Hydrogen bonding in C-substituted nitro­anilines: simple C(8) chains in 2-bromo-6-chloro-4-nitro­aniline

Glidewell, C.; Low, J.N.; Skakle, J.M.S.; Wardell, J.L.

doi:10.1107/S0108270105010085

organic compounds

STRUCTURAL
CHEMISTRY

ISSN: 2053-2296

Volume 61| Part 5| May 2005| Pages o336-o338

doi:10.1107/S0108270105010085

Hydrogen bonding in C-substituted nitroanilines: simple C(8) chains in 2-bromo-6-chloro-4-nitroaniline

Christopher Glidewell,^a ^* John N. Low,^b Janet M. S. Skakle ^b and James L. Wardell ^c

^aSchool of Chemistry, University of St Andrews, Fife KY16 9ST, Scotland, ^bDepartment of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen AB24 3UE, Scotland, and ^cInstituto de Química, Departamento de Química Inorgânica, Universidade Federal do Rio de Janeiro, 21945-970 Rio de Janeiro, RJ, Brazil
^*Correspondence e-mail: cg@st-andrews.ac.uk

(Received 29 March 2005; accepted 30 March 2005; online 30 April 2005)

In the title compound, C₆H₄BrClN₂O₂, the Br and Cl substituents are disordered over two sites, and the intramolecular dimensions provide evidence for charge polarization. The molecules are linked into C(8) chains by a single N—H⋯O hydrogen bond.

Comment

We report here the structure of the title compound, (I), which we compare with the structures of four other closely related 2,6-substituted 4-nitroanilines, namely 2,6-dichloro-4-nitroaniline, (II) (Hughes & Trotter, 1971 ), 2,6-dibromo-4-nitroaniline, (III) (Bryant et al., 1998 ), 2-bromo-6-cyano-4-nitroaniline, (IV) (Glidewell et al., 2002 ), and 2-iodo-6-methoxy-4-nitroaniline, (V) (Garden et al., 2005 ).

In molecules of (I) (Fig. 1), the Br and Cl substituents are disordered between the 2- and 6-positions in the aryl ring. Refinement of the site occupancies showed that position 2 is occupied equally by the two substituents, whereas there is slight preponderance of Cl at position 6, corresponding to co-crystallization of (I) with 10% of the dichloro analogue (II); compound (II) is isomorphous with (I) but not strictly isostructural. The sample of (I) originated in an industrial preparation using bromination of 2-chloro-4-nitroaniline and it seems likely that the 2,6-dichloro compound (II) may have been present as an impurity before the bromination step.

The C—C bond distances in (I) show marked bond fixation (Table 1), with the C2—C3 and C5—C6 distances significantly shorter than the rest; correspondingly, the two C—N distances are both short for their types (Allen et al., 1987 ), while the N—O distances are both long. These observations taken all together point to the importance of the charge-separated form (Ia) (see scheme) as an important contributor to the overall molecular–electronic structure, as commonly found in 4-nitroanilines. Consistent with the contribution of form (Ia), the dihedral angle between the nitro group and the aryl ring is only 6.6 (2)°.

The molecules of (I) are linked into simple chains by a single N—H⋯O hydrogen bond (Table 2). Amine atom N1 in the molecule at (x, y, z) acts as a hydrogen-bond donor, via H1A, to nitro atom O41 in the molecule at (1 − x, − $[{1\over 2}]$ + y, $[3 \over 2]$ − z), so forming a C(8) chain (Bernstein et al., 1995 ) running parallel to the [010] direction and generated by the 2₁ screw axis along ( $[{1\over 2}]$ , y, $[{3\over 4}]$ ) (Fig. 2). Two antiparallel chains of this type, related to one another by inversion, pass through each unit cell, but there are no direction specific interactions between adjacent chains; in particular, there are no potential acceptors in other chains within hydrogen-bonding distance of H1B.

