The study of inter­actions with a halogen atom: influence of NH₂ group insertion on the crystal structures of meta-bromo­nitro­benzene derivatives

Halogen atoms in mol­ecular crystals may be involved in various inter­actions, often playing a very important role in structure stabilization. By introducing electron-donating groups, such as NH₂, the electron density of the mol­ecule is changed and thus inter­actions with the bromine substituent may alter. Herein, the crystal structures of meta-bromo­nitro­benzene and its NH₂-substituted derivatives are analyzed. In all four described structures, namely m-bromo­nitro­benzene [Charlton & Trotter (1963). Acta Cryst. 16, 313], 4-bromo-2-nitro­aniline (C₆H₅BrN₂O₂, 1), 2-bromo-6-nitro­aniline (2) and 2-bromo-4-nitro­aniline [Arshad et al. (2009). Acta Cryst. E65, o480], the Br atom is engaged in different inter­actions (Br...π, Br...O, Br...Br and C—H...Br, respectively). The Hirshfeld surface analysis (HS) and Reduced Density Gradient NonCovalent Inter­action (RDG NCI) plots are used to prove the relevance, directionality and stabilizing nature of these inter­actions. Their modifications have been associated with the position of the amino group in the mol­ecular structure and its influence on charge distribution analyzed with electrostatic potential surfaces (EPS). The diversification of the inter­actions has been correlated with a σ-hole potential value that enables a switching of the Br-atom character from electrophilic to nucleophilic.

Computing details

For both structures, data collection: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015b); program(s) used to refine structure: SHELXL (Sheldrick, 2015a); molecular graphics: Mercury CSD (Macrae et al., 2008) and ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009) and publCIF (Westrip, 2010).

4-Bromo-2-nitroaniline (1)

Crystal data

C6H5BrN2O2	F(000) = 424
Mr = 217.03	Dx = 1.975 Mg m^−3
Monoclinic, Pc	Mo Kα radiation, λ = 0.71073 Å
a = 11.1643 (11) Å	Cell parameters from 3126 reflections
b = 3.8275 (4) Å	θ = 2.4–27.6°
c = 17.2764 (16) Å	µ = 5.58 mm^−1
β = 98.662 (3)°	T = 130 K
V = 729.82 (12) Å^3	Needle, yellow
Z = 4	0.60 × 0.42 × 0.38 mm

Data collection

Bruker D8 Venture Photon II diffractometer	2965 reflections with I > 2σ(I)
Radiation source: TRIUMPH monochromator and fine focus sealed tube	Rint = 0.059
φ and ω scans	θmax = 29.5°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −15→15
Tmin = 0.579, Tmax = 0.746	k = −5→5
12367 measured reflections	l = −23→20
3712 independent reflections

Refinement

Refinement on F^2	Hydrogen site location: mixed
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.041	w = 1/[σ^2(Fo^2)] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.080	(Δ/σ)max < 0.001
S = 1.02	Δρmax = 0.51 e Å^−3
3712 reflections	Δρmin = −0.77 e Å^−3
215 parameters	Absolute structure: Flack x determined using 1017 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
6 restraints	Absolute structure parameter: 0.030 (12)
Primary atom site location: dual

