2,3-Diamino­pyridinium sorbate–sorbic acid (1/1)

In the title mol­ecular salt–adduct, C₅H₈N₃⁺·C₆H₇O₂⁻·C₆H₈O₂, the 2,3-diamino­pyridinium cation is essentially planar, with a maximum deviation of 0.013 (2) Å, and is protanated at its pyridine N atom. The sorbate anion and sorbic acid mol­ecules exist in extended conformations. In the crystal, the protonated N atom and one of the two amino-group H atoms are hydrogen bonded to the sorbate anion through a pair of N—H...O hydrogen bonds, forming an R₁²(6) ring motif. The carboxyl groups of the sorbic acid mol­ecules and the carboxyl­ate groups of the sorbate anions are connected via O—H...O hydrogen bonds. Furthermore, the ion pairs and neutral mol­ecules are connected via inter­molecular N—H...O hydrogen bonds, forming sheets lying parallel to (100).

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.047
• wR factor = 0.152
• Data-to-parameter ratio = 22.4

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT230_ALERT_2_B Hirshfeld Test Diff for    O1B    --  C6B     ..        8.5 su

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
PLAT042_ALERT_1_C Calc. and Reported MoietyFormula Strings  Differ          ?
PLAT230_ALERT_2_C Hirshfeld Test Diff for    N3     --  C2      ..        5.5 su
PLAT309_ALERT_2_C Single Bonded Oxygen (C-O .GT. 1.3 Ang) ........        O1B
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          1
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600         38

Alert level G
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........         11

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

   1 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
   1 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

Aminopyridines have recently become the focus of extensive studies, mainly because of their wide use as building blocks for synthetic transformations (Peng et al., 2001; Leung et al., 2002). Carboxylic acids are important in crystal engineering due to their strong and directional O—H···O and N—H···O hydrogen bonds; this is the main hydrogen-bonding motif often encountered in carboxylic acid–amine complexes (Banerjee & Murugavel, 2004; Lautie & Belabbes, 1996). Here, we report the synthesis and crystal structure of the title compound, (I).

The asymmetric unit of the title compound, (Fig 1), contains one 2,3-diaminopyridinium cation, one sorbate anion and one neutral sorbic acid molecule. The 2,3-diaminopyridinium cation is planar with a maximum deviation of 0.013 (2) Å for atom C2. Protonation of atom N1 has resulted in a slight increase in the angle C1—N1—C5 [123.71 (17)°]. The sorbate anion and sorbic acid moiety is in the EE configuration. The structure is significantly different chemically and structurally from that of the previously reported 2,3-diaminopyridinium (2E,4E)-hexa-2,4- dienoate compound C₅H₈N₃⁺, C₆H₇O₂^- (Hemamalini & Fun, 2010), even though the same synthesis was used.

In the crystal, (Fig. 2), the protonated N1 atom and the 2-amino group N atom (N2) is hydrogen-bonded to the carboxylate oxygen atoms (O1A and O2A) via a pair of N—H···O hydrogen bonds forming a ring motif R¹₂(6) (Bernstein et al., 1995). The carboxyl groups of the sorbic acid molecules and the carboxylate groups of the sorbate anions are connected via O—H···O hydrogen bonds. Furthermore, the ion pairs and neutral molecules are connected via N—H···O hydrogen bonds (see Table 1 for symmetry codes) forming two-dimensional networks parallel to (100).

Related literature

For a different crystal structure arising from the same synthesis conditions, see: Hemamalini & Fun (2010). For background to aminopyridines, see: Peng et al. (2001); Leung et al. (2002); Banerjee & Murugavel (2004); Lautie & Belabbes (1996). For hydrogen-bond motifs, see: Bernstein et al. (1995). 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 2,3-diaminopyridine (59 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 brown plates of the title compound appeared after a few days.