In (II), the molecules are again linked by a single N—H⋯O hydrogen bond into C(8) chains virtually identical to those in (I) (Hughes & Trotter, 1971). Hence, the presence of a small proportion of (II) co-crystallized with (I) appears to have no significant influence on the supramolecular structure adopted by (I), which in addition retains the sharp melting point of the pure compound (Körner & Contardi, 1914 ). In contrast to the very simple aggregation in (I) and (II), the molecules of (III), which lie across mirror planes in space group P2₁/m, are linked by paired N—H⋯O hydrogen bonds into C(8)[R₂²(6)] chains of rings, further linked into sheets by bromo–nitro interactions (Bryant et al., 1998). In compound (IV), the molecules are linked by a combination of one N—H⋯O and one N—H⋯N hydrogen bond into sheets of alternating R₂²(12) and R₆⁶(36) rings (Glidewell et al., 2002), while in compound (V), hydrogen-bonded C(8)C(8)[R₂²(6)] chains of rings are linked into quite complex ribbons by two-centre iodo–nitro interactions (Garden et al., 2005). In each of (III)–(V), the two N—H bonds of the amine group both participate in the hydrogen bonding, in contrast to the situation in (I) and (II), where one of the N—H bonds plays no role in the supramolecular aggregation.

Figure 1
A molecule of (I)

, showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. For clarity, only one substituent is drawn bonded to C2 and to C6.

Figure 2
Part of the crystal structure of (I)

, showing the formation of a hydrogen-bonded C(8) chain along [010]. For clarity, only one substituent is drawn bonded to C2 and to C6, and H atoms bonded to C atoms have been omitted. Atoms marked with an asterisk (*) or a hash (#) are at the symmetry positions (1 − x, − $[{1\over 2}]$ + y, $[{3\over 2}]$ − z) and (1 − x, $[{1\over 2}]$ + y, $[{3\over 2}]$ − z), respectively.

Experimental

The sample of (I) employed was a gift from ICI; crystals suitable for single-crystal X-ray diffraction were grown by slow evaporation of a solution in ethanol [m.p. 450–452 K; literature m.p. 450 K (Körner & Contardi, 1914)].

Crystal data

C₆H₄Br_0.90Cl_1.10N₂O₂
M_r = 247.02
Monoclinic, P 2₁ /c
a = 3.8052 (3) Å
b = 17.9667 (13) Å
c = 12.0417 (9) Å
β = 93.224 (2)°
V = 821.95 (11) Å³
Z = 4
D_x = 1.996 Mg m⁻³
Mo Kα radiation
Cell parameters from 1863 reflections
θ = 2.0–27.5°
μ = 4.83 mm⁻¹
T = 298 (2) K
Plate, red
0.49 × 0.16 × 0.06 mm

Data collection

Bruker SMART 1000 CCD area detector diffractometer
φ–ω scans
Absorption correction: multi-scan(SADABS; Bruker, 2000 )T_min = 0.201, T_max = 0.749
5904 measured reflections
1863 independent reflections
1357 reflections with I > 2σ(I)
R_int = 0.037
θ_max = 27.5°
h = −4 → 4
k = −23 → 16
l = −15 → 15

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.040
wR(F²) = 0.087
S = 1.02
1863 reflections
129 parameters
H-atom parameters constrained
w = 1/[σ²(F_o²) + (0.0477P)²] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max = 0.001
Δρ_max = 0.50 e Å⁻³
Δρ_min = −0.38 e Å⁻³

Table 1
Selected interatomic distances (Å)

C1—C2	1.408 (4)
C2—C3	1.373 (4)
C3—C4	1.387 (5)
C4—C5	1.387 (5)
C5—C6	1.364 (5)
C6—C1	1.404 (5)
C1—N1	1.345 (4)
C4—N4	1.456 (5)
N4—O41	1.241 (4)
N4—O42	1.228 (4)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯O41ⁱ	0.86	2.25	3.026 (4)	151
Symmetry code: (i) $[-x+1, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ .