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.27039 (4)	0.95174 (18)	0.14819 (3)	0.0270 (2)
O1	0.1481 (4)	0.7273 (14)	0.4930 (3)	0.0280 (12)
O2	0.0525 (4)	1.0151 (13)	0.3946 (3)	0.0312 (12)
N1	0.3685 (7)	0.4902 (15)	0.4868 (4)	0.0277 (16)
H1A	0.313 (5)	0.521 (16)	0.518 (3)	0.018 (18)*
H1B	0.440 (3)	0.40 (2)	0.504 (5)	0.04 (2)*
N2	0.1407 (5)	0.8386 (15)	0.4244 (3)	0.0208 (12)
C1	0.3445 (6)	0.6017 (18)	0.4122 (4)	0.0196 (14)
C2	0.2357 (6)	0.7667 (18)	0.3791 (4)	0.0165 (13)
C3	0.2143 (6)	0.8733 (15)	0.3005 (3)	0.0143 (12)
H3	0.1404	0.9844	0.2797	0.017*
C4	0.3009 (6)	0.8151 (17)	0.2546 (4)	0.0192 (14)
C5	0.4104 (6)	0.6541 (18)	0.2851 (4)	0.0210 (15)
H5	0.4699	0.6126	0.2523	0.025*
C6	0.4319 (6)	0.5560 (18)	0.3623 (4)	0.0250 (15)
H6	0.5079	0.4547	0.3826	0.030*
Br11	0.77175 (6)	0.51283 (17)	0.85196 (4)	0.0268 (2)
O11	0.6691 (5)	1.1576 (16)	0.5080 (3)	0.0378 (14)
O12	0.5605 (4)	1.1624 (16)	0.6013 (3)	0.0387 (14)
N11	0.8927 (6)	0.9025 (18)	0.5326 (4)	0.0291 (14)
H11A	0.969 (2)	0.86 (2)	0.528 (5)	0.04 (2)*
H11B	0.837 (5)	1.016 (18)	0.501 (4)	0.04 (3)*
N12	0.6553 (5)	1.0795 (16)	0.5758 (4)	0.0254 (14)
C11	0.8602 (6)	0.8231 (17)	0.6033 (4)	0.0187 (14)
C12	0.7478 (6)	0.9009 (16)	0.6259 (4)	0.0172 (13)
C13	0.7217 (6)	0.8121 (17)	0.7007 (4)	0.0179 (14)
H13	0.6451	0.8691	0.7149	0.022*
C14	0.8055 (6)	0.6462 (16)	0.7522 (4)	0.0159 (13)
C15	0.9211 (6)	0.5656 (16)	0.7317 (4)	0.0196 (13)
H15	0.9808	0.4539	0.7684	0.024*
C16	0.9454 (6)	0.6492 (17)	0.6595 (4)	0.0199 (14)
H16	1.0223	0.5894	0.6460	0.024*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0404 (5)	0.0233 (3)	0.0199 (4)	0.0028 (4)	0.0134 (4)	0.0035 (4)
O1	0.029 (3)	0.043 (3)	0.012 (3)	0.003 (2)	0.007 (2)	0.004 (2)
O2	0.019 (2)	0.050 (4)	0.025 (3)	0.013 (2)	0.005 (2)	0.009 (2)
N1	0.030 (4)	0.029 (4)	0.020 (3)	0.009 (3)	−0.007 (3)	0.006 (3)
N2	0.014 (3)	0.031 (3)	0.017 (3)	−0.001 (2)	0.000 (2)	0.002 (2)
C1	0.015 (3)	0.016 (3)	0.025 (4)	0.002 (3)	−0.007 (3)	0.001 (3)
C2	0.015 (3)	0.022 (4)	0.013 (3)	−0.003 (3)	0.005 (2)	−0.001 (3)
C3	0.014 (3)	0.018 (3)	0.012 (3)	0.000 (2)	0.004 (3)	0.001 (2)
C4	0.021 (4)	0.020 (3)	0.018 (4)	−0.005 (3)	0.009 (3)	−0.003 (3)
C5	0.016 (3)	0.023 (4)	0.025 (4)	−0.002 (3)	0.008 (3)	−0.002 (3)
C6	0.013 (3)	0.028 (4)	0.032 (4)	0.004 (3)	0.000 (3)	−0.001 (3)
Br11	0.0406 (5)	0.0233 (3)	0.0179 (4)	−0.0007 (3)	0.0091 (3)	0.0024 (3)
O11	0.036 (3)	0.054 (4)	0.022 (3)	0.003 (3)	−0.001 (3)	0.015 (3)
O12	0.014 (3)	0.061 (4)	0.040 (3)	0.014 (2)	0.001 (2)	0.015 (3)
N11	0.030 (4)	0.042 (4)	0.018 (3)	−0.004 (3)	0.015 (3)	−0.001 (3)
N12	0.020 (3)	0.032 (3)	0.023 (3)	−0.001 (3)	−0.001 (3)	0.008 (3)
C11	0.020 (4)	0.018 (4)	0.020 (4)	0.001 (3)	0.009 (3)	−0.005 (3)
C12	0.016 (3)	0.019 (3)	0.018 (3)	0.001 (3)	0.005 (3)	−0.002 (2)
C13	0.015 (3)	0.019 (3)	0.022 (4)	−0.001 (3)	0.008 (3)	0.001 (3)
C14	0.020 (3)	0.016 (3)	0.013 (3)	−0.001 (3)	0.004 (3)	0.002 (2)
C15	0.016 (3)	0.021 (3)	0.020 (3)	0.004 (3)	−0.004 (3)	0.000 (3)
C16	0.013 (3)	0.023 (3)	0.025 (4)	0.003 (3)	0.005 (3)	−0.004 (3)

