Ethyl­enedi­ammonium 4-nitro­anthranilate dihydrate

The crystal structure of ethyl­enedi­ammonium 4-nitro­anthranilate dihydrate, [(C₂H₁₀N₂)²⁺·2(C₇H₅N₂O₄)^-·2(H₂O)], shows a three-dimensional hydrogen-bonded polymer in which both of the amine groups of ethyl­enedi­amine are protonated and each gives a total of four hydrogen-bonded interactions with oxy­gen and amine N atoms of the anthranilate anions as well as with the water mol­ecules. The centrosymmetrically related anthranilate species are also linked directly to the water mol­ecules, and give a double-chain structure down the b axis.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.045
• wR factor = 0.137
• Data-to-parameter ratio = 14.2

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

Ethylenediamine (ethane-1,2-diamine = EN) reacts with acids to give stable crystalline salts and because of the relative closeness of the dissociation constants of EN (pK_a1 = 7.3; pK_a2 = 10.1), both amine groups are protonated even in reactions with weak organic acids. With the EN²⁺ species, as is the case with protonated primary amine groups, the —NH₃⁺ protons may be involved in up to six intermolecular hydrogen-bonding interactions with suitable acceptor atoms. The resulting hydrogen-bonded polymer structures acquire considerable crystal stability together with enhanced melting points. This is seen with the EN salts of the relatively strong nitro-substituted benzoic acids, e.g. 3,5-dinitrobenzoic acid (DNBA), [(EN)²⁺ 2(DNBA)⁻] (Nethaji et al., 1992; Lynch et al., 1994), while crystallization often includes lattice water molecules, increasing the structure-making e.g. ethylenediammonium 5-nitrosalicylate hydrate, [(EN)²⁺ 2(5-NSA)⁺. H₂O] (Smith & Hartono, 2002). With the bifunctional 3,5-dinitrosalicylic acid (DNSA), the rare occurrence of the (DNSA)²⁻ species has been observed in the salt [(EN)²⁺ (DNSA)²⁻] (Smith et al., 2002). Our interest lies in the characterization of the hydrogen-bonding interactions of the nitro-substituted aromatic acids with Lewis bases and the structure of the title compound from the reaction of 4-nitroanthranilic acid (4-NAA) with EN, the hydrate, best described in terms of the centrosymmetric molcular unit (the unit-cell contents) [(EN)²⁺ 2(4-NAA)⁻·2(H₂O)], (I), is reported here.

The structure determination of (I) shows that both the primary amine groups of ethylenediamine are protonated (Fig. 1). An intramolecular hydrogen bond is found between an amine-H and an oxygen of the carboxyl group of the 4-NAA anion [N1—H1A···O2; 2.694 (2) Å]. The 4-NAA anions translated one unit along the b cell direction are linked by N1—H1B···O1(x, 1 + y, z) hydrogen bonds to form an infinite one dimensional chain. The molecules in the chain are linked to those in the inversion related chain (1 − x, −y, 1 − z) by the water molecules through O—H···O hydrogen bonds to form a double chain structure (Fig. 2). These 4-NAA anion chains stack down the a cell direction and are linked by the EN cations as well as the water molecules giving a three-dimensional polymer (Fig. 3). A full hydrogen bond listing is given in Table 1.

S2. Experimental

The synthesis of the title compound was carried out by heating under reflux for 10 min, 1 mmol quantities of 4-nitroanthranilic acid (2-amino-4-nitrobenzoic acid = 4-NAA) and ethylenediamine (EN) in 50 ml of 80% ethanol/water. After concentration to ca 30 ml, partial room temperature evaporation of the hot-filtered solution gave red crystals.

S3. Refinement

Hydrogen atoms involved in hydrogen-bonding interactions (H1A, H1B, H3A, H3B, H3C, H5A, H5B) were located from a difference Fourier map and their positional and isotropic thermal parameters were refined. Others were included in the refinement at calculated positions as riding models. For refined hydrogen atoms, the N–H range is 0.87 (2)–0.92 (2) Å; the O–H (water) values are 0.79 (3) and 0.84 (2) Å.