The space group P2₁/c was uniquely assigned from the systematic absences. All H atoms were located from difference maps and then treated as riding atoms, with C—H distances of 0.93 Å and N—H distances of 0.86 Å, and with U_iso(H) values of 1.2U_eq(C,N). It was apparent from an early stage that the Cl and Br substituents were disordered between the sites bonded to C2 and C6. Refinement of the site-occupancy factors for the substituents at C2 led to values of 0.503 (6) and 0.497 (6) for Cl and Br, respectively; these were thereafter fixed at 0.50. Refinement of the site-occupancy factors for the substituents at C6 led to values of 0.603 (5) and 0.397 (5) for Cl and Br, respectively; these were thereafter fixed at 0.60 and 0.40, respectively. Refinements with the occupancy factors for all the halogen sites fixed at 0.50 (to force equal populations of Cl and Br) led to significantly higher R values and hence this model was decisively rejected. Because of the fairly close similarity between the C—Cl and C—Br distances, it was necessary to apply DFIX restraints to the four independent C—X (X = Cl and Br) distances.

Data collection: SMART (Bruker, 1998 ); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: OSCAIL (McArdle, 2003 ) and SHELXS97 (Sheldrick, 1997 ); program(s) used to refine structure: OSCAIL and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003 ); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S0108270105010085/sk1832sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S0108270105010085/sk1832Isup2.hkl

Comment top

We report here the structure of the title compound (I), which we compare with the structures of four other closely related 2,6-substituted 4-nitroanilines, namely 2,6-dichloro-4-nitroaniline, (II) (Hughes & Trotter, 1971), 2,6-dibromo-4-nitroaniline, (III) (Bryant et al., 1998), 2-bromo-6-cyano-4-nitroaniline, (IV) (Glidewell et al., 2002), and 2-iodo-6-methoxy-4-nitroaniline, (V) (Garden et al., 2005).

In molecules of (I) (Fig. 1), the Br and Cl substituents are disordered between the 2- and 6-positions in the aryl ring. Refinement of the site occupancies showed that position 2 is occupied equally by the two substituents, whereas there is slight preponderance of Cl at position 6, corresponding to cocrystallization of (I) with 10% of the dichloro analogue (II), which is isomorphous with (I) but not strictly isostructural. The sample of (I) originated in an industrial preparation using bromination of 2-chloro-4-nitroaniline, and it seems likely that the 2,6-dichloro compound (II) may have been present as an impurity before the bromination step.

The C—C bond distances in (I) show marked bond fixation (Table 1), with the C2—C3 and C5—C6 distances significantly shorter than the rest; correspondingly, the two C—N distances are both short for their types (Allen et al., 1987), while the N—O distances are both long. These observations taken all together point to the importance of the charge-separated form (Ia) as an important contributor to the overall molecular–electronic structure, as commonly found in 4-nitroanilines. Consistent with the contribution of form (Ia), the dihedral angle between the nitro group and the aryl ring is only 6.6 (2)°.

The molecules of (I) are linked into simple chains by a single N—H···O hydrogen bond (Table 2). Amine atom N1 in the molecule at (x, y, z) acts as hydrogen-bond donor, via H1A, to nitro atom O41 in the molecule at (1 − x, −1/2 + y, 1.5 − z), so forming a C(8) chain (Bernstein et al., 1995) running parallel to he [010] direction and generated by the 2₁ screw axis along (1/2, y, 3/4) (Fig. 2). Two antiparallel chains of this type, related to one another by inversion, pass through each unit cell, but there are no direction specific interactions between adjacent chains; in particular, there are no potential acceptors in other chains within hydrogen bonding distance of H1B.

In compound (II), the molecules are again linked by a single N—H···O hydrogen bond into C(8) chains virtually identical to those in compound (I) (Hughes & Trotter, 1971). Hence the presence of a small proportion of (II) cocrystallized with (I) appears to have no significant influence on the supramolecular structure adopted by (I), which in addition retains the sharp melting point of the pure compound (Körner & Contardi, 1914). In contrast to the very simple aggregation in (I) and (II), the molecules of (III), which lie across mirror planes in space group P2₁/m, are linked by paired N—H···O hydrogen bonds into C(8)[R²₂(6)] chains of rings, further linked into sheets by bromo–nitro interactions (Bryant et al., 1998). In compound (IV), the molecules are linked by a combination of one N—H···O and one N—H···N hydrogen bond into sheets of alternating R²₂(12) and R⁶₆(36) rings (Glidewell et al., 2002), while in compound (V), hydrogen-bonded C(8)C(8)[R²₂(6)] chains of rings are linked into quite complex ribbons by two-centre iodo–nitro interactions (Garden et al., 2005). In each of (III)–(V), the two N—H bonds of the amine group both participate in the hydrogen bonding, in contrast to the situation in (I) and (II), where one of the N—H bonds plays no role in the supramolecular aggregation.

