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The crystal structure of 1-chloro-2-nitro­benzene, C6H4ClNO2, is made up of mol­ecules which are linked by N—O...Cl halogen bonds. These mol­ecular chains are involved in aromatic π–π stacking; the inter­molecular O...Cl distance is 3.09 Å. Such short halogen bonds are not common. A rigid-body analysis including the non-rigidly attached rigid group provides the mean-square amplitudes of the mol­ecular translations and librations, and of the inter­nal torsional vibrations of the nitro group. The results reveal the driving role of the torsional vibrations of the nitro group in the phase transition to the liquid phase.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270106048797/em1004sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270106048797/em1004Isup2.hkl
Contains datablock I

CCDC reference: 638344

Comment top

The investigation of interactions in the crystal structure of the title compound, (I), is part of our studies concerning supramolecular aggregation in 1-substituted nitrobenzenes.

The molecule of (I) is not planar. Fig. 1 shows the molecule with the atom numbering. Table 1 reports selected geometric parameters. The dihedral angle between the planes of the benzene ring and the nitro group is 42.14°. This twist results from a steric effect. The intramolecular Cl···O distance is short, at 2.943 (5) Å.

Quantum-chemical calculations of the geometry of the molecule using GAUSSIAN03 at the RHF/6–31g** basis level (Frisch et al., 2004) indicate a similar geometry, with a dihedral angle of 40.26°. Similar Cl···O interactions have been reported, e.g. for a form of 1-chloro-2,4-dinitrobenzene (Wilkins et al., 1990), 2-chloro-1,3,5-trinitrobezene (Willis et al., 1971) and 1,2-dichloro-3-nitrobenzene (Sharma et al., 1986). The intramolecular Cl···O distances in these crystals are 2.964 (2), 2.924 (2) and 2.999 (2) Å, respectively.

An interaction of a similar nature occurs between the molecules of (I). The intermolecular Cl···O distance from the crystal structure determination is 3.095 (5) Å (Fig. 2). Such an interaction involving a halogen atom and an electronegative hetero atom is called halogen bonding, by analogy with hydrogen bonding (Metrangelo & Resnati, 2001; Ouvrard et al., 2003). In contrast withhydrogen bonding, halogen bonding, Y-halogen···X, is always linear, with the halogen atom pointing to an electron lone pair of a hetero atom. Halogen bonding is an important interaction leading to supramolecular synthons which most often involve I atoms (Saha et al., 2005). In the title structure, the benzene ring, the Cl atom and the nearest O atom of a neighbouring molecule are coplanar. These interactions create a supramolecular synthon in which Cl···O is cis to C—N (Allen et al., 1997). The second scheme illustrates this type of interaction.

Halogen bonding has been observed in the crystal structure of the high-temperature polymorph of para-chloronitrobenzene (Mak & Trotter, 1962). In the crystal structure (Of what?) the Cl···O distances are 3.183 and 3.080 Å at 300 and 100 K, respectively (Mossakowska & Wójcik, 2005). However, only O···O and Cl···Cl interactions occur in the crystal structure of meta-chloronitrobenzene (Gopalakrishna, 1965) and in the low-temperature polymorph of para-chloronitrobenzene (Meriles et al., 2000).

Translationally equivalent along the a crystallographic axis, the molecules of (I) are linked by ππ interactions; the interplanar spacing is 3.566 (5) Å and the centroid offset is 1.375 Å (Fig. 3). Thus supramolecular tapes formed via halogen bonding are involved in molecular stacking via aromatic ππ interactions. Competition between these two types of specific intermolecular interactions results in a layered structure (Figs. 2 and 3), with additional short C—H···O intermolecular contacts (Fig. 3 and Table 2).

A search of the Cambridge Structural Database (April 2006 version; Allen, 2002) resulted in 156 retrieved crystal structures of aromatic compounds with close intermolecular contacts between at least one Cl atom and a nitro group. Among these retrieved structures, 314 close contacts correspond to Cl···O—N interactions, i.e. to one O atom of a nitro group. Fig. 4 shows the distribution of the short Cl···O intermolecular distances in the retrieved structures. The asymmetric histogram reveals that very short O···Cl distances are not common.

The crystal structure of (I) is isostructural with that of 1-bromo-2-nitrobenzene (Fronczek, 2005). The crystal structure of (I) has been determined in this work at a temperature only a few degrees (about 7 K) below the melting point. Although the structure is reliable, the anisotropic displacement parameters show very large values due to pronounced molecular dynamics. In particular, the anisotropic displacement parameters of the nitro group O atoms are large, pointing to strong torsional vibrations of the nitro group. Aromatic molecules fulfil well the exigencies of the rigid-body approximation (Cruickshank, 1956; Dunitz et al., 1988; Schomaker & Trueblood, 1998), especially at elevated temperatures. Calculations within the TLS formalism, with the correlation of the internal vibration of the non-rigidly attached rigid group performed with THMA11 (Farrugia, 1999), enabled the monitoring of molecular motions in the vicinity of the melting point. The mean-square amplitudes of the molecular translations and librations are large (0.035–0.057 Å2 and 16–45°2, respectively). The largest libration occurs about the axis close to the C—Cl bond. The internal torsional vibration of the nitro group occurs about the C—N bond. The mean-square amplitude of the overall nitro group rotation is about 227°2 and may be compared with the librational contribution to the motion (from the molecular libration), which is about 31°2. The results of the rigid-body analysis of the crystal structure of (I) reveal the driving role of the torsional vibrations of the nitro group in the phase transition to the liquid phase.

