Imidazolium 2-chloro-4-nitro­benzoate

The cations and anions of the title compound, C₃H₅N₂⁺·C₇H₃ClNO₄⁻, are connected by N—H...O hydrogen bonds to afford a 2₁ helical chain. There are two important C—H...O interactions which link the chains.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.032
• wR factor = 0.076
• Data-to-parameter ratio = 14.3

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



PLAT_162  Alert C Missing or Zero su (esd) on y-coordinate for .       CL

PLAT_353  Alert C Long  N-H Bond (0.87A)     N(3)   -   H(6)   =       1.03 Ang.

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           29.99
         From the CIF: _reflns_number_total               2652
         Count of symmetry unique reflns         1814
         Completeness (_total/calc)            146.20%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured       838
         Fraction of Friedel pairs measured     0.462
         Are heavy atom types Z>Si present          yes
          WARNING: Large fraction of Friedel related reflns may
                   be needed to determine absolute structure


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 2 Alert Level C = Please check

---

S1. Comment

The title compound, (I), was investigated as part of a study on D—H···A hydrogen bonding (D: N, O or C; A: N, O or Cl) in chloro- and nitro-substituted benzoic acid–amine systems (Ishida et al. 2001a,b,c). This is the first report of an enantiomorphic crystal in chloro- and nitro-substituted benzoic acid-amine systems.

An acid–base interaction involving a proton transfer is observed as expected from the high basicity of the present amine (Fig. 1). The cations and anions are held together by short N—H···O hydrogen bonds (Table 2), forming a 2₁ helical chain along the b axis (Fig. 2). The nitro and carboxyl groups are considerably twisted out of the benzene ring; the dihedral angle between the nitro group and the benzene ring is 11.9 (2)° and that between the carboxyl group and the benzene ring is 63.9 (2)°. The dihedral angle between the imidazolium ion and the benzene ring is 14.8 (2)°. There are two leading C—H···O interactions (Table 2) which connect the helical chains.

Usually, 2-chloro-4-nitrobenzoate ion is classified as an achiral molecule because of the rotational flexibility of the nitro and carboxyl groups around the C—N and C—C bond axes, respectively. In crystals, however, the rotation of these groups is hindered by intermolecular interactions and hence the dihedral angles of these groups to the benzene ring may be restricted to certain values other than 0 and 90°. The present result gives an evidence of resolution in a chirality of the benzoate ion by a helical chain formation via a hydrogen bonding in the solid state.

S2. Experimental

No text.

S3. Refinement

H atoms were refined isotropically.

Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1990); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN for Windows (MSC, 1997-1999); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: TEXSAN for Windows.

Figures

	Fig. 1. ORTEP-3 (Farrugia, 1997) drawing of (I) with the atom labeling. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level.
	Fig. 2. Packing diagram showing a 21 helical structure formed via N—H···O hydrogen bonds indicated by dashed lines. C—H···O interactions which connect the helical chains are indicated by dotted lines (symmetry codes are as in Table 2).

(I)

Crystal data

C3H5N2^+·C7H3ClNO4^−	F(000) = 276.0
Mr = 269.64	Dx = 1.564 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 25 reflections
a = 9.078 (2) Å	θ = 11.9–12.4°
b = 5.928 (2) Å	µ = 0.34 mm^−1
c = 10.7711 (18) Å	T = 298 K
β = 98.998 (17)°	Prismatic, colorless
V = 572.5 (2) Å^3	0.40 × 0.30 × 0.20 mm
Z = 2

Data collection

Rigaku AFC-5R diffractometer	2141 reflections with I > 2σ(I)
Radiation source: Rigaku rotating anode	Rint = 0.014
Graphite monochromator	θmax = 30.0°, θmin = 1.9°
ω–2θ scans	h = −4→12
Absorption correction: ψ scans (North et al., 1968)	k = −3→8
Tmin = 0.874, Tmax = 0.934	l = −15→15
3945 measured reflections	3 standard reflections every 97 reflections
2652 independent reflections	intensity decay: −3.4%

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.032	w = 1/[σ^2(Fo^2) + (0.032P)^2 + 0.0911P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.076	(Δ/σ)max = 0.001
S = 1.04	Δρmax = 0.19 e Å^−3
2652 reflections	Δρmin = −0.23 e Å^−3
186 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.012 (3)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack, 1983
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.02 (6)