Experimental top

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: OSCAIL and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).

Figures top

	Fig. 1. A molecule of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. For clarity, only one substituent is drawn bonded to C2 and to C6.
	Fig. 2. Part of the crystal structure of compound (I), showing the formation of a hydrogen-bonded C(8) chain along [010]. For clarity, only one substituent is drawn bonded to C2 and to C6, and H atoms bonded to C atoms have been omitted. Atoms marked with an asterisk (*) or a hash (#) are at the symmetry positions (1 − x, −1/2 + y, 3/2 − z) and (1 − x, 1/2 + y, 3/2 − z), respectively.

2-bromo-6-chloro-4-nitroaniline top

Crystal data top

C₆H₄Br_0.90Cl_1.10N₂O₂	F(000) = 480.8
M_r = 247.02	D_x = 1.996 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1863 reflections
a = 3.8052 (3) Å	θ = 2.0–27.5°
b = 17.9667 (13) Å	µ = 4.83 mm⁻¹
c = 12.0417 (9) Å	T = 298 K
β = 93.224 (2)°	Plate, red
V = 821.95 (11) Å³	0.49 × 0.16 × 0.06 mm
Z = 4

Data collection top

Bruker SMART 1000 CCD area detector diffractometer	1863 independent reflections
Radiation source: Bruker-Nonius FR91 rotating anode	1357 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.037
ϕ–ω scans	θ_max = 27.5°, θ_min = 2.0°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −4→4
T_min = 0.201, T_max = 0.749	k = −23→16
5904 measured reflections	l = −15→15

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.087	H-atom parameters constrained
S = 1.02	w = 1/[σ²(F_o²) + (0.0477P)²] where P = (F_o² + 2F_c²)/3
1863 reflections	(Δ/σ)_max = 0.001
129 parameters	Δρ_max = 0.50 e Å⁻³
4 restraints	Δρ_min = −0.38 e Å⁻³

Crystal data top

C₆H₄Br_0.90Cl_1.10N₂O₂	V = 821.95 (11) Å³
M_r = 247.02	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 3.8052 (3) Å	µ = 4.83 mm⁻¹
b = 17.9667 (13) Å	T = 298 K
c = 12.0417 (9) Å	0.49 × 0.16 × 0.06 mm
β = 93.224 (2)°

