Guanidinium 3,5-di­nitro­salicyl­ate

The crystal structure determination of guanidinium 3,5-di­nitro­salicyl­ate, (GU)⁺(DNSA)⁻, CH₆N₃⁺·C₇H₃N₂O₇⁻, has revealed a three-dimensional network polymer comprising hydrogen-bonded cyclic A—B hetero-dimer units [O...N 2.914 and 2.924 (3) Å] linked through peripheral hydrogen bonds between guanidinium H atoms and O atoms (carboxyl­ate, phenolic and nitro) of the DNSA anions [N...O 2.844–3.166 (3) Å].

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.040
• wR factor = 0.133
• Data-to-parameter ratio = 10.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

The nitro-substituted aromatic acid 3,5-dinitrosalicylic acid (DNSA) has proven potential for formation of proton-transfer compounds, particularly because of its acid strength (pK_a = 2.18), its interactive ortho-related phenolic substituent group together with the nitro substituents which have potential for both π–π interactions as well as hydrogen-bonding interactions. A large number of both neutral and proton-transfer compounds of Lewis bases with DNSA, together with their IR spectra have been reported (Hindawey et al., 1980; Issa et al., 1981), while the crystal structures of both the parent acid as the monohydrate DNSA·H₂O (Smith et al., 1995) and several of its adducts are also known: with urea [(DNSA)(UR)] (Smith et al., 1997); with the isomeric aminobenzoic acids (Smith et al., 1995): 2-aminobenzoic acid [(2-ABA)⁺(DNSA)^-], 3-aminobenzoic acid [(3-ABA)⁺(DNSA)^-] and 4-aminobenzoic acid [(4-ABA)(4-ABA)⁺(DNSA)^-]; with 3-amino-1H-1,2,4-triazole [(3-AT)⁺(DNSA)^-] (Smith et al., 1996), with 8-aminoquinoline [(8-AQ)⁺(DNSA)^-] (Smith, Wermuth, Bott et al., 2001), and with 8-quinolinol [(8-HQ)⁺(DNSA)^-] (Smith, Wermuth & White, 2001). In all of these, the hydrogen-bonded interactions following proton transfer are extensive giving stable high melting point solids.

Reported here is the 1:1 proton-transfer compound, (I), of guanidine (GU) with DNSA [(GU)⁺ (DNSA)^-] in which the primary hydrogen-bonding interaction is between both O atoms of the carboxylate group of DNSA and H atoms of two of the amine groups of GU [O71···H832—N83 2.914 (3) Å and O···H—N 178 (2)°; O72···H821—N82 2.924 (3) Å and O···H—N 179 (2)°]. This forms a cyclic eight-membered ring [graph-set R22(8); Etter, 1990] (Fig. 1). The second proton on N82 gives secondary three-centre interactions with the DNSA substituent groups, one to the phenol oxygen [N82—H822···O2 2.904 (3) Å and N—H···O 142 (2)°; symmetry code: 1 - x, 2 - y, 2 - z] and one to a nitro oxygen [N82—H822···O31 3.070 (3) Å and N—H···O, 143 (2)°; symmetry code: 1 - x, 2 - y, 2 - z]. Oxygen O31 is also linked to one of the protons on N81 [O31···H811—N81 2.972 (3) Å and O···H—N 149 (2)°; symmetry code: 1 - x, 2 - y, 2 - z]. The other proton on N81 is also linked to a nitro oxygen [N81—H812···O52 3.166 (3) Å and N—H···O 146 (2)°; symmetry code: 1/2 - x, 3/2 + y, 3/2 - z)], while the second proton on N83 gives a peripheral link to an adjacent carboxyl group [N83—H831···O71 2.844 (3) Å and N—H···O 156 (2)°; symmetry code: 1/2 - x, 1/2 + y, 3/2 - z]. This results in a network polymer (Fig. 2). The phenolic proton participates in an intramolecular hydrogen bond with the carboxylic acid oxygen [O2—H2···O72 2.415 (3) Å and O—H···O 164 (2)°]. This is similar to the situation found for salicylic acid (O···O 2.640 Å; Sundaralingam & Jensen, 1965), and for 3,5-dinitrosalicylic acid (O···O 2.566 Å; Smith et al., 1995). Although this distance is shorter than for these acids, it is comparable with the values for the other known Lewis-base compounds with DNSA (range 2.452–2.460 Å; Smith et al., 1995).