Geometric parameters (Å, º)

Br1—C4	1.892 (7)	Br11—C14	1.890 (6)
O1—N2	1.249 (6)	O11—N12	1.240 (8)
O2—N2	1.241 (7)	O12—N12	1.247 (7)
N1—H1A	0.879 (7)	N11—H11A	0.881 (7)
N1—H1B	0.879 (7)	N11—H11B	0.880 (7)
N1—C1	1.346 (10)	N11—C11	1.360 (9)
N2—C2	1.436 (8)	N12—C12	1.419 (9)
C1—C2	1.411 (9)	C11—C12	1.401 (9)
C1—C6	1.407 (10)	C11—C16	1.419 (9)
C2—C3	1.405 (8)	C12—C13	1.409 (9)
C3—H3	0.9500	C13—H13	0.9500
C3—C4	1.358 (8)	C13—C14	1.348 (9)
C4—C5	1.399 (9)	C14—C15	1.421 (9)
C5—H5	0.9500	C15—H15	0.9500
C5—C6	1.370 (10)	C15—C16	1.355 (9)
C6—H6	0.9500	C16—H16	0.9500
H1A—N1—H1B	122 (7)	H11A—N11—H11B	130 (8)
C1—N1—H1A	119 (5)	C11—N11—H11A	115 (5)
C1—N1—H1B	119 (6)	C11—N11—H11B	115 (6)
O1—N2—C2	120.2 (5)	O11—N12—O12	120.3 (6)
O2—N2—O1	120.9 (5)	O11—N12—C12	120.6 (6)
O2—N2—C2	118.9 (5)	O12—N12—C12	119.0 (6)
N1—C1—C2	124.3 (7)	N11—C11—C12	125.1 (6)
N1—C1—C6	119.4 (6)	N11—C11—C16	118.5 (6)
C6—C1—C2	116.3 (6)	C12—C11—C16	116.4 (6)
C1—C2—N2	121.8 (6)	C11—C12—N12	122.1 (6)
C3—C2—N2	116.1 (6)	C11—C12—C13	121.5 (6)
C3—C2—C1	122.1 (6)	C13—C12—N12	116.4 (5)
C2—C3—H3	120.5	C12—C13—H13	120.0
C4—C3—C2	119.1 (6)	C14—C13—C12	120.0 (6)
C4—C3—H3	120.5	C14—C13—H13	120.0
C3—C4—Br1	118.8 (5)	C13—C14—Br11	121.0 (5)
C3—C4—C5	120.7 (6)	C13—C14—C15	120.3 (6)
C5—C4—Br1	120.5 (5)	C15—C14—Br11	118.8 (5)
C4—C5—H5	119.9	C14—C15—H15	120.2
C6—C5—C4	120.2 (6)	C16—C15—C14	119.6 (6)
C6—C5—H5	119.9	C16—C15—H15	120.2
C1—C6—H6	119.2	C11—C16—H16	118.9
C5—C6—C1	121.7 (6)	C15—C16—C11	122.3 (6)
C5—C6—H6	119.2	C15—C16—H16	118.9
Br1—C4—C5—C6	179.9 (5)	Br11—C14—C15—C16	177.9 (5)
O1—N2—C2—C1	−6.5 (10)	O11—N12—C12—C11	3.7 (10)
O1—N2—C2—C3	174.2 (6)	O11—N12—C12—C13	−177.7 (6)
O2—N2—C2—C1	172.8 (6)	O12—N12—C12—C11	−175.1 (6)
O2—N2—C2—C3	−6.6 (9)	O12—N12—C12—C13	3.6 (9)
N1—C1—C2—N2	1.7 (11)	N11—C11—C12—N12	−0.8 (10)
N1—C1—C2—C3	−179.0 (6)	N11—C11—C12—C13	−179.4 (7)
N1—C1—C6—C5	177.7 (7)	N11—C11—C16—C15	178.9 (7)
N2—C2—C3—C4	179.5 (6)	N12—C12—C13—C14	−179.1 (6)
C1—C2—C3—C4	0.2 (10)	C11—C12—C13—C14	−0.5 (10)
C2—C1—C6—C5	−2.5 (10)	C12—C11—C16—C15	−0.8 (10)
C2—C3—C4—Br1	178.9 (5)	C12—C13—C14—Br11	−178.3 (5)
C2—C3—C4—C5	−0.5 (9)	C12—C13—C14—C15	1.1 (10)
C3—C4—C5—C6	−0.7 (10)	C13—C14—C15—C16	−1.6 (10)
C4—C5—C6—C1	2.2 (10)	C14—C15—C16—C11	1.4 (10)
C6—C1—C2—N2	−178.0 (6)	C16—C11—C12—N12	178.9 (6)
C6—C1—C2—C3	1.3 (10)	C16—C11—C12—C13	0.3 (9)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1	0.89 (6)	1.99 (6)	2.640 (9)	129 (4)
N1—H1B···O12^i	0.88 (5)	2.19 (7)	2.967 (9)	148 (6)
N11—H11A···O1^ii	0.88 (3)	2.23 (4)	3.104 (8)	169 (8)
N11—H11B···O11	0.88 (6)	1.97 (6)	2.655 (9)	134 (6)
N11—H11B···N12	0.88 (6)	2.58 (6)	2.939 (9)	106 (5)