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXTL (Bruker, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: PLATON (Spek, 1999).

Figures

	Fig. 1. Molecular configuration and atom-naming scheme for the individual 4-NAA anion, the EN cation and the water species in (I). Atoms are shown as 40% probability ellipsoids
	Fig. 2. A view of the double chain formation by 4-NAA and water molecules.
	Fig. 3. Packing in the unit cell, viewed down b, showing hydrogen-bonding associations as broken lines.

(I)

Crystal data

C2H10N2^2+·2C7H5N2O4^−·2H2O	Z = 1
Mr = 460.42	F(000) = 242
Triclinic, P1	Dx = 1.524 Mg m^−3
Hall symbol: -P 1	Melting point = 493.6–495.4 K
a = 6.6473 (5) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.0748 (5) Å	Cell parameters from 2947 reflections
c = 11.2317 (8) Å	θ = 3.0–28.3°
α = 76.686 (2)°	µ = 0.13 mm^−1
β = 77.660 (2)°	T = 293 K
γ = 89.525 (2)°	Plate, red
V = 501.67 (6) Å^3	0.40 × 0.30 × 0.20 mm

Data collection

Bruker SMART CCD area detector diffractometer	2052 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.046
Graphite monochromator	θmax = 28.6°, θmin = 1.9°
ϕ and ω scans	h = −8→8
4462 measured reflections	k = −9→9
2475 independent reflections	l = −15→14