Related literature top

For related literature, see: Allen (2002); Allen et al. (1997); Cruickshank (1956); Dunitz et al. (1988); Farrugia (1999); Frisch (2004); Fronczek (2005); Gopalakrishna (1965); Mak & Trotter (1962); Meriles et al. (2000); Metrangelo & Resnati (2001); Mossakowska & Wójcik (2005); Ouvrard et al. (2003); Saha et al. (2005); Schomaker & Trueblood (1998); Sharma et al. (1986); Wilkins et al. (1990); Willis et al. (1971).

Experimental top

Commercially available (POCH Poland) ortho-chloronitrobenzene, (I), was not purified further and was not recrystallized. The crystals sublime on exposure to the atmosphere (m.p. 304–306 K) and had to be enclosed and sealed within thin-walled glass capillaries in order to use them for collecting X-ray intensity data.

Refinement top

All H atoms were treated as riding atoms, with C—H = 0.93 Å, and were refined isotropically, with Uiso(H) = 1.2Ueq(C). [Please check added text]

Computing details top

Data collection: KM-4 CCD Software (Kuma Diffraction, 1999); cell refinement: KM-4 CCD Software; data reduction: KM-4 CCD Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability and H atoms are shown as small spheres of arbitrary radii.
[Figure 2] Fig. 2. A projection of the crystal structure of (I) onto (100), showing the intermolecular O···Cl contacts (dashed lines).
[Figure 3] Fig. 3. A projection of the crystal structure of (I) onto (010), showing the short Cl···O and C—H···O intermolecular interactions (dashed lines).
[Figure 4] Fig. 4. Histogram illustrating the distances between the Cl atom and the nitro group O atom for 156 compounds in the Cambridge Structural Database. For details, see text.
1-chloro,2-nitrobenzene top
Crystal data top
C6H4ClNO2F(000) = 320
Mr = 157.55Dx = 1.555 Mg m3
Monoclinic, P21/nMelting point = 304–306 K
Hall symbol: -P 2ynMo Kα radiation, λ = 0.71073 Å
a = 3.821 (1) ÅCell parameters from 1188 reflections
b = 11.725 (2) Åθ = 3.7–22.4°
c = 15.118 (3) ŵ = 0.50 mm1
β = 96.55 (3)°T = 298 K
V = 672.9 (2) Å3Block, pale yellow
Z = 40.89 × 0.55 × 0.55 mm
Data collection top
Kuma KM-4 CCD area-detector
diffractometer
975 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.083
Graphite monochromatorθmax = 25.8°, θmin = 5.4°
ω scansh = 24
2711 measured reflectionsk = 1314
1214 independent reflectionsl = 1818
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.075Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.205H-atom parameters constrained
S = 1.09 w = 1/[σ2(Fo2) + (0.0867P)2 + 0.8782P]
where P = (Fo2 + 2Fc2)/3
1214 reflections(Δ/σ)max = 0.019
91 parametersΔρmax = 0.52 e Å3
0 restraintsΔρmin = 0.45 e Å3
Crystal data top
C6H4ClNO2V = 672.9 (2) Å3
Mr = 157.55Z = 4
Monoclinic, P21/nMo Kα radiation
a = 3.821 (1) ŵ = 0.50 mm1
b = 11.725 (2) ÅT = 298 K
c = 15.118 (3) Å0.89 × 0.55 × 0.55 mm
β = 96.55 (3)°
Data collection top
Kuma KM-4 CCD area-detector
diffractometer
975 reflections with I > 2σ(I)
2711 measured reflectionsRint = 0.083
1214 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0750 restraints
wR(F2) = 0.205H-atom parameters constrained
S = 1.09Δρmax = 0.52 e Å3
1214 reflectionsΔρmin = 0.45 e Å3
91 parameters
Special details top

Experimental. The crystal structure is determined at the temperature close to the melting point. Very large displacement parameters are discussed in the paper.