S3. Refinement

Atoms H1N1, H1N2, H2N2, H1N3 and H2N3 were located from a difference Fourier maps and refined freely [N–H = 0.83 (2)–0.92 (2) Å]. The remaining H atoms were positioned geometrically [C–H = 0.93–0.96 Å and O–H = 0.82 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.

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, showing 50% probability displacement ellipsoids.
	Fig. 2. The crystal packing of title compound (I).

2,3-Diaminopyridinium hexa-2,4-dienoate–hexa-2,4-dienoic acid (1/1)

Crystal data

C5H8N3^+·C6H7O2^−·C6H8O2	F(000) = 712
Mr = 333.38	Dx = 1.214 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4699 reflections
a = 16.1636 (17) Å	θ = 2.5–23.6°
b = 9.6538 (10) Å	µ = 0.09 mm^−1
c = 12.6887 (13) Å	T = 100 K
β = 112.844 (2)°	Plate, brown
V = 1824.6 (3) Å^3	0.47 × 0.25 × 0.06 mm
Z = 4

Data collection

Bruker APEXII DUO CCD diffractometer	5345 independent reflections
Radiation source: fine-focus sealed tube	2898 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.045
ϕ and ω scans	θmax = 30.1°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −22→22
Tmin = 0.960, Tmax = 0.994	k = −13→13
27805 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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.152	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0631P)^2 + 0.2243P] where P = (Fo^2 + 2Fc^2)/3
5345 reflections	(Δ/σ)max < 0.001
239 parameters	Δρmax = 0.30 e Å^−3
0 restraints	Δρmin = −0.22 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 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
N1	0.52439 (11)	0.20084 (17)	0.03419 (12)	0.0703 (4)
N2	0.45891 (11)	0.1854 (2)	0.16546 (18)	0.0778 (5)
N3	0.59685 (10)	0.00896 (17)	0.29774 (14)	0.0713 (4)
C1	0.52362 (10)	0.14816 (17)	0.13081 (13)	0.0563 (4)
C2	0.59314 (9)	0.05457 (16)	0.19419 (13)	0.0522 (4)
C3	0.65504 (10)	0.02052 (18)	0.14930 (15)	0.0642 (4)
H3A	0.7001	−0.0427	0.1878	0.077*
C4	0.65219 (12)	0.0785 (2)	0.04688 (16)	0.0771 (5)
H4A	0.6950	0.0548	0.0179	0.093*
C5	0.58688 (14)	0.1688 (2)	−0.00887 (16)	0.0808 (5)
H5A	0.5844	0.2092	−0.0766	0.097*
O1B	0.20615 (8)	0.22997 (14)	0.43760 (10)	0.0701 (3)
O2B	0.26440 (7)	0.21636 (13)	0.62722 (10)	0.0698 (3)
C6B	0.20207 (10)	0.24501 (15)	0.53806 (14)	0.0541 (4)
C7B	0.11588 (10)	0.29993 (16)	0.53419 (14)	0.0560 (4)
H7BA	0.0703	0.3165	0.4631	0.067*
C8B	0.10027 (10)	0.32670 (15)	0.62678 (13)	0.0536 (4)
H8BA	0.1460	0.3066	0.6969	0.064*
C9B	0.01845 (10)	0.38450 (16)	0.62879 (14)	0.0569 (4)
H9BA	−0.0277	0.4038	0.5588	0.068*
C10B	0.00417 (13)	0.41200 (19)	0.72185 (16)	0.0688 (5)
H10A	0.0505	0.3925	0.7916	0.083*
C11B	−0.07969 (15)	0.4715 (3)	0.7250 (2)	0.0929 (7)
H11A	−0.1059	0.4066	0.7604	0.139*
H11B	−0.1213	0.4904	0.6485	0.139*
H11C	−0.0660	0.5560	0.7683	0.139*