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

2-Bromo-6-nitroaniline (2)

Crystal data

C6H5BrN2O2	F(000) = 424
Mr = 217.03	Dx = 2.055 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 4.4477 (2) Å	Cell parameters from 5872 reflections
b = 11.4469 (4) Å	θ = 2.3–30.4°
c = 13.8244 (5) Å	µ = 5.80 mm^−1
β = 94.635 (2)°	T = 130 K
V = 701.53 (5) Å^3	Needle, yellow
Z = 4	0.42 × 0.30 × 0.25 mm

Data collection

Bruker D8 Venture Photon II diffractometer	1813 reflections with I > 2σ(I)
φ and ω scans	Rint = 0.035
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	θmax = 30.6°, θmin = 2.3°
Tmin = 0.522, Tmax = 0.746	h = −6→6
14025 measured reflections	k = −16→16
2162 independent reflections	l = −16→19

Refinement

Refinement on F^2	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.023	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.050	w = 1/[σ^2(Fo^2) + (0.0164P)^2 + 0.5734P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max = 0.001
2162 reflections	Δρmax = 0.54 e Å^−3
108 parameters	Δρmin = −0.46 e Å^−3
2 restraints

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.23474 (4)	0.47820 (2)	0.10999 (2)	0.02263 (6)
O1	0.2381 (3)	0.58496 (13)	0.49773 (10)	0.0274 (3)
O2	0.5543 (3)	0.72679 (14)	0.52156 (10)	0.0321 (3)
N1	0.1533 (3)	0.48393 (15)	0.32640 (11)	0.0198 (3)
H1A	0.109 (6)	0.481 (2)	0.3871 (7)	0.034 (7)*
H1B	0.070 (5)	0.4381 (16)	0.2809 (12)	0.027 (6)*
N2	0.4252 (3)	0.65371 (14)	0.46827 (11)	0.0196 (3)
C1	0.3467 (4)	0.56763 (15)	0.30262 (12)	0.0150 (3)
C2	0.4908 (4)	0.64946 (15)	0.36741 (12)	0.0161 (3)
C3	0.6962 (4)	0.73235 (16)	0.33831 (14)	0.0195 (4)
H3	0.7920	0.7841	0.3849	0.023*
C4	0.7603 (4)	0.73946 (16)	0.24314 (14)	0.0208 (4)
H4	0.8998	0.7958	0.2234	0.025*
C5	0.6172 (4)	0.66259 (16)	0.17556 (13)	0.0198 (4)
H5	0.6557	0.6678	0.1091	0.024*
C6	0.4222 (4)	0.57999 (15)	0.20480 (12)	0.0164 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.02501 (10)	0.02499 (10)	0.01769 (9)	0.00115 (8)	0.00048 (6)	−0.00340 (7)
O1	0.0283 (7)	0.0344 (8)	0.0206 (7)	−0.0053 (6)	0.0092 (5)	0.0006 (6)
O2	0.0388 (8)	0.0336 (8)	0.0241 (7)	−0.0056 (7)	0.0041 (6)	−0.0109 (6)
N1	0.0213 (7)	0.0207 (7)	0.0177 (7)	−0.0036 (6)	0.0037 (6)	0.0007 (6)
N2	0.0195 (7)	0.0209 (8)	0.0185 (7)	0.0043 (6)	0.0020 (6)	−0.0010 (6)
C1	0.0126 (7)	0.0144 (8)	0.0180 (8)	0.0035 (6)	0.0016 (6)	0.0012 (6)
C2	0.0149 (7)	0.0173 (8)	0.0162 (8)	0.0036 (6)	0.0026 (6)	0.0010 (6)
C3	0.0160 (8)	0.0161 (8)	0.0261 (9)	0.0020 (7)	0.0008 (7)	0.0003 (7)
C4	0.0169 (8)	0.0186 (9)	0.0275 (9)	0.0012 (7)	0.0050 (7)	0.0044 (7)
C5	0.0183 (8)	0.0218 (9)	0.0199 (8)	0.0051 (7)	0.0061 (6)	0.0058 (7)
C6	0.0156 (8)	0.0181 (8)	0.0154 (8)	0.0040 (6)	0.0012 (6)	−0.0009 (6)

