2,6-Diamino­pyridinium 2-carb­oxy­benzoate

In the crystal of the title mol­ecular salt, C₅H₈N₃⁺·C₈H₅O₄⁻, the diamino­pyridine cation and the phthalate anion are linked by a pair of N—H...O hydrogen bonds. Within the phthalate anion, an almost symmetrical O—H...O hydrogen bond is observed. The ion pairs are linked by further N—H...O hydrogen bonds, generating a two-dimensional network lying parallel to (10).

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.053
• wR factor = 0.197
• Data-to-parameter ratio = 15.2

checkCIF/PLATON results

No syntax errors found



Alert level C
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         31
PLAT042_ALERT_1_C Calc. and Reported MoietyFormula Strings  Differ          ?
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          2

Alert level G
PLAT072_ALERT_2_G SHELXL First Parameter in WGHT Unusually Large.       0.11
PLAT960_ALERT_3_G Number of Intensities with I .LT. - 2*sig(I) ..           2
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........          1

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

   1 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
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Phthalic acid is an aromatic dicarboxylic acid which can be used for the preparation of many organic and inorganic compounds such as dyes, perfumes and phthalates(Brike et al. 2002). Some of its derivatives have anti-tumor promoting action (Yamamoto et al. 1990). The diaminopyridine have an important role in the preparation of aromatic azo dyes (Abu Zuhri & Cox, 1989; Inuzuka & Fujimoto, 1990) and in many polarographic investigations (El-Mossalamy, 2001).

All geometrical parameters in the title compound, C₅H₈N₃⁺.C₈H₅O₄^-,(I), are within normal ranges and are comparable with the related structures (Büyükgüngör & Odabąsoǧlu, 2006; Al-Dajani et al., 2009; Shabari et al., 2010). In the crystal structure, the anion and the cation were linked by N1—H1A···O3 and N2—H2A···O4 interactions. In the phthalate anion, a strong intramolecular interaction of O2—H1O2···O3 was observed. Intermolecular N—H···O hydrogen bonds (Table 1) further contribute to the stabilization of crystal structure, forming an infinite two-dimensional network parallel to the (101) plane.

Related literature

For background to 2,6-diaminopyridines, see: Abu Zuhri & Cox (1989); Inuzuka & Fujimoto (1990); El-Mossalamy (2001). For background and the biological activity of phthalic acid, see: Brike et al. (2002); Yamamoto et al. (1990). For related structures: see: Büyükgüngör & Odabąsoğlu (2006); Al-Dajani et al. (2009); Shabari et al. (2010). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).

S2. Experimental

In a round bottom flask, 25ml of THF was mixed with 2,6-diaminopyridine (0.01 mol, 1.1 g) with stirring. Phthalic anhydrate (0.01 mol, 1.5 g) was dissolved in THF and then added in small portions into the round bottom flask and refluxed for 2 hours. The gray precipitate formed was filtrated and washed with THF. Brown plates of (I) were formed by dissolving the precipitate in hot water and letting it to cool at room temperature. The crystals was then filtered and dried at 60°C.

S3. Refinement

O-bound H atoms were located from a difference Fourier map and refined as riding with U_iso(H) = 1.5U_eq(O).The remaining H atoms were positioned geometrically [N–H = 0.86Å, C–H = 0.93 Å and refined using a riding model, with U_iso(H) = 1.2U_eq(N,C)].

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 molecular structure of (I), showing 50% probability displacement ellipsoids. Hydrogen atoms are shown as spheres of arbitrary radius. Dashed lines indicate the intermolecular hydrogen bonds.
	Fig. 2. The crystal packing of (I) viewed down the b axis. Dashed lines indicate hydrogen bonds. H atoms not involved in the hydrogen bond interactions have been omitted for clarity.