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)] = 0.045	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.137	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0745P)^2 + 0.0989P] where P = (Fo^2 + 2Fc^2)/3
2475 reflections	(Δ/σ)max = 0.010
174 parameters	Δρmax = 0.26 e Å^−3
0 restraints	Δρmin = −0.23 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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 > σ(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
C1	0.64571 (17)	−0.04597 (16)	0.15627 (10)	0.0277 (3)
C2	0.66670 (18)	0.15338 (17)	0.15449 (11)	0.0301 (3)
C3	0.7519 (2)	0.28286 (17)	0.03922 (12)	0.0344 (3)
H3	0.7677	0.4149	0.0351	0.041*
C4	0.81153 (19)	0.21337 (19)	−0.06693 (11)	0.0336 (3)
C5	0.79504 (19)	0.0192 (2)	−0.06782 (11)	0.0345 (3)
H5	0.8380	−0.0239	−0.1410	0.041*
C6	0.71171 (18)	−0.10772 (17)	0.04521 (11)	0.0312 (3)
H6	0.6990	−0.2394	0.0475	0.037*
C7	0.54568 (19)	−0.19649 (17)	0.27287 (11)	0.0325 (3)
C8	0.0253 (2)	0.94508 (18)	0.56105 (11)	0.0372 (3)
H8A	0.1297	1.0184	0.5823	0.045*
H8B	−0.0970	0.9292	0.6280	0.045*
N1	0.6138 (2)	0.22588 (18)	0.25992 (11)	0.0425 (3)
N2	0.90109 (19)	0.35319 (19)	−0.18554 (10)	0.0447 (3)
N3	0.1014 (2)	0.75257 (16)	0.54837 (11)	0.0375 (3)
H3A	0.002 (3)	0.682 (3)	0.5334 (17)	0.053 (5)*
H3B	0.133 (3)	0.695 (3)	0.619 (2)	0.062 (5)*
H3C	0.219 (3)	0.763 (2)	0.4869 (17)	0.047 (4)*
O1	0.5325 (2)	−0.36820 (14)	0.26359 (10)	0.0555 (3)
O2	0.47940 (18)	−0.14314 (15)	0.37310 (9)	0.0472 (3)
O3	0.9185 (3)	0.52434 (19)	−0.18427 (12)	0.0736 (5)
O4	0.9547 (2)	0.2929 (2)	−0.28036 (10)	0.0613 (4)
O5	0.27641 (17)	0.39858 (16)	0.46802 (11)	0.0466 (3)
H5A	0.355 (3)	0.470 (3)	0.406 (2)	0.058 (5)*
H1A	0.531 (3)	0.151 (3)	0.3245 (19)	0.054 (5)*
H1B	0.597 (3)	0.343 (3)	0.2492 (17)	0.049 (5)*
H5B	0.348 (4)	0.341 (4)	0.511 (2)	0.076 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0282 (5)	0.0256 (6)	0.0268 (6)	0.0010 (4)	−0.0046 (4)	−0.0023 (4)
C2	0.0330 (6)	0.0280 (6)	0.0276 (6)	0.0008 (4)	−0.0048 (4)	−0.0045 (4)
C3	0.0425 (7)	0.0254 (6)	0.0325 (6)	−0.0030 (5)	−0.0079 (5)	−0.0012 (4)
C4	0.0323 (6)	0.0383 (7)	0.0252 (6)	−0.0042 (5)	−0.0058 (4)	0.0019 (5)
C5	0.0340 (6)	0.0434 (7)	0.0264 (6)	0.0014 (5)	−0.0052 (4)	−0.0103 (5)
C6	0.0329 (6)	0.0282 (6)	0.0327 (6)	0.0018 (4)	−0.0067 (5)	−0.0080 (4)
C7	0.0329 (6)	0.0289 (6)	0.0311 (6)	−0.0020 (4)	−0.0039 (5)	−0.0008 (4)
C8	0.0486 (7)	0.0330 (6)	0.0293 (6)	0.0010 (5)	−0.0055 (5)	−0.0084 (5)
N1	0.0616 (8)	0.0286 (6)	0.0329 (6)	−0.0001 (5)	0.0005 (5)	−0.0084 (4)
N2	0.0452 (7)	0.0520 (7)	0.0299 (6)	−0.0107 (5)	−0.0082 (5)	0.0053 (5)
N3	0.0455 (6)	0.0309 (6)	0.0310 (6)	−0.0003 (5)	−0.0021 (5)	−0.0027 (4)
O1	0.0759 (8)	0.0254 (5)	0.0504 (6)	−0.0053 (5)	0.0106 (5)	−0.0016 (4)
O2	0.0616 (7)	0.0402 (5)	0.0307 (5)	−0.0120 (5)	0.0066 (4)	−0.0049 (4)
O3	0.1121 (12)	0.0524 (7)	0.0433 (7)	−0.0338 (7)	−0.0106 (7)	0.0104 (5)
O4	0.0693 (8)	0.0758 (9)	0.0272 (5)	0.0007 (6)	0.0018 (5)	0.0001 (5)
O5	0.0448 (6)	0.0462 (6)	0.0394 (6)	−0.0088 (5)	−0.0045 (5)	0.0048 (5)

Geometric parameters (Å, º)