Data collection top

Bruker SMART 1000 CCD area detector diffractometer	1863 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2000)	1357 reflections with I > 2σ(I)
T_min = 0.201, T_max = 0.749	R_int = 0.037
5904 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.040	4 restraints
wR(F²) = 0.087	H-atom parameters constrained
S = 1.02	Δρ_max = 0.50 e Å⁻³
1863 reflections	Δρ_min = −0.38 e Å⁻³
129 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Br2	0.1862 (12)	0.3784 (4)	0.4908 (2)	0.0367 (6)	0.50
Br6	0.832 (2)	0.2873 (4)	0.9060 (7)	0.0507 (11)	0.40
Cl2	0.152 (3)	0.3787 (11)	0.5097 (5)	0.0362 (14)	0.50
Cl6	0.778 (4)	0.2869 (5)	0.8918 (11)	0.0446 (12)	0.60
N1	0.4805 (8)	0.26991 (16)	0.6681 (3)	0.0545 (8)
N4	0.5273 (9)	0.56628 (18)	0.8132 (3)	0.0569 (8)
O41	0.3704 (10)	0.61269 (16)	0.7523 (3)	0.0789 (9)
O42	0.6807 (10)	0.58180 (18)	0.9026 (3)	0.0838 (10)
C1	0.4947 (8)	0.34078 (17)	0.7041 (3)	0.0370 (7)
C2	0.3633 (7)	0.40011 (17)	0.63759 (16)	0.0359 (7)
C3	0.3719 (8)	0.47309 (17)	0.6714 (3)	0.0383 (7)
C4	0.5183 (8)	0.48899 (19)	0.7769 (3)	0.0404 (8)
C5	0.6536 (8)	0.4335 (2)	0.8470 (3)	0.0427 (8)
C6	0.6380 (7)	0.36189 (15)	0.8095 (2)	0.0395 (8)
H1A	0.5584	0.2346	0.7111	0.065*
H1B	0.3883	0.2597	0.6031	0.065*
H3	0.2823	0.5108	0.6250	0.046*
H5	0.7519	0.4447	0.9175	0.051*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br2	0.0409 (11)	0.0396 (7)	0.0290 (9)	−0.0005 (9)	−0.0021 (10)	0.0000 (11)
Br6	0.037 (2)	0.0630 (12)	0.050 (2)	0.0040 (9)	−0.0141 (13)	0.0272 (11)
Cl2	0.0378 (19)	0.0454 (18)	0.026 (2)	−0.0016 (14)	0.0046 (18)	−0.003 (2)
Cl6	0.034 (3)	0.0550 (17)	0.042 (2)	0.0067 (15)	−0.0151 (18)	0.0203 (12)
N1	0.069 (2)	0.0347 (17)	0.059 (2)	0.0049 (14)	−0.0034 (17)	0.0026 (14)
N4	0.074 (2)	0.0446 (19)	0.053 (2)	−0.0122 (17)	0.0105 (17)	−0.0092 (16)
O41	0.117 (3)	0.0373 (18)	0.082 (2)	0.0081 (16)	−0.0024 (19)	−0.0034 (14)
O42	0.118 (3)	0.068 (2)	0.065 (2)	−0.0216 (19)	−0.0024 (18)	−0.0247 (16)
C1	0.0359 (16)	0.0319 (18)	0.0437 (19)	0.0020 (13)	0.0066 (14)	0.0042 (14)
C2	0.0302 (15)	0.0356 (17)	0.0419 (18)	−0.0013 (12)	0.0027 (13)	0.0016 (13)
C3	0.0368 (16)	0.0309 (17)	0.048 (2)	0.0003 (13)	0.0059 (14)	0.0058 (14)
C4	0.0426 (18)	0.0368 (19)	0.0423 (19)	−0.0037 (14)	0.0077 (14)	−0.0033 (15)
C5	0.0400 (17)	0.053 (2)	0.0351 (18)	−0.0077 (15)	0.0016 (14)	0.0019 (15)
C6	0.0326 (16)	0.0389 (19)	0.047 (2)	0.0010 (14)	0.0044 (14)	0.0117 (15)

Geometric parameters (Å, º) top

C1—C2	1.408 (4)	N4—O42	1.228 (4)
C2—C3	1.373 (4)	C2—Cl2	1.741 (2)
C3—C4	1.387 (5)	C2—Br2	1.8965 (19)
C4—C5	1.387 (5)	C3—H3	0.93
C5—C6	1.364 (5)	C5—H5	0.93
C6—C1	1.404 (5)	C6—Cl6	1.738 (2)
C1—N1	1.345 (4)	C6—Br6	1.8963 (19)
C4—N4	1.456 (5)	N1—H1A	0.86
N4—O41	1.241 (4)	N1—H1B	0.86

N1—C1—C6	123.6 (3)	C6—C5—C4	117.9 (3)
N1—C1—C2	121.8 (3)	C6—C5—H5	121.0
C6—C1—C2	114.6 (2)	C4—C5—H5	121.0
C3—C2—C1	123.5 (2)	C5—C6—C1	124.2 (2)
C3—C2—Cl2	118.4 (7)	C5—C6—Cl6	122.4 (6)
C1—C2—Cl2	117.9 (7)	C1—C6—Cl6	113.4 (5)
C3—C2—Br2	118.3 (3)	C5—C6—Br6	117.0 (4)
C1—C2—Br2	118.1 (3)	C1—C6—Br6	118.8 (4)
C2—C3—C4	118.0 (3)	C1—N1—H1A	119.9
C2—C3—H3	121.0	C1—N1—H1B	120.1
C4—C3—H3	121.0	H1A—N1—H1B	120.0
C5—C4—C3	121.7 (3)	O42—N4—O41	123.7 (4)
C5—C4—N4	120.1 (3)	O42—N4—C4	118.8 (4)
C3—C4—N4	118.2 (3)	O41—N4—C4	117.5 (3)