2,6-Diaminopyridinium 2-carboxybenzoate

Crystal data

C5H8N3^+·C8H5O4^−	F(000) = 1152
Mr = 275.26	Dx = 1.498 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 975 reflections
a = 32.332 (11) Å	θ = 3.8–28.1°
b = 3.7246 (14) Å	µ = 0.11 mm^−1
c = 24.184 (8) Å	T = 100 K
β = 123.036 (6)°	Plate, brown
V = 2441.5 (15) Å^3	0.47 × 0.10 × 0.03 mm
Z = 8

Data collection

Bruker APEXII DUO CCD area-detector diffractometer	2757 independent reflections
Radiation source: fine-focus sealed tube	1869 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.041
φ and ω scans	θmax = 27.5°, θmin = 3.4°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −36→42
Tmin = 0.948, Tmax = 0.996	k = −4→4
5492 measured reflections	l = −31→27

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)] = 0.053	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.197	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.1138P)^2] where P = (Fo^2 + 2Fc^2)/3
2757 reflections	(Δ/σ)max < 0.001
181 parameters	Δρmax = 0.41 e Å^−3
0 restraints	Δρmin = −0.40 e Å^−3

Special details

Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems 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	0.09892 (7)	0.9810 (6)	0.16036 (9)	0.0153 (5)
H1A	0.1109	0.8974	0.1388	0.018*
N2	0.02334 (7)	0.8089 (7)	0.07262 (10)	0.0195 (5)
H2A	0.0381	0.7329	0.0542	0.023*
H2B	−0.0082	0.7882	0.0526	0.023*
N3	0.17839 (7)	1.1355 (7)	0.24299 (10)	0.0210 (5)
H3A	0.1883	1.0487	0.2192	0.025*
H3B	0.1993	1.2268	0.2810	0.025*
C1	0.04920 (8)	0.9585 (7)	0.13210 (11)	0.0158 (5)
C2	0.02953 (9)	1.0896 (8)	0.16702 (11)	0.0179 (6)
H2C	−0.0042	1.0754	0.1494	0.021*
C3	0.06092 (9)	1.2402 (8)	0.22794 (12)	0.0191 (6)
H3C	0.0478	1.3309	0.2510	0.023*
C4	0.11140 (9)	1.2624 (8)	0.25640 (11)	0.0169 (5)
H4A	0.1319	1.3636	0.2980	0.020*
C5	0.13083 (8)	1.1287 (7)	0.22106 (11)	0.0153 (5)
O1	0.26121 (6)	−0.0595 (6)	0.12827 (8)	0.0228 (5)
O2	0.21888 (6)	0.2628 (6)	0.15685 (7)	0.0191 (4)
H1O2	0.1816	0.4181	0.1225	0.029*
O3	0.14264 (6)	0.6094 (5)	0.10279 (8)	0.0193 (5)
O4	0.06986 (6)	0.5317 (6)	0.01065 (9)	0.0272 (5)
