3-Iodo­aniline

The title compound, C₆H₆IN, is the meta-iodinated derivative of aniline. The asymmetric unit contains two mol­ecules. The structure was refined as a two-component inversion twin with a volume ratio of 55.6:44.4. In the crystal, cooperative hydrogen bonds of the N–H⋯N type connect the mol­ecules into infinite chains propagating along the a-axis direction. Dispersive I⋯I contacts extend these chains to sheets perpendicular to the crystallographic c axis.

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Chemical scheme

Structure description

Aniline and its derivatives are valuable starting materials in synthetic organic chemistry and have found ample use in industrial processes, as is apparent in the historic establishment of the artificial dye and, subsequently, pharmaceutical industry (Griess, 1879; Bopp et al., 1891). As an activated aromatic system, a large number of reactions is available for further functionalization of the phenyl group as well as the ipso-substitution of the amine functionality itself (Becker et al., 2000; Sandmeyer, 1884), which allows for tailoring the physicochemical and spectroscopic properties of the target mol­ecules over a seemingly endless range. In a continuation of our own inter­est in the structural variety of aniline derivatives (Islor et al., 2013; Betz & Gerber, 2011; Betz et al., 2008, 2011a,b; Betz, 2015; Hosten & Betz, 2021a,b,c) as well as pyridine-based amines (Betz et al., 2011c,d) we sought to determine the structure of 3-iodo­aniline. Structural information about this mol­ecule is scarce as only protonated versions of the compound under investigation are apparent in the literature, such as the chloride (Xing et al., 2021), iodide (Gray & Jones, 2002), phosphate (Yoshii et al., 2015), ortho-nitro­phthalate (Glidewell et al., 2005) as well as the crown-ether-supported salts of an anionic nickel coordination compound (Kubo et al., 2021) and two Keggin-ion-inspired polyoxometallates derived from molybdenum (Xiong et al., 2015, 2016), with a metal–organic molybdenum coordination compound being the only example in which structural data about the neutral title compound – as a ligand – is available (Xing et al., 2021).

The title compound is the meta-iodinated derivative of aniline. The asymmetric unit contains two mol­ecules. The structure was refined as an inversion twin with a volume ratio of 55.6:44.4. The C—I bond lengths of 2.105 (10) and 2.113 (11) Å are in good agreement with other aromatic iodine compounds whose metrical parameters have been determined on the basis of diffraction studies on single crystals and whose metrical parameters have been deposited with the Cambridge Structural Database (Groom et al., 2016). The intra­cyclic C—C—C angles span a range of 117.9 (11)–122.4 (11)° in the first and 117.9 (9)–122.5 (10)° in the second mol­ecule present in the asymmetric unit with the smallest angle on the carbon atom in para-position to the amino group in the first mol­ecule and in ortho-position to the amino group in the second mol­ecule. The largest C—C—C angle is invariably found on the carbon atom bearing the halogen substituent. The least-squares planes as defined by the carbon atoms of the two respective aromatic systems enclose an angle of 83.3 (5)° (Fig. 1).

Figure 1 The mol­ecular structure of the title compound, with atom labels and anisotropic displacement ellipsoids (drawn at the 50% probability level).

In the crystal, cooperative hydrogen bonds of the N—H⋯N type (Table 1) are apparent that are supported by only one hydrogen in each amino group. These connect the mol­ecules into infinite chains propagating along the a-axis direction. In terms of graph-set analysis (Etter et al., 1990; Bernstein et al., 1995), the descriptor for these hydrogen bonds is DD on the unary level. Furthermore, dispersive I⋯I contacts are observed whose range of 3.79 (1)–3.85 (1) Å falls by more than 0.1 Å below the sum of the van der Waals radii of the atoms participating in them. The latter extend the chains to sheets lying perpendicular to the crystallographic c axis. π-Stacking is not a prominent stabilizing feature in the crystal structure of the title compound with the shortest inter­centroid distance measured at 5.074 (6) Å between the aromatic system of one of the two mol­ecules present in the asymmetric unit and its symmetry-generated equivalent, which corresponds to the b-axis unit-cell dimension (Fig. 2).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H711⋯N2	0.78 (15)	2.38 (16)	3.156 (17)	170 (15)
N2—H722⋯N1^i	0.84 (15)	2.33 (15)	3.157 (18)	171 (13)
C13—I1⋯I2^ii	2.11 (1)	3.85 (1)	8.677 (10)	173 (1)
C23—I2⋯I1^iii	2.11 (1)	3.79 (1)	9.437 (9)	172 (1)
Symmetry codes: (i) ; (ii) ; (iii) .