Special details

Experimental. The scan width was (1.31 + 0.30tanθ)° with an ω scan speed of 5° per minute (up to 3 scans to achieve I/σ(I) > 10). 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
Cl	0.45183 (6)	0.0000	0.29755 (5)	0.04751 (16)
O1	0.74535 (15)	0.4499 (4)	0.22182 (14)	0.0495 (5)
O2	0.62065 (16)	0.4708 (4)	0.38425 (13)	0.0537 (5)
O3	0.01305 (18)	0.1510 (4)	−0.06683 (15)	0.0621 (6)
O4	0.07838 (19)	0.4224 (4)	−0.17668 (15)	0.0594 (5)
N1	0.09824 (19)	0.2993 (4)	−0.08466 (16)	0.0395 (5)
N2	1.02363 (19)	0.4034 (4)	0.34032 (16)	0.0415 (5)
N3	1.2021 (2)	0.2496 (4)	0.46630 (17)	0.0472 (5)
C1	0.4868 (2)	0.3989 (4)	0.18143 (16)	0.0277 (4)
C2	0.3997 (2)	0.2080 (4)	0.18574 (16)	0.0305 (4)
C3	0.2705 (2)	0.1727 (4)	0.09930 (18)	0.0323 (4)
C4	0.2327 (2)	0.3355 (4)	0.00901 (17)	0.0303 (4)
C5	0.3142 (2)	0.5281 (4)	0.00019 (17)	0.0331 (5)
C6	0.4427 (2)	0.5574 (4)	0.08744 (18)	0.0321 (5)
C7	0.6310 (2)	0.4420 (4)	0.27148 (17)	0.0334 (5)
C8	1.0628 (3)	0.2256 (5)	0.4102 (2)	0.0456 (6)
C9	1.2542 (2)	0.4500 (5)	0.4300 (2)	0.0510 (7)
C10	1.1424 (2)	0.5479 (5)	0.3511 (2)	0.0473 (6)
H1	0.218 (2)	0.046 (4)	0.1032 (19)	0.038 (6)*
H2	0.282 (2)	0.639 (4)	−0.063 (2)	0.041 (6)*
H3	0.502 (2)	0.690 (5)	0.083 (2)	0.038 (6)*
H4	0.924 (3)	0.417 (6)	0.286 (3)	0.076 (9)*
H5	1.000 (3)	0.103 (4)	0.419 (2)	0.047 (7)*
H6	1.259 (3)	0.133 (6)	0.526 (3)	0.083 (10)*
H7	1.354 (3)	0.509 (5)	0.458 (2)	0.061 (7)*
H8	1.142 (3)	0.688 (6)	0.304 (2)	0.056 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl	0.0582 (3)	0.0378 (3)	0.0403 (2)	−0.0027 (3)	−0.0116 (2)	0.0075 (3)
O1	0.0226 (6)	0.0747 (16)	0.0480 (8)	−0.0026 (8)	−0.0050 (6)	−0.0020 (9)
O2	0.0458 (8)	0.0766 (15)	0.0350 (6)	−0.0165 (9)	−0.0053 (6)	−0.0144 (9)
O3	0.0396 (9)	0.0869 (15)	0.0543 (10)	−0.0306 (10)	−0.0096 (7)	0.0041 (10)
O4	0.0554 (10)	0.0678 (14)	0.0451 (8)	−0.0080 (10)	−0.0227 (7)	0.0114 (8)
N1	0.0270 (8)	0.0523 (13)	0.0354 (9)	−0.0035 (8)	−0.0071 (7)	−0.0043 (8)
N2	0.0296 (9)	0.0551 (13)	0.0360 (8)	0.0028 (9)	−0.0063 (7)	0.0021 (8)
N3	0.0396 (10)	0.0612 (16)	0.0373 (9)	0.0118 (10)	−0.0054 (8)	0.0080 (9)
C1	0.0223 (8)	0.0315 (11)	0.0282 (8)	−0.0019 (8)	0.0003 (6)	−0.0072 (8)
C2	0.0303 (9)	0.0316 (11)	0.0279 (8)	0.0012 (9)	−0.0004 (7)	0.0004 (8)
C3	0.0281 (9)	0.0345 (12)	0.0327 (9)	−0.0081 (9)	0.0000 (7)	−0.0023 (9)
C4	0.0199 (8)	0.0398 (12)	0.0289 (8)	0.0004 (8)	−0.0031 (7)	−0.0037 (8)
C5	0.0294 (9)	0.0380 (13)	0.0303 (8)	0.0012 (9)	−0.0007 (7)	0.0025 (9)
C6	0.0288 (9)	0.0327 (13)	0.0340 (9)	−0.0057 (8)	0.0021 (7)	−0.0004 (8)
C7	0.0276 (9)	0.0335 (13)	0.0352 (9)	−0.0039 (9)	−0.0073 (7)	−0.0020 (8)
C8	0.0413 (12)	0.0552 (17)	0.0377 (10)	−0.0010 (12)	−0.0019 (9)	0.0067 (11)
C9	0.0304 (10)	0.075 (2)	0.0437 (10)	−0.0055 (12)	−0.0066 (8)	0.0092 (12)
C10	0.0387 (12)	0.0556 (19)	0.0434 (11)	−0.0013 (11)	−0.0065 (9)	0.0089 (11)