C6	0.18695 (8)	0.1875 (7)	0.03925 (11)	0.0148 (5)
C7	0.20221 (9)	0.0642 (8)	−0.00144 (12)	0.0170 (5)
H7A	0.2336	−0.0336	0.0179	0.020*
C8	0.17220 (9)	0.0825 (8)	−0.06960 (12)	0.0193 (6)
H8A	0.1836	0.0045	−0.0955	0.023*
C9	0.12537 (9)	0.2173 (8)	−0.09827 (11)	0.0195 (6)
H9A	0.1045	0.2259	−0.1440	0.023*
C10	0.10903 (9)	0.3408 (7)	−0.05943 (11)	0.0159 (5)
H10A	0.0772	0.4316	−0.0797	0.019*
C11	0.13903 (8)	0.3330 (7)	0.00959 (11)	0.0145 (5)
C12	0.11507 (8)	0.4977 (7)	0.04302 (11)	0.0161 (5)
C13	0.22537 (8)	0.1262 (7)	0.11219 (11)	0.0154 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0160 (10)	0.0203 (12)	0.0105 (9)	0.0010 (9)	0.0079 (8)	−0.0016 (9)
N2	0.0140 (9)	0.0278 (13)	0.0146 (9)	−0.0007 (10)	0.0066 (8)	−0.0046 (10)
N3	0.0140 (9)	0.0340 (15)	0.0135 (9)	−0.0008 (10)	0.0064 (8)	−0.0042 (10)
C1	0.0162 (11)	0.0156 (13)	0.0147 (10)	0.0007 (10)	0.0079 (9)	0.0025 (10)
C2	0.0162 (11)	0.0185 (14)	0.0181 (11)	0.0005 (11)	0.0089 (10)	0.0018 (11)
C3	0.0236 (12)	0.0207 (14)	0.0175 (11)	0.0051 (12)	0.0141 (10)	0.0020 (11)
C4	0.0196 (11)	0.0175 (13)	0.0136 (11)	−0.0001 (11)	0.0091 (10)	−0.0004 (11)
C5	0.0170 (11)	0.0148 (13)	0.0111 (10)	−0.0031 (10)	0.0057 (9)	−0.0006 (10)
O1	0.0190 (9)	0.0286 (11)	0.0184 (8)	0.0056 (9)	0.0085 (7)	0.0023 (9)
O2	0.0170 (8)	0.0274 (11)	0.0127 (8)	0.0010 (8)	0.0078 (7)	−0.0007 (8)
O3	0.0155 (8)	0.0272 (11)	0.0151 (8)	0.0011 (8)	0.0084 (7)	−0.0045 (8)
O4	0.0152 (9)	0.0409 (13)	0.0235 (9)	−0.0007 (9)	0.0092 (7)	−0.0105 (10)
C6	0.0147 (10)	0.0162 (13)	0.0134 (10)	−0.0004 (10)	0.0076 (9)	0.0005 (10)
C7	0.0161 (11)	0.0185 (13)	0.0184 (11)	−0.0018 (11)	0.0107 (9)	−0.0010 (11)
C8	0.0261 (13)	0.0192 (14)	0.0191 (11)	−0.0028 (12)	0.0166 (10)	−0.0008 (11)
C9	0.0209 (12)	0.0205 (14)	0.0126 (10)	−0.0037 (11)	0.0062 (9)	−0.0003 (11)
C10	0.0141 (10)	0.0156 (13)	0.0162 (11)	−0.0024 (10)	0.0072 (9)	−0.0013 (10)
C11	0.0153 (10)	0.0127 (12)	0.0162 (11)	−0.0016 (10)	0.0090 (9)	−0.0017 (10)
C12	0.0159 (11)	0.0176 (14)	0.0161 (11)	−0.0023 (11)	0.0095 (9)	−0.0015 (11)
C13	0.0141 (10)	0.0166 (13)	0.0161 (11)	−0.0004 (10)	0.0086 (9)	0.0020 (10)