S2. Experimental

The synthesis of the title compound was carried out by refluxing equimolar quantities (1 mmol) of 3,5-dinitrosalicylic acid and guanidine in 20 ml of 50% aqueous ethanol for 15 min at 350 K. Crystals were obtained by room-temperature evaporation of the solvent.

S3. Refinement

The positional parameters for only the atoms involved in intermolecular hydrogen bonding (H2, H811, H812, H821,H822, H831 and H832) were refined. All other H atoms were constrained in the refinement.

Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1996); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN for Windows (Molecular Structure Corporation, 1997-1999); program(s) used to solve structure: SAPI91 (Fan, 1991); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: TEXSAN for Windows and PLATON for Windows (Spek, 1999).

Figures

	Fig. 1. The molecular configuration and atom-numbering scheme for the hydrogen-bonded guanidinium cation and 3,5-dinitrosalicylate anion dimer units in [GU^+][DNSA^-]. Atoms are shown as 50% probability ellipsoids.
	Fig. 2. The hydrogen-bonding scheme (shown as broken lines) viewed down the b-cell direction.

(I)

Crystal data

CH6N3^+·C7H3N2O7^−	F(000) = 592
Mr = 287.19	Dx = 1.647 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71069 Å
a = 9.806 (3) Å	Cell parameters from 25 reflections
b = 5.928 (3) Å	θ = 18.0–20.0°
c = 19.933 (2) Å	µ = 0.15 mm^−1
β = 90.696 (16)°	T = 293 K
V = 1158.6 (7) Å^3	Prism, yellow
Z = 4	0.50 × 0.35 × 0.20 mm

Data collection

Rigaku AFC-7R diffractometer	Rint = 0.024
Radiation source: Rigaku rotating anode	θmax = 25.1°, θmin = 3.6°
Graphite monochromator	h = 0→11
ω–2θ scans	k = 0→7
2172 measured reflections	l = −23→23
2046 independent reflections	3 standard reflections every 150 reflections
1307 reflections with I > 2σ(I)	intensity decay: 0.1%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.040	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.134	w = 1/[σ^2(Fo^2) + (0.069P)^2 + 0.2414P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max = 0.001
2046 reflections	Δρmax = 0.20 e Å^−3
203 parameters	Δρmin = −0.26 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.020 (3)

Special details

Experimental. The scan width was (1.57 + 0.35tanθ)° with an ω scan speed of 16° per minute (up to 5 scans to achieve I/σ(I) > 15). Stationary background counts were recorded at each end of the scan, and the scan time:background time ratio was 2:1.