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 (Å2) top
xyzUiso*/Ueq
Cl10.6920 (3)0.45536 (9)0.36968 (10)0.0772 (5)
N10.5122 (11)0.2746 (3)0.2224 (2)0.0669 (10)
O10.4063 (16)0.3650 (3)0.1946 (3)0.1232 (19)
O20.6344 (13)0.2045 (3)0.1770 (2)0.1062 (15)
C10.5329 (10)0.3205 (3)0.3840 (3)0.0501 (9)
C20.4672 (9)0.2440 (3)0.3146 (2)0.0480 (9)
C30.3535 (10)0.1345 (3)0.3291 (3)0.0545 (10)
H30.31630.08320.28200.065*
C40.2958 (11)0.1019 (4)0.4129 (3)0.0596 (10)
H40.21400.02890.42290.072*
C50.3592 (11)0.1776 (4)0.4825 (3)0.0635 (11)
H50.31840.15540.53950.076*
C60.4822 (12)0.2855 (4)0.4686 (3)0.0618 (11)
H60.53130.33510.51640.074*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0804 (9)0.0480 (7)0.1045 (11)0.0046 (5)0.0152 (7)0.0038 (5)
N10.098 (3)0.053 (2)0.0515 (19)0.0150 (19)0.0152 (18)0.0125 (17)
O10.219 (6)0.077 (3)0.076 (2)0.043 (3)0.029 (3)0.029 (2)
O20.177 (4)0.085 (3)0.065 (2)0.030 (3)0.046 (3)0.0085 (19)
C10.0500 (19)0.0435 (19)0.058 (2)0.0061 (15)0.0097 (16)0.0036 (16)
C20.0503 (19)0.051 (2)0.0427 (18)0.0102 (15)0.0046 (14)0.0046 (16)
C30.063 (2)0.047 (2)0.054 (2)0.0067 (16)0.0051 (17)0.0004 (17)
C40.064 (2)0.052 (2)0.064 (2)0.0003 (18)0.0115 (19)0.011 (2)
C50.073 (3)0.067 (3)0.053 (2)0.010 (2)0.018 (2)0.0101 (19)
C60.071 (3)0.065 (3)0.050 (2)0.010 (2)0.0071 (18)0.0104 (19)
Geometric parameters (Å, º) top
Cl1—C11.717 (4)C3—C41.365 (6)
N1—O11.194 (5)C3—H30.9300
N1—O21.199 (5)C4—C51.377 (6)
N1—C21.468 (5)C4—H40.9300
C1—C61.377 (6)C5—C61.375 (6)
C1—C21.382 (5)C5—H50.9300
C2—C31.380 (5)C6—H60.9300
O1—N1—O2123.0 (4)C2—C3—H3120.2
O1—N1—C2118.7 (4)C3—C4—C5119.8 (4)
O2—N1—C2118.1 (3)C3—C4—H4120.1
C6—C1—C2118.7 (4)C5—C4—H4120.1
C6—C1—Cl1118.7 (3)C4—C5—C6120.6 (4)
C2—C1—Cl1122.6 (3)C4—C5—H5119.7
C3—C2—C1121.1 (3)C6—C5—H5119.7
C3—C2—N1116.8 (3)C1—C6—C5120.2 (4)
C1—C2—N1122.1 (4)C1—C6—H6119.9
C4—C3—C2119.6 (4)C5—C6—H6119.9
C4—C3—H3120.2
C6—C1—C2—C30.1 (6)C1—C2—C3—C41.7 (6)
Cl1—C1—C2—C3177.2 (3)N1—C2—C3—C4177.9 (4)
C6—C1—C2—N1179.5 (4)C2—C3—C4—C51.5 (6)
Cl1—C1—C2—N13.1 (5)C3—C4—C5—C60.4 (7)
O1—N1—C2—C3136.2 (5)C4—C5—C6—C12.1 (7)
O2—N1—C2—C339.4 (6)C2—C1—C6—C51.8 (6)
O1—N1—C2—C143.5 (7)Cl1—C1—C6—C5179.2 (3)
O2—N1—C2—C1141.0 (5)

Experimental details

Crystal data
Chemical formulaC6H4ClNO2
Mr157.55
Crystal system, space groupMonoclinic, P21/n
Temperature (K)298
a, b, c (Å)3.821 (1), 11.725 (2), 15.118 (3)
β (°) 96.55 (3)
V3)672.9 (2)
Z4
Radiation typeMo Kα
µ (mm1)0.50
Crystal size (mm)0.89 × 0.55 × 0.55
Data collection
DiffractometerKuma KM-4 CCD area-detector
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
2711, 1214, 975
Rint0.083
(sin θ/λ)max1)0.611
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.075, 0.205, 1.09
No. of reflections1214
No. of parameters91
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.52, 0.45

Computer programs: KM-4 CCD Software (Kuma Diffraction, 1999), KM-4 CCD Software, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2006), SHELXL97.

Selected geometric parameters (Å, º) top
Cl1—C11.717 (4)N1—C21.468 (5)
N1—O11.194 (5)C2—C31.380 (5)
N1—O21.199 (5)
O1—N1—O2123.0 (4)C2—C1—Cl1122.6 (3)
O1—N1—C2118.7 (4)C3—C2—C1121.1 (3)
C6—C1—C2118.7 (4)C3—C2—N1116.8 (3)
C6—C1—Cl1118.7 (3)C1—C2—N1122.1 (4)
Short intermolecular contacts (Å) in (I) top
O2···Cl1i3.095 (5)
O1···H4ii2.62 (5)
O1···C4ii3.266 (4)
Symmetry codes: (i) 3/2-x, -1/2+y, 1/2-z; (ii) 1/2-x, 1/2+y, 1/2-z.
 

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