Geometric parameters (Å, º)

Br1—C6	1.8958 (17)	C1—C6	1.426 (2)
O1—N2	1.238 (2)	C2—C3	1.399 (2)
O2—N2	1.226 (2)	C3—H3	0.9500
N1—H1A	0.878 (5)	C3—C4	1.371 (3)
N1—H1B	0.878 (5)	C4—H4	0.9500
N1—C1	1.346 (2)	C4—C5	1.399 (3)
N2—C2	1.448 (2)	C5—H5	0.9500
C1—C2	1.413 (2)	C5—C6	1.366 (2)
H1A—N1—H1B	123 (2)	C2—C3—H3	119.8
C1—N1—H1A	117.3 (16)	C4—C3—C2	120.50 (17)
C1—N1—H1B	119.4 (15)	C4—C3—H3	119.8
O1—N2—C2	119.23 (15)	C3—C4—H4	120.5
O2—N2—O1	122.05 (16)	C3—C4—C5	119.02 (17)
O2—N2—C2	118.71 (15)	C5—C4—H4	120.5
N1—C1—C2	125.66 (16)	C4—C5—H5	119.9
N1—C1—C6	120.41 (16)	C6—C5—C4	120.22 (17)
C2—C1—C6	113.93 (15)	C6—C5—H5	119.9
C1—C2—N2	121.08 (15)	C1—C6—Br1	118.06 (13)
C3—C2—N2	116.17 (16)	C5—C6—Br1	118.36 (13)
C3—C2—C1	122.73 (16)	C5—C6—C1	123.56 (16)
O1—N2—C2—C1	−0.6 (2)	C1—C2—C3—C4	1.9 (3)
O1—N2—C2—C3	177.77 (16)	C2—C1—C6—Br1	−178.24 (12)
O2—N2—C2—C1	−179.49 (16)	C2—C1—C6—C5	0.4 (2)
O2—N2—C2—C3	−1.2 (2)	C2—C3—C4—C5	0.0 (3)
N1—C1—C2—N2	−3.6 (3)	C3—C4—C5—C6	−1.6 (3)
N1—C1—C2—C3	178.20 (16)	C4—C5—C6—Br1	179.99 (13)
N1—C1—C6—Br1	1.6 (2)	C4—C5—C6—C1	1.4 (3)
N1—C1—C6—C5	−179.78 (16)	C6—C1—C2—N2	176.23 (15)
N2—C2—C3—C4	−176.44 (16)	C6—C1—C2—C3	−2.0 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1	0.88 (1)	1.99 (2)	2.635 (2)	130 (2)
N1—H1A···O1^i	0.88 (1)	2.43 (2)	3.201 (2)	148 (2)
N1—H1B···Br1	0.88 (2)	2.57 (2)	3.0432 (15)	115 (2)
C3—H3···O2	0.95	2.33	2.661 (2)	100
C5—H5···O2^ii	0.95	2.53	3.253 (2)	133

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