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
O2	0.65837 (17)	0.6396 (3)	0.98486 (8)	0.0436 (5)
O31	0.83449 (19)	0.4200 (3)	1.06521 (9)	0.0501 (5)
O32	0.98992 (19)	0.2454 (3)	1.00877 (10)	0.0543 (5)
O51	0.8458 (3)	−0.1971 (4)	0.82068 (13)	0.0826 (8)
O52	0.6500 (2)	−0.1372 (4)	0.77317 (10)	0.0611 (6)
O71	0.40088 (18)	0.5676 (3)	0.82569 (9)	0.0502 (5)
O72	0.47063 (17)	0.7643 (3)	0.91460 (9)	0.0456 (5)
N3	0.8750 (2)	0.3251 (4)	1.01429 (11)	0.0390 (5)
N5	0.7390 (3)	−0.0916 (4)	0.81482 (11)	0.0502 (6)
N81	0.0928 (2)	1.2513 (4)	0.82760 (11)	0.0480 (6)
N82	0.2517 (2)	1.0963 (4)	0.90016 (10)	0.0448 (6)
N83	0.1977 (2)	0.9180 (4)	0.80152 (11)	0.0543 (6)
C1	0.5892 (2)	0.4279 (4)	0.88924 (11)	0.0349 (6)
C2	0.6757 (2)	0.4637 (4)	0.94650 (11)	0.0341 (6)
C3	0.7821 (2)	0.3044 (4)	0.95685 (11)	0.0343 (6)
C4	0.8043 (2)	0.1253 (4)	0.91408 (12)	0.0371 (6)
C5	0.7165 (2)	0.0991 (4)	0.86011 (12)	0.0389 (6)
C6	0.6096 (2)	0.2457 (4)	0.84735 (11)	0.0376 (6)
C7	0.4780 (2)	0.5938 (4)	0.87450 (12)	0.0383 (6)
C8	0.1811 (2)	1.0882 (4)	0.84278 (11)	0.0373 (6)
H2	0.574 (3)	0.719 (5)	0.958 (1)	0.065*
H4	0.879	0.010	0.925	0.038*
H6	0.553	0.230	0.805	0.038*
H811	0.089 (2)	1.372 (4)	0.850 (1)	0.048*
H812	0.045 (2)	1.234 (4)	0.792 (1)	0.053*
H821	0.317 (2)	0.998 (4)	0.905 (1)	0.058*
H822	0.247 (2)	1.214 (3)	0.927 (1)	0.053*
H831	0.161 (2)	0.922 (3)	0.759 (1)	0.063*
H832	0.268 (2)	0.800 (4)	0.809 (1)	0.070*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O2	0.0467 (10)	0.0430 (10)	0.0408 (9)	0.0087 (8)	−0.0149 (8)	−0.0066 (8)
O31	0.0548 (11)	0.0580 (13)	0.0374 (10)	0.0037 (9)	−0.0126 (8)	−0.0040 (9)
O32	0.0412 (10)	0.0516 (12)	0.0697 (13)	0.0109 (9)	−0.0169 (9)	−0.0034 (10)
O51	0.0801 (16)	0.0825 (17)	0.0850 (16)	0.0337 (14)	−0.0104 (13)	−0.0368 (14)
O52	0.0715 (13)	0.0644 (14)	0.0471 (11)	−0.0114 (11)	−0.0070 (10)	−0.0148 (10)
O71	0.0476 (11)	0.0609 (12)	0.0417 (10)	0.0051 (9)	−0.0184 (8)	−0.0015 (9)
O72	0.0436 (10)	0.0461 (11)	0.0468 (10)	0.0086 (8)	−0.0130 (8)	−0.0032 (9)
N3	0.0377 (12)	0.0370 (11)	0.0420 (12)	0.0007 (9)	−0.0101 (9)	0.0035 (10)
N5	0.0593 (15)	0.0478 (14)	0.0436 (13)	−0.0025 (12)	0.0042 (11)	−0.0095 (11)
N81	0.0473 (12)	0.0531 (14)	0.0433 (12)	0.0070 (11)	−0.0130 (10)	−0.0051 (11)
N82	0.0506 (13)	0.0463 (13)	0.0373 (11)	0.0076 (10)	−0.0120 (10)	−0.0042 (10)
N83	0.0690 (15)	0.0574 (15)	0.0359 (12)	0.0165 (12)	−0.0170 (11)	−0.0068 (11)
C1	0.0329 (12)	0.0395 (14)	0.0322 (12)	−0.0012 (10)	−0.0020 (9)	0.0035 (10)
C2	0.0344 (12)	0.0337 (13)	0.0340 (12)	−0.0010 (10)	−0.0014 (10)	0.0006 (11)
C3	0.0319 (12)	0.0391 (14)	0.0317 (12)	−0.0026 (10)	−0.0046 (9)	0.0043 (10)
C4	0.0355 (12)	0.0362 (13)	0.0396 (13)	−0.0005 (10)	0.0023 (10)	0.0023 (11)
C5	0.0419 (13)	0.0385 (14)	0.0366 (13)	−0.0045 (11)	0.0044 (11)	−0.0030 (11)
C6	0.0385 (13)	0.0443 (15)	0.0300 (12)	−0.0070 (11)	0.0001 (10)	−0.0015 (11)
C7	0.0374 (13)	0.0444 (15)	0.0329 (12)	−0.0020 (11)	−0.0046 (10)	0.0023 (11)
C8	0.0356 (12)	0.0446 (15)	0.0317 (12)	−0.0005 (12)	−0.0032 (10)	0.0033 (11)