C1—C6	1.3975 (16)	C8—N3	1.4758 (17)
C1—C2	1.4135 (16)	C8—C8^i	1.517 (2)
C1—C7	1.5128 (15)	C8—H8A	0.97
C2—N1	1.3740 (16)	C8—H8B	0.97
C2—C3	1.4089 (17)	N1—H1A	0.88 (2)
C3—C4	1.3730 (18)	N1—H1B	0.82 (2)
C3—H3	0.93	N2—O4	1.2195 (17)
C4—C5	1.3812 (19)	N2—O3	1.2210 (18)
C4—N2	1.4736 (15)	N3—H3A	0.90 (2)
C5—C6	1.3812 (18)	N3—H3B	0.87 (2)
C5—H5	0.93	N3—H3C	0.915 (18)
C6—H6	0.93	O5—H5A	0.84 (2)
C7—O1	1.2483 (16)	O5—H5B	0.79 (3)
C7—O2	1.2588 (16)
C6—C1—C2	119.33 (10)	O2—C7—C1	118.94 (11)
C6—C1—C7	117.84 (10)	N3—C8—C8^i	109.84 (13)
C2—C1—C7	122.78 (11)	N3—C8—H8A	109.7
N1—C2—C3	118.54 (11)	C8^i—C8—H8A	109.7
N1—C2—C1	123.30 (11)	N3—C8—H8B	109.7
C3—C2—C1	118.13 (11)	C8^i—C8—H8B	109.7
C4—C3—C2	119.73 (11)	H8A—C8—H8B	108.2
C4—C3—H3	120.1	C2—N1—H1A	115.8 (13)
C2—C3—H3	120.1	C2—N1—H1B	117.0 (12)
C3—C4—C5	123.44 (11)	H1A—N1—H1B	116.3 (18)
C3—C4—N2	118.12 (12)	O4—N2—O3	122.99 (12)
C5—C4—N2	118.43 (12)	O4—N2—C4	118.63 (13)
C4—C5—C6	116.82 (11)	O3—N2—C4	118.38 (12)
C4—C5—H5	121.6	C8—N3—H3A	109.5 (12)
C6—C5—H5	121.6	C8—N3—H3B	107.6 (13)
C5—C6—C1	122.54 (11)	H3A—N3—H3B	109.6 (18)
C5—C6—H6	118.7	C8—N3—H3C	111.5 (11)
C1—C6—H6	118.7	H3A—N3—H3C	111.2 (15)
O1—C7—O2	123.55 (11)	H3B—N3—H3C	107.3 (18)
O1—C7—C1	117.51 (11)	H5A—O5—H5B	107 (2)
C6—C1—C2—N1	−177.28 (11)	C2—C1—C6—C5	−0.87 (19)
C7—C1—C2—N1	5.44 (19)	C7—C1—C6—C5	176.55 (11)
C6—C1—C2—C3	0.76 (18)	C6—C1—C7—O1	1.70 (18)
C7—C1—C2—C3	−176.52 (11)	C2—C1—C7—O1	179.02 (12)
N1—C2—C3—C4	178.14 (11)	C6—C1—C7—O2	−177.87 (11)
C1—C2—C3—C4	0.01 (19)	C2—C1—C7—O2	−0.55 (19)
C2—C3—C4—C5	−0.8 (2)	C3—C4—N2—O4	179.95 (12)
C2—C3—C4—N2	−179.65 (11)	C5—C4—N2—O4	1.00 (19)
C3—C4—C5—C6	0.67 (19)	C3—C4—N2—O3	0.1 (2)
N2—C4—C5—C6	179.56 (11)	C5—C4—N2—O3	−178.89 (13)
C4—C5—C6—C1	0.16 (19)

Symmetry code: (i) −x, −y+2, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O2	0.88 (2)	2.04 (2)	2.6935 (17)	130.8 (18)
N1—H1B···O1^ii	0.82 (2)	2.12 (2)	2.9258 (17)	167.8 (17)
N3—H3A···O5^iii	0.90 (2)	1.95 (2)	2.7960 (18)	157.5 (19)
N3—H3B···O3^iv	0.87 (2)	2.41 (2)	3.0564 (18)	130.9 (17)
N3—H3B···N1^v	0.87 (2)	2.52 (2)	3.1847 (18)	133.8 (18)
N3—H3C···O2^ii	0.917 (19)	1.937 (19)	2.8250 (17)	162.5 (14)
O5—H5A···O1^ii	0.84 (2)	1.91 (2)	2.7429 (16)	179 (2)
O5—H5B···O2^vi	0.79 (3)	2.18 (3)	2.9647 (16)	171 (3)
C6—H6···O1	0.93	2.41	2.7454 (16)	101

Symmetry codes: (ii) x, y+1, z; (iii) −x, −y+1, −z+1; (iv) x−1, y, z+1; (v) −x+1, −y+1, −z+1; (vi) −x+1, −y, −z+1.