 (13)	0.042 (4)*
H1W2	0.529 (2)	0.6833 (14)	0.1552 (15)	0.051 (4)*
H2W2	0.468 (2)	0.5855 (14)	0.1483 (13)	0.049 (4)*
H1W1	0.7068 (19)	0.5623 (12)	−0.0331 (14)	0.041 (4)*
H2W1	0.672 (2)	0.5876 (14)	0.0553 (16)	0.061 (5)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0137 (2)	0.0268 (3)	0.0213 (3)	0.0011 (2)	0.00269 (19)	−0.0009 (2)
N2	0.0161 (3)	0.0250 (3)	0.0347 (4)	0.0000 (2)	0.0054 (2)	0.0003 (3)
C1	0.0194 (3)	0.0278 (3)	0.0252 (3)	0.0014 (2)	0.0017 (3)	0.0030 (3)
C2	0.0219 (3)	0.0289 (4)	0.0267 (3)	−0.0031 (3)	0.0031 (3)	0.0042 (3)
C3	0.0158 (3)	0.0327 (4)	0.0203 (3)	−0.0031 (2)	0.0038 (2)	0.0002 (3)
C4	0.0125 (3)	0.0294 (3)	0.0216 (3)	0.0009 (2)	0.0038 (2)	−0.0002 (2)
C5	0.0139 (3)	0.0252 (3)	0.0199 (3)	0.0011 (2)	0.0046 (2)	−0.0023 (2)
C6	0.0178 (3)	0.0439 (5)	0.0312 (4)	−0.0086 (3)	0.0041 (3)	0.0033 (3)
O1	0.0151 (2)	0.0244 (3)	0.0303 (3)	0.00155 (18)	0.00176 (19)	0.0031 (2)
O2	0.0139 (2)	0.0262 (3)	0.0363 (3)	−0.00069 (18)	0.0026 (2)	0.0061 (2)
C7	0.0130 (2)	0.0238 (3)	0.0224 (3)	0.0010 (2)	0.0039 (2)	−0.0004 (2)
C8	0.0134 (3)	0.0252 (3)	0.0292 (3)	−0.0009 (2)	0.0027 (2)	0.0005 (3)
C9	0.0137 (3)	0.0264 (3)	0.0218 (3)	0.0000 (2)	0.0047 (2)	0.0005 (2)
C10	0.0134 (3)	0.0282 (3)	0.0268 (3)	−0.0005 (2)	0.0034 (2)	0.0012 (3)
C11	0.0143 (3)	0.0332 (4)	0.0230 (3)	0.0010 (2)	0.0038 (2)	0.0006 (3)
C12	0.0128 (3)	0.0450 (5)	0.0293 (4)	0.0016 (3)	0.0026 (3)	0.0013 (3)
O1W	0.0235 (3)	0.0377 (3)	0.0302 (3)	0.0067 (2)	0.0027 (2)	−0.0046 (3)
O2W	0.0328 (3)	0.0252 (3)	0.0357 (3)	−0.0037 (2)	0.0138 (3)	−0.0036 (2)

Geometric parameters (Å, º)