Geometric parameters (Å, º)

O2—C2	1.305 (3)	N82—H821	0.87 (2)
O2—H2	1.09 (2)	N82—H822	0.881 (19)
O31—N3	1.231 (3)	N83—C8	1.313 (3)
O32—N3	1.228 (3)	N83—H831	0.92 (2)
O51—N5	1.224 (3)	N83—H832	0.99 (2)
O52—N5	1.227 (3)	C1—C6	1.381 (3)
O71—C7	1.235 (3)	C1—C2	1.429 (3)
O72—C7	1.291 (3)	C1—C7	1.495 (3)
N3—C3	1.460 (3)	C2—C3	1.420 (3)
N5—C5	1.465 (3)	C3—C4	1.381 (3)
N81—C8	1.330 (3)	C4—C5	1.379 (3)
N81—H811	0.84 (2)	C4—H4	1.02
N81—H812	0.85 (2)	C5—C6	1.383 (4)
N82—C8	1.331 (3)	C6—H6	1.01
C2—O2—H2	99 (2)	O2—C2—C1	120.4 (2)
C7—O72—H2	101 (2)	C3—C2—C1	116.4 (2)
O32—N3—O31	123.8 (2)	C4—C3—C2	122.9 (2)
O32—N3—C3	117.5 (2)	C4—C3—N3	116.5 (2)
O31—N3—C3	118.7 (2)	C2—C3—N3	120.6 (2)
O51—N5—O52	123.5 (2)	C5—C4—C3	117.8 (2)
O51—N5—C5	118.1 (2)	C5—C4—H4	122
O52—N5—C5	118.4 (2)	C3—C4—H4	120
C8—N81—H811	121.9 (14)	C4—C5—C6	122.5 (2)
C8—N81—H812	116.9 (16)	C4—C5—N5	118.1 (2)
H811—N81—H812	121 (2)	C6—C5—N5	119.4 (2)
C8—N82—H821	116.5 (14)	C1—C6—C5	119.7 (2)
C8—N82—H822	121.3 (13)	C1—C6—H6	120
H821—N82—H822	120.5 (19)	C5—C6—H6	120
C8—N83—H831	120.6 (12)	O71—C7—O72	123.2 (2)
C8—N83—H832	122.6 (12)	O71—C7—C1	120.7 (2)
H831—N83—H832	114.9 (17)	O72—C7—C1	116.0 (2)
C6—C1—C2	120.7 (2)	N83—C8—N81	120.1 (2)
C6—C1—C7	120.4 (2)	N83—C8—N82	119.9 (2)
C2—C1—C7	118.9 (2)	N81—C8—N82	120.0 (2)
O2—C2—C3	123.2 (2)
C6—C1—C2—O2	178.1 (2)	C3—C4—C5—C6	0.7 (4)
C7—C1—C2—O2	−0.6 (3)	C3—C4—C5—N5	−179.5 (2)
C6—C1—C2—C3	0.5 (3)	O51—N5—C5—C4	−11.2 (4)
C7—C1—C2—C3	−178.2 (2)	O52—N5—C5—C4	168.7 (2)
O2—C2—C3—C4	−176.5 (2)	O51—N5—C5—C6	168.5 (3)
C1—C2—C3—C4	1.0 (3)	O52—N5—C5—C6	−11.5 (3)
O2—C2—C3—N3	3.1 (4)	C2—C1—C6—C5	−1.4 (4)
C1—C2—C3—N3	−179.4 (2)	C7—C1—C6—C5	177.3 (2)
O32—N3—C3—C4	26.5 (3)	C4—C5—C6—C1	0.8 (4)
O31—N3—C3—C4	−153.4 (2)	N5—C5—C6—C1	−178.9 (2)
O32—N3—C3—C2	−153.1 (2)	C6—C1—C7—O71	1.7 (4)
O31—N3—C3—C2	27.1 (3)	C2—C1—C7—O71	−179.6 (2)
C2—C3—C4—C5	−1.7 (4)	C6—C1—C7—O72	−176.9 (2)
N3—C3—C4—C5	178.8 (2)	C2—C1—C7—O72	1.9 (3)