Figure 2 Inter­molecular contacts, viewed along [001].

Synthesis and crystallization

The title compound was obtained commercially (Sigma-Aldrich). A crystal suitable for the diffraction study was obtained upon prolonged and repeated sublimation and re-sublimation of the compound at a temperature just above 0°C in a fridge.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C6H6IN
Mr	219.02
Crystal system, space group	Orthorhombic, P212121
Temperature (K)	200
a, b, c (Å)	5.0748 (3), 12.9872 (8), 20.6243 (12)
V (Å^3)	1359.29 (14)
Z	8
Radiation type	Mo Kα
μ (mm^−1)	4.60
Crystal size (mm)	0.30 × 0.29 × 0.22
Data collection
Diffractometer	Bruker D8 Quest
Absorption correction	Multi-scan (SADABS; Krause et al., 2015)
Tmin, Tmax	0.280, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	3508, 3379, 3094
Rint	0.025
(sin θ/λ)max (Å^−1)	0.667
Refinement
R[F^2 > 2σ(F^2)], wR(F^2), S	0.048, 0.079, 1.25
No. of reflections	3379
No. of parameters	158
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å^−3)	0.96, −1.04
Absolute structure	Refined as an inversion twin
Absolute structure parameter	0.44 (9)
Computer programs: APEX2 and SAINT (Bruker, 2014), SHELXS97 (Sheldrick 2008), ORTEP-3 for Windows (Farrugia, 2012), Mercury (Macrae et al., 2020), SHELXL2019/3 (Sheldrick, 2015) and PLATON (Spek, 2020).

Structural data

Computing details

3-Iodoaniline

Crystal data

C6H6IN	Dx = 2.140 Mg m^−3
Mr = 219.02	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121	Cell parameters from 9179 reflections
a = 5.0748 (3) Å	θ = 2.5–28.3°
b = 12.9872 (8) Å	µ = 4.60 mm^−1
c = 20.6243 (12) Å	T = 200 K
V = 1359.29 (14) Å^3	Block, colourless
Z = 8	0.30 × 0.29 × 0.22 mm
F(000) = 816

Data collection

Bruker D8 Quest diffractometer	3094 reflections with I > 2σ(I)
φ and ω scans	Rint = 0.025
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	θmax = 28.3°, θmin = 2.5°
Tmin = 0.280, Tmax = 0.746	h = −6→6
3508 measured reflections	k = 0→17
3379 independent reflections	l = 0→27

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.048	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.079	w = 1/[σ^2(Fo^2) + 10.4557P] where P = (Fo^2 + 2Fc^2)/3
S = 1.25	(Δ/σ)max < 0.001
3379 reflections	Δρmax = 0.96 e Å^−3
158 parameters	Δρmin = −1.04 e Å^−3
0 restraints	Absolute structure: Refined as an inversion twin
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.44 (9)

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.

Refinement. Refined as a 2-component inversion twin. The aromatic carbon-bound H atoms were placed in calculated positions (C–H 0.95 Å) and were included in the refinement in the riding model approximation, with U(H) set to 1.2U_eq(C). The N–H bonded H atoms were located on a DFM and included in the refinement with with U(H) set to 1.5U_eq(N).