O1A	0.35766 (7)	0.14675 (14)	0.44960 (11)	0.0747 (4)
H1A	0.3058	0.1418	0.4452	0.112*
O2A	0.43810 (7)	0.06465 (17)	0.35977 (11)	0.0830 (4)
C6A	0.36773 (10)	0.06657 (18)	0.37630 (13)	0.0588 (4)
C7A	0.29051 (10)	−0.02288 (17)	0.31033 (13)	0.0571 (4)
H7AA	0.2396	−0.0174	0.3273	0.068*
C8A	0.28871 (10)	−0.10933 (17)	0.22971 (13)	0.0571 (4)
H8AA	0.3407	−0.1171	0.2153	0.069*
C9A	0.21322 (11)	−0.19332 (17)	0.16161 (14)	0.0592 (4)
H9AA	0.1603	−0.1820	0.1733	0.071*
C10A	0.21248 (13)	−0.28488 (19)	0.08416 (16)	0.0716 (5)
H10B	0.2656	−0.2947	0.0726	0.086*
C11A	0.13681 (15)	−0.3735 (2)	0.01381 (18)	0.0891 (6)
H11G	0.1245	−0.3584	−0.0657	0.134*
H11D	0.0846	−0.3507	0.0288	0.134*
H11E	0.1521	−0.4690	0.0325	0.134*
H1N1	0.4814 (17)	0.260 (3)	−0.006 (2)	0.112 (8)*
H1N2	0.4194 (16)	0.234 (2)	0.1193 (19)	0.093 (7)*
H2N2	0.4547 (15)	0.148 (3)	0.225 (2)	0.098 (9)*
H1N3	0.5524 (13)	0.0094 (18)	0.3168 (15)	0.066 (5)*
H2N3	0.6417 (15)	−0.055 (3)	0.3295 (19)	0.104 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0674 (9)	0.0770 (10)	0.0511 (8)	0.0190 (8)	0.0062 (7)	0.0022 (7)
N2	0.0622 (9)	0.0905 (12)	0.0739 (11)	0.0316 (9)	0.0190 (8)	−0.0020 (10)
N3	0.0521 (8)	0.0816 (11)	0.0848 (11)	0.0154 (8)	0.0314 (8)	0.0260 (9)
C1	0.0475 (8)	0.0591 (9)	0.0528 (9)	0.0076 (7)	0.0093 (6)	−0.0078 (7)
C2	0.0435 (7)	0.0516 (8)	0.0558 (9)	0.0029 (6)	0.0132 (6)	0.0003 (7)
C3	0.0476 (8)	0.0699 (10)	0.0708 (11)	0.0105 (7)	0.0181 (7)	−0.0003 (9)
C4	0.0663 (11)	0.1024 (15)	0.0656 (11)	0.0092 (10)	0.0288 (9)	−0.0031 (11)
C5	0.0818 (13)	0.1025 (15)	0.0527 (10)	0.0082 (11)	0.0203 (9)	0.0028 (10)
O1B	0.0584 (7)	0.0927 (9)	0.0518 (6)	0.0105 (6)	0.0133 (5)	−0.0043 (6)
O2B	0.0546 (6)	0.0833 (8)	0.0586 (7)	0.0206 (6)	0.0077 (5)	0.0004 (6)
C6B	0.0472 (8)	0.0474 (8)	0.0572 (9)	0.0013 (6)	0.0087 (7)	−0.0020 (7)
C7B	0.0465 (8)	0.0593 (9)	0.0530 (9)	0.0042 (7)	0.0091 (6)	0.0043 (7)
C8B	0.0484 (8)	0.0488 (8)	0.0542 (9)	0.0001 (6)	0.0097 (6)	0.0031 (7)
C9B	0.0530 (8)	0.0559 (9)	0.0571 (9)	0.0014 (7)	0.0163 (7)	0.0059 (7)
C10B	0.0731 (11)	0.0684 (11)	0.0661 (11)	0.0056 (9)	0.0283 (9)	0.0067 (9)
C11B	0.0984 (15)	0.0950 (15)	0.1081 (17)	0.0154 (12)	0.0648 (13)	0.0127 (13)
O1A	0.0507 (6)	0.0923 (9)	0.0765 (8)	−0.0053 (6)	0.0195 (6)	−0.0293 (7)
O2A	0.0473 (6)	0.1230 (11)	0.0829 (9)	−0.0019 (7)	0.0299 (6)	−0.0065 (8)
C6A	0.0473 (8)	0.0721 (10)	0.0563 (9)	0.0017 (7)	0.0194 (7)	−0.0026 (8)
C7A	0.0488 (8)	0.0681 (10)	0.0578 (9)	0.0007 (7)	0.0245 (7)	−0.0049 (8)
C8A	0.0536 (8)	0.0649 (9)	0.0525 (8)	0.0105 (7)	0.0201 (7)	0.0031 (7)
C9A	0.0641 (10)	0.0571 (9)	0.0553 (9)	0.0064 (7)	0.0218 (7)	−0.0006 (7)
C10A	0.0771 (12)	0.0684 (11)	0.0646 (10)	0.0135 (9)	0.0222 (9)	−0.0041 (9)
C11A	0.1050 (16)	0.0634 (11)	0.0814 (14)	0.0037 (11)	0.0172 (12)	−0.0159 (10)