Geometric parameters (Å, º)

Cl—C2	1.737 (2)	C1—C6	1.393 (3)
O1—C7	1.241 (2)	C1—C7	1.524 (2)
O2—C7	1.245 (2)	C2—C3	1.395 (2)
O3—N1	1.206 (3)	C3—C4	1.375 (3)
O4—N1	1.221 (2)	C3—H1	0.89 (3)
N1—C4	1.473 (2)	C4—C5	1.372 (3)
N2—C8	1.311 (3)	C5—C6	1.390 (3)
N2—C10	1.368 (3)	C5—H2	0.96 (2)
N2—H4	1.00 (3)	C6—H3	0.96 (2)
N3—C8	1.321 (3)	C8—H5	0.94 (3)
N3—C9	1.358 (4)	C9—C10	1.349 (3)
N3—H6	1.03 (3)	C9—H7	0.97 (3)
C1—C2	1.385 (3)	C10—H8	0.97 (3)
O1···N2	2.661 (2)	O3···N1^iii	2.923 (3)
O1···N1^i	3.024 (3)	O3···C4^iii	3.049 (3)
O1···O3^i	3.188 (3)	O3···O4^iii	3.176 (3)
O2···N3^ii	2.665 (3)	O3···N2^iv	3.261 (3)
O3—N1—O4	123.23 (17)	C3—C4—N1	118.11 (18)
O3—N1—C4	118.70 (18)	C4—C5—C6	117.50 (19)
O4—N1—C4	118.07 (19)	C4—C5—H2	120.8 (14)
C8—N2—C10	108.37 (19)	C6—C5—H2	121.7 (14)
C8—N2—H4	123 (2)	C5—C6—C1	121.5 (2)
C10—N2—H4	128.9 (19)	C5—C6—H3	119.4 (14)
C8—N3—C9	108.3 (2)	C1—C6—H3	119.2 (14)
C8—N3—H6	124.6 (18)	O1—C7—O2	127.68 (17)
C9—N3—H6	127.0 (17)	O1—C7—C1	115.17 (16)
C2—C1—C6	118.37 (16)	O2—C7—C1	117.12 (17)
C2—C1—C7	123.59 (18)	N2—C8—N3	109.3 (2)
C6—C1—C7	118.01 (18)	N2—C8—H5	124.6 (15)
C1—C2—C3	121.66 (18)	N3—C8—H5	126.1 (15)
C1—C2—Cl	120.56 (14)	C10—C9—N3	107.2 (2)
C3—C2—Cl	117.75 (17)	C10—C9—H7	127.9 (17)
C4—C3—C2	117.24 (19)	N3—C9—H7	124.9 (17)
C4—C3—H1	123.2 (14)	C9—C10—N2	106.8 (2)
C2—C3—H1	119.6 (14)	C9—C10—H8	129.6 (16)
C5—C4—C3	123.74 (17)	N2—C10—H8	123.5 (15)
C5—C4—N1	118.14 (18)
C6—C1—C2—C3	−0.3 (3)	N1—C4—C5—C6	−178.51 (19)
C7—C1—C2—C3	−178.3 (2)	C4—C5—C6—C1	−0.8 (3)
C6—C1—C2—Cl	177.95 (15)	C2—C1—C6—C5	0.6 (3)
C7—C1—C2—Cl	−0.1 (3)	C7—C1—C6—C5	178.75 (19)
C1—C2—C3—C4	0.1 (3)	C2—C1—C7—O1	116.0 (2)
Cl—C2—C3—C4	−178.18 (15)	C6—C1—C7—O1	−62.1 (3)
C2—C3—C4—C5	−0.2 (3)	C2—C1—C7—O2	−65.9 (3)
C2—C3—C4—N1	178.84 (19)	C6—C1—C7—O2	116.1 (2)
O3—N1—C4—C5	−168.3 (2)	C10—N2—C8—N3	0.3 (3)
O4—N1—C4—C5	11.4 (3)	C9—N3—C8—N2	−0.5 (3)
O3—N1—C4—C3	12.5 (3)	C8—N3—C9—C10	0.5 (3)
O4—N1—C4—C3	−167.7 (2)	N3—C9—C10—N2	−0.3 (3)
C3—C4—C5—C6	0.6 (3)	C8—N2—C10—C9	0.0 (3)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H4···O1	1.00 (3)	1.67 (3)	2.661 (2)	169 (3)
N3—H6···O2^v	1.03 (3)	1.65 (3)	2.665 (3)	169 (3)
C5—H2···O1^i	0.96 (2)	2.50 (2)	3.444 (3)	168.0 (15)
C10—H8···O4^i	0.97 (3)	2.64 (3)	3.361 (3)	131 (2)

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