N1—C5	1.3518 (9)	O2—C7	1.2624 (9)
N1—C1	1.3583 (11)	C7—C8	1.4859 (10)
N1—H1N1	0.967 (17)	C8—C9	1.3397 (10)
N2—C5	1.3329 (10)	C8—H8A	0.93
N2—H1N2	0.911 (18)	C9—C10	1.4522 (10)
N2—H2N2	0.938 (16)	C9—H9A	0.93
C1—C2	1.3607 (11)	C10—C11	1.3339 (11)
C1—H1A	0.93	C10—H10A	0.93
C2—C3	1.4163 (12)	C11—C12	1.4927 (11)
C2—H2A	0.93	C11—H11A	0.93
C3—C4	1.3684 (11)	C12—H12A	0.96
C3—C6	1.4997 (11)	C12—H12B	0.96
C4—C5	1.4141 (10)	C12—H12C	0.96
C4—H4A	0.93	O1W—H1W1	0.840 (18)
C6—H6A	0.96	O1W—H2W1	0.87 (2)
C6—H6B	0.96	O2W—H1W2	0.853 (18)
C6—H6C	0.96	O2W—H2W2	0.868 (17)
O1—C7	1.2686 (9)
C5—N1—C1	121.96 (6)	H6A—C6—H6C	109.5
C5—N1—H1N1	121.1 (9)	H6B—C6—H6C	109.5
C1—N1—H1N1	116.9 (9)	O2—C7—O1	123.44 (6)
C5—N2—H1N2	119.3 (11)	O2—C7—C8	119.81 (6)
C5—N2—H2N2	121.3 (9)	O1—C7—C8	116.75 (7)
H1N2—N2—H2N2	119.3 (14)	C9—C8—C7	124.27 (7)
N1—C1—C2	121.07 (7)	C9—C8—H8A	117.9
N1—C1—H1A	119.5	C7—C8—H8A	117.9
C2—C1—H1A	119.5	C8—C9—C10	123.08 (7)
C1—C2—C3	118.95 (8)	C8—C9—H9A	118.5
C1—C2—H2A	120.5	C10—C9—H9A	118.5
C3—C2—H2A	120.5	C11—C10—C9	124.16 (8)
C4—C3—C2	119.28 (7)	C11—C10—H10A	117.9
C4—C3—C6	120.83 (7)	C9—C10—H10A	117.9
C2—C3—C6	119.89 (8)	C10—C11—C12	124.50 (8)
C3—C4—C5	120.38 (7)	C10—C11—H11A	117.7
C3—C4—H4A	119.8	C12—C11—H11A	117.7
C5—C4—H4A	119.8	C11—C12—H12A	109.5
N2—C5—N1	118.80 (6)	C11—C12—H12B	109.5
N2—C5—C4	122.84 (7)	H12A—C12—H12B	109.5
N1—C5—C4	118.35 (7)	C11—C12—H12C	109.5
C3—C6—H6A	109.5	H12A—C12—H12C	109.5
C3—C6—H6B	109.5	H12B—C12—H12C	109.5
H6A—C6—H6B	109.5	H1W1—O1W—H2W1	102.7 (17)
C3—C6—H6C	109.5	H1W2—O2W—H2W2	102.4 (15)
C5—N1—C1—C2	0.83 (12)	C3—C4—C5—N2	−179.36 (8)
N1—C1—C2—C3	0.02 (13)	C3—C4—C5—N1	0.62 (11)
C1—C2—C3—C4	−0.51 (13)	O2—C7—C8—C9	13.47 (12)
C1—C2—C3—C6	180.00 (8)	O1—C7—C8—C9	−165.81 (8)
C2—C3—C4—C5	0.19 (12)	C7—C8—C9—C10	175.41 (7)
C6—C3—C4—C5	179.67 (7)	C8—C9—C10—C11	−173.75 (8)
C1—N1—C5—N2	178.84 (8)	C9—C10—C11—C12	177.89 (8)
C1—N1—C5—C4	−1.14 (11)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N1···O2^i	0.97 (2)	1.72 (2)	2.6875 (9)	175 (1)
N2—H1N2···O1^i	0.91 (2)	2.01 (2)	2.9139 (10)	173 (1)
N2—H2N2···O1W	0.94 (2)	1.92 (2)	2.8453 (11)	166 (1)
O2W—H1W2···O2^ii	0.85 (2)	1.91 (2)	2.7510 (10)	167 (2)
O2W—H2W2···O1	0.87 (2)	1.96 (2)	2.8140 (9)	168 (2)
O1W—H1W1···O1^iii	0.84 (2)	2.05 (2)	2.8777 (10)	168 (2)
O1W—H2W1···O2W	0.86 (2)	1.88 (2)	2.7425 (11)	173 (2)

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