Geometric parameters (Å, º)

N1—C1	1.332 (2)	C9B—C10B	1.315 (2)
N1—C5	1.358 (2)	C9B—H9BA	0.9300
N1—H1N1	0.89 (3)	C10B—C11B	1.487 (3)
N2—C1	1.332 (2)	C10B—H10A	0.9300
N2—H1N2	0.83 (2)	C11B—H11A	0.9600
N2—H2N2	0.86 (2)	C11B—H11B	0.9600
N3—C2	1.365 (2)	C11B—H11C	0.9600
N3—H1N3	0.843 (18)	O1A—C6A	1.2682 (19)
N3—H2N3	0.92 (2)	O1A—H1A	0.8200
C1—C2	1.423 (2)	O2A—C6A	1.2341 (18)
C2—C3	1.370 (2)	C6A—C7A	1.481 (2)
C3—C4	1.399 (3)	C7A—C8A	1.312 (2)
C3—H3A	0.9300	C7A—H7AA	0.9300
C4—C5	1.339 (3)	C8A—C9A	1.440 (2)
C4—H4A	0.9300	C8A—H8AA	0.9300
C5—H5A	0.9300	C9A—C10A	1.318 (2)
O1B—C6B	1.310 (2)	C9A—H9AA	0.9300
O2B—C6B	1.2192 (17)	C10A—C11A	1.475 (3)
C6B—C7B	1.474 (2)	C10A—H10B	0.9300
C7B—C8B	1.319 (2)	C11A—H11G	0.9600
C7B—H7BA	0.9300	C11A—H11D	0.9600
C8B—C9B	1.445 (2)	C11A—H11E	0.9600
C8B—H8BA	0.9300
C1—N1—C5	123.90 (16)	C10B—C9B—H9BA	117.5
C1—N1—H1N1	119.1 (16)	C8B—C9B—H9BA	117.5
C5—N1—H1N1	117.0 (16)	C9B—C10B—C11B	125.59 (18)
C1—N2—H1N2	114.2 (15)	C9B—C10B—H10A	117.2
C1—N2—H2N2	120.9 (16)	C11B—C10B—H10A	117.2
H1N2—N2—H2N2	124 (2)	C10B—C11B—H11A	109.5
C2—N3—H1N3	123.5 (12)	C10B—C11B—H11B	109.5
C2—N3—H2N3	111.8 (14)	H11A—C11B—H11B	109.5
H1N3—N3—H2N3	119.6 (19)	C10B—C11B—H11C	109.5
N2—C1—N1	119.33 (16)	H11A—C11B—H11C	109.5
N2—C1—C2	122.29 (17)	H11B—C11B—H11C	109.5
N1—C1—C2	118.38 (15)	C6A—O1A—H1A	109.5
N3—C2—C3	123.83 (15)	O2A—C6A—O1A	121.53 (16)
N3—C2—C1	118.61 (14)	O2A—C6A—C7A	121.69 (15)
C3—C2—C1	117.49 (15)	O1A—C6A—C7A	116.77 (13)
C2—C3—C4	121.61 (16)	C8A—C7A—C6A	124.78 (14)
C2—C3—H3A	119.2	C8A—C7A—H7AA	117.6
C4—C3—H3A	119.2	C6A—C7A—H7AA	117.6
C5—C4—C3	119.07 (17)	C7A—C8A—C9A	125.68 (15)