N1—C1—C2—C3	179.8 (3)	C4—C5—C6—C1	0.2 (5)
C6—C1—C2—C3	0.0 (4)	C4—C5—C6—Cl6	−176.7 (6)
N1—C1—C2—Cl2	4.4 (6)	C4—C5—C6—Br6	178.9 (4)
C6—C1—C2—Cl2	−175.4 (5)	N1—C1—C6—C5	−179.9 (3)
N1—C1—C2—Br2	−3.4 (5)	C2—C1—C6—C5	−0.1 (4)
C6—C1—C2—Br2	176.8 (3)	N1—C1—C6—Cl6	−2.7 (7)
C1—C2—C3—C4	0.0 (4)	C2—C1—C6—Cl6	177.1 (6)
Cl2—C2—C3—C4	175.4 (5)	N1—C1—C6—Br6	1.4 (6)
Br2—C2—C3—C4	−176.8 (3)	C2—C1—C6—Br6	−178.8 (4)
C2—C3—C4—C5	0.1 (4)	C5—C4—N4—O42	5.7 (5)
C2—C3—C4—N4	−179.9 (3)	C3—C4—N4—O42	−174.3 (3)
C3—C4—C5—C6	−0.2 (5)	C5—C4—N4—O41	−172.6 (3)
N4—C4—C5—C6	179.8 (3)	C3—C4—N4—O41	7.4 (5)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O41ⁱ	0.86	2.25	3.026 (4)	151

Symmetry code: (i) −x+1, y−1/2, −z+3/2.

Experimental details

Crystal data
Chemical formula	C₆H₄Br_0.90Cl_1.10N₂O₂
M_r	247.02
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	298
a, b, c (Å)	3.8052 (3), 17.9667 (13), 12.0417 (9)
β (°)	93.224 (2)
V (Å³)	821.95 (11)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	4.83
Crystal size (mm)	0.49 × 0.16 × 0.06

Data collection
Diffractometer	Bruker SMART 1000 CCD area detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2000)
T_min, T_max	0.201, 0.749
No. of measured, independent and observed [I > 2σ(I)] reflections	5904, 1863, 1357
R_int	0.037
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.040, 0.087, 1.02
No. of reflections	1863
No. of parameters	129
No. of restraints	4
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.50, −0.38

Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 2000), SAINT, OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997), OSCAIL and SHELXL97 (Sheldrick, 1997), PLATON (Spek, 2003), SHELXL97 and PRPKAPPA (Ferguson, 1999).

Selected bond lengths (Å) top

C1—C2	1.408 (4)	C6—C1	1.404 (5)
C2—C3	1.373 (4)	C1—N1	1.345 (4)
C3—C4	1.387 (5)	C4—N4	1.456 (5)
C4—C5	1.387 (5)	N4—O41	1.241 (4)
C5—C6	1.364 (5)	N4—O42	1.228 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O41ⁱ	0.86	2.25	3.026 (4)	151

Symmetry code: (i) −x+1, y−1/2, −z+3/2.

Acknowledgements

X-ray data were collected at the University of Aberdeen; the authors thank the university for funding the purchase of the diffractometer.

References

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ISSN: 2053-2296

Volume 61| Part 5| May 2005| Pages o336-o338

doi:10.1107/S0108270105010085

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organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Hydrogen bonding in C-substituted nitro­anilines: simple C(8) chains in 2-bromo-6-chloro-4-nitro­aniline

Comment

Experimental

Crystal data

Data collection

Refinement

Supporting information

Acknowledgements

References

organic compounds

Hydrogen bonding in C-substituted nitroanilines: simple C(8) chains in 2-bromo-6-chloro-4-nitroaniline