Geometric parameters (Å, º)

N1—C1	1.364 (3)	O2—C13	1.310 (3)
N1—C5	1.368 (3)	O2—H1O2	1.1764
N1—H1A	0.8600	O3—C12	1.285 (3)
N2—C1	1.329 (3)	O3—H1O2	1.2919
N2—H2A	0.8600	O4—C12	1.232 (3)
N2—H2B	0.8600	C6—C7	1.397 (3)
N3—C5	1.326 (3)	C6—C11	1.413 (3)
N3—H3A	0.8600	C6—C13	1.522 (3)
N3—H3B	0.8600	C7—C8	1.385 (3)
C1—C2	1.393 (3)	C7—H7A	0.9300
C2—C3	1.373 (3)	C8—C9	1.372 (3)
C2—H2C	0.9300	C8—H8A	0.9300
C3—C4	1.386 (3)	C9—C10	1.383 (3)
C3—H3C	0.9300	C9—H9A	0.9300
C4—C5	1.399 (3)	C10—C11	1.401 (3)
C4—H4A	0.9300	C10—H10A	0.9300
O1—C13	1.217 (3)	C11—C12	1.521 (3)
C1—N1—C5	123.8 (2)	C12—O3—H1O2	100.1
C1—N1—H1A	118.1	C7—C6—C11	118.6 (2)
C5—N1—H1A	118.1	C7—C6—C13	112.8 (2)
C1—N2—H2A	120.0	C11—C6—C13	128.5 (2)
C1—N2—H2B	120.0	C8—C7—C6	122.3 (2)
H2A—N2—H2B	120.0	C8—C7—H7A	118.8
C5—N3—H3A	120.0	C6—C7—H7A	118.8
C5—N3—H3B	120.0	C9—C8—C7	118.9 (2)
H3A—N3—H3B	120.0	C9—C8—H8A	120.5
N2—C1—N1	116.2 (2)	C7—C8—H8A	120.5
N2—C1—C2	125.2 (2)	C8—C9—C10	120.2 (2)
N1—C1—C2	118.5 (2)	C8—C9—H9A	119.9
C3—C2—C1	118.6 (2)	C10—C9—H9A	119.9
C3—C2—H2C	120.7	C9—C10—C11	122.0 (2)
C1—C2—H2C	120.7	C9—C10—H10A	119.0
C2—C3—C4	122.6 (2)	C11—C10—H10A	119.0
C2—C3—H3C	118.7	C10—C11—C6	117.9 (2)
C4—C3—H3C	118.7	C10—C11—C12	113.7 (2)
C3—C4—C5	118.3 (2)	C6—C11—C12	128.3 (2)
C3—C4—H4A	120.8	O4—C12—O3	122.4 (2)
C5—C4—H4A	120.8	O4—C12—C11	118.4 (2)
N3—C5—N1	118.0 (2)	O3—C12—C11	119.1 (2)
N3—C5—C4	123.9 (2)	O1—C13—O2	120.6 (2)
N1—C5—C4	118.1 (2)	O1—C13—C6	119.3 (2)
C13—O2—H1O2	99.9	O2—C13—C6	120.0 (2)
C5—N1—C1—N2	179.6 (2)	C9—C10—C11—C6	−1.2 (4)
C5—N1—C1—C2	−0.7 (4)	C9—C10—C11—C12	177.1 (2)
N2—C1—C2—C3	−179.5 (3)	C7—C6—C11—C10	0.9 (4)
N1—C1—C2—C3	0.9 (4)	C13—C6—C11—C10	−175.8 (2)
C1—C2—C3—C4	−0.9 (4)	C7—C6—C11—C12	−177.1 (3)
C2—C3—C4—C5	0.7 (4)	C13—C6—C11—C12	6.2 (4)
C1—N1—C5—N3	−179.8 (2)	C10—C11—C12—O4	19.0 (4)
C1—N1—C5—C4	0.5 (4)	C6—C11—C12—O4	−162.9 (3)
C3—C4—C5—N3	179.8 (3)	C10—C11—C12—O3	−158.2 (2)
C3—C4—C5—N1	−0.4 (4)	C6—C11—C12—O3	19.9 (4)
C11—C6—C7—C8	0.5 (4)	C7—C6—C13—O1	−9.9 (3)
C13—C6—C7—C8	177.8 (3)	C11—C6—C13—O1	167.0 (3)
C6—C7—C8—C9	−1.8 (4)	C7—C6—C13—O2	172.4 (2)
C7—C8—C9—C10	1.6 (4)	C11—C6—C13—O2	−10.8 (4)
C8—C9—C10—C11	−0.1 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H1O2···O3	1.18	1.29	2.437 (3)	162
N1—H1A···O3	0.86	1.98	2.828 (3)	167
N2—H2A···O4	0.86	1.98	2.834 (3)	177
N2—H2B···O4^i	0.86	2.10	2.851 (3)	145
N3—H3A···O2^ii	0.86	2.35	3.042 (3)	138
N3—H3B···O1^iii	0.86	2.01	2.858 (3)	171

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