C5—C4—H4A	120.5	C7A—C8A—H8AA	117.2
C3—C4—H4A	120.5	C9A—C8A—H8AA	117.2
C4—C5—N1	119.52 (19)	C10A—C9A—C8A	125.81 (17)
C4—C5—H5A	120.2	C10A—C9A—H9AA	117.1
N1—C5—H5A	120.2	C8A—C9A—H9AA	117.1
O2B—C6B—O1B	122.84 (14)	C9A—C10A—C11A	127.25 (19)
O2B—C6B—C7B	122.85 (15)	C9A—C10A—H10B	116.4
O1B—C6B—C7B	114.30 (13)	C11A—C10A—H10B	116.4
C8B—C7B—C6B	123.09 (14)	C10A—C11A—H11G	109.5
C8B—C7B—H7BA	118.5	C10A—C11A—H11D	109.5
C6B—C7B—H7BA	118.5	H11G—C11A—H11D	109.5
C7B—C8B—C9B	125.75 (14)	C10A—C11A—H11E	109.5
C7B—C8B—H8BA	117.1	H11G—C11A—H11E	109.5
C9B—C8B—H8BA	117.1	H11D—C11A—H11E	109.5
C10B—C9B—C8B	125.09 (16)
C5—N1—C1—N2	−179.49 (19)	O2B—C6B—C7B—C8B	2.3 (2)
C5—N1—C1—C2	1.2 (3)	O1B—C6B—C7B—C8B	−177.53 (15)
N2—C1—C2—N3	−4.5 (3)	C6B—C7B—C8B—C9B	177.96 (14)
N1—C1—C2—N3	174.80 (15)	C7B—C8B—C9B—C10B	−179.26 (17)
N2—C1—C2—C3	178.37 (17)	C8B—C9B—C10B—C11B	179.96 (18)
N1—C1—C2—C3	−2.3 (2)	O2A—C6A—C7A—C8A	−0.6 (3)
N3—C2—C3—C4	−174.93 (17)	O1A—C6A—C7A—C8A	178.42 (16)
C1—C2—C3—C4	2.0 (2)	C6A—C7A—C8A—C9A	−177.50 (15)
C2—C3—C4—C5	−0.5 (3)	C7A—C8A—C9A—C10A	−176.71 (18)
C3—C4—C5—N1	−0.8 (3)	C8A—C9A—C10A—C11A	179.34 (18)
C1—N1—C5—C4	0.4 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1A—H1A···O1B	0.82	1.79	2.5252 (19)	148
N1—H1N1···O1A^i	0.89 (3)	2.06 (3)	2.887 (2)	153 (3)
N1—H1N1···O2A^i	0.89 (3)	2.31 (3)	3.094 (2)	147 (2)
N2—H1N2···O1A^i	0.83 (2)	2.30 (2)	3.054 (2)	152 (2)
N2—H1N2···O2B^i	0.83 (2)	2.59 (3)	3.136 (2)	125 (2)
N2—H2N2···O2A	0.86 (2)	2.00 (3)	2.863 (2)	177 (2)
N3—H1N3···O2A	0.84 (2)	2.19 (2)	3.010 (2)	166.1 (16)
N3—H2N3···O2B^ii	0.92 (3)	2.09 (3)	3.002 (2)	170 (2)

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