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

	x	y	z	Uiso*/Ueq
I1	−0.29954 (15)	0.23185 (5)	0.36694 (4)	0.03054 (16)
I2	0.19029 (13)	1.01208 (5)	0.36477 (4)	0.03011 (16)
N1	0.311 (2)	0.5517 (8)	0.2859 (5)	0.038 (2)
H711	0.45 (3)	0.581 (12)	0.283 (7)	0.057*
H712	0.29 (3)	0.523 (10)	0.246 (6)	0.057*
N2	0.811 (2)	0.6961 (7)	0.2824 (5)	0.035 (2)
H721	0.79 (3)	0.718 (10)	0.244 (6)	0.053*
H722	0.95 (3)	0.660 (12)	0.288 (7)	0.053*
C11	0.246 (2)	0.4856 (8)	0.3367 (5)	0.034 (3)
C12	0.055 (2)	0.4098 (8)	0.3286 (5)	0.027 (2)
H12	−0.025586	0.399800	0.287462	0.033*
C13	−0.017 (2)	0.3494 (8)	0.3806 (5)	0.028 (2)
C14	0.096 (2)	0.3604 (10)	0.4415 (5)	0.037 (3)
H14	0.044405	0.317533	0.476599	0.044*
C15	0.285 (3)	0.4353 (9)	0.4494 (5)	0.040 (3)
H15	0.365993	0.444220	0.490503	0.048*
C16	0.359 (2)	0.4986 (9)	0.3974 (5)	0.035 (3)
H16	0.487506	0.550785	0.403765	0.042*
C21	0.7402 (19)	0.7588 (8)	0.3351 (5)	0.029 (2)
C22	0.548 (2)	0.8356 (8)	0.3249 (5)	0.027 (2)
H22	0.474817	0.847272	0.283107	0.032*
C23	0.4677 (17)	0.8935 (7)	0.3780 (5)	0.023 (2)
C24	0.568 (2)	0.8779 (8)	0.4395 (5)	0.032 (2)
H24	0.507738	0.917882	0.475135	0.038*
C25	0.757 (2)	0.8032 (8)	0.4478 (5)	0.035 (3)
H25	0.827830	0.792069	0.489853	0.042*
C26	0.846 (2)	0.7436 (9)	0.3964 (5)	0.032 (3)
H26	0.977570	0.692867	0.403175	0.039*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.0283 (3)	0.0277 (3)	0.0356 (3)	0.0017 (3)	0.0044 (4)	0.0022 (3)
I2	0.0273 (3)	0.0253 (3)	0.0377 (3)	0.0014 (3)	0.0022 (4)	0.0021 (3)
N1	0.029 (5)	0.036 (5)	0.049 (6)	−0.011 (5)	0.004 (5)	0.004 (4)
N2	0.043 (6)	0.026 (5)	0.037 (5)	0.002 (5)	0.004 (5)	−0.004 (4)
C11	0.027 (7)	0.026 (5)	0.049 (6)	0.004 (5)	−0.005 (5)	−0.005 (5)
C12	0.029 (6)	0.032 (6)	0.021 (5)	0.003 (5)	−0.003 (4)	−0.001 (4)
C13	0.025 (5)	0.028 (5)	0.032 (6)	0.001 (4)	−0.002 (4)	−0.001 (4)
C14	0.038 (7)	0.046 (7)	0.027 (5)	0.007 (6)	0.002 (5)	0.002 (5)
C15	0.041 (7)	0.048 (7)	0.031 (5)	0.007 (6)	−0.012 (5)	−0.010 (5)
C16	0.030 (6)	0.032 (6)	0.043 (6)	−0.014 (5)	0.006 (5)	−0.015 (5)
C21	0.015 (6)	0.036 (6)	0.036 (5)	−0.013 (5)	−0.002 (4)	0.006 (4)
C22	0.025 (6)	0.028 (5)	0.027 (5)	−0.002 (5)	−0.010 (4)	0.006 (4)
C23	0.012 (4)	0.023 (5)	0.033 (5)	−0.004 (4)	0.005 (4)	0.002 (4)
C24	0.038 (6)	0.032 (6)	0.024 (5)	0.000 (5)	0.005 (5)	−0.001 (4)
C25	0.040 (8)	0.038 (6)	0.028 (5)	−0.002 (5)	0.000 (5)	0.004 (4)
C26	0.023 (6)	0.036 (6)	0.037 (5)	−0.003 (5)	−0.005 (5)	0.013 (5)

Geometric parameters (Å, º)

I1—C13	2.113 (11)	C14—H14	0.9500
I2—C23	2.105 (10)	C15—C16	1.403 (16)
N1—C11	1.394 (14)	C15—H15	0.9500
N1—H711	0.78 (15)	C16—H16	0.9500
N1—H712	0.92 (13)	C21—C26	1.388 (13)
N2—C21	1.404 (14)	C21—C22	1.412 (15)
N2—H721	0.84 (13)	C22—C23	1.388 (14)
N2—H722	0.84 (15)	C22—H22	0.9500
C11—C16	1.388 (14)	C23—C24	1.381 (14)
C11—C12	1.391 (15)	C24—C25	1.374 (16)
C12—C13	1.378 (14)	C24—H24	0.9500
C12—H12	0.9500	C25—C26	1.389 (15)
C13—C14	1.388 (15)	C25—H25	0.9500
C14—C15	1.375 (17)	C26—H26	0.9500
C11—N1—H711	124 (10)	C11—C16—C15	120.5 (10)
C11—N1—H712	113 (8)	C11—C16—H16	119.8
H711—N1—H712	105 (10)	C15—C16—H16	119.8
C21—N2—H721	120 (9)	C26—C21—N2	121.6 (10)
C21—N2—H722	116 (10)	C26—C21—C22	120.2 (10)
H721—N2—H722	114 (10)	N2—C21—C22	118.2 (10)
C16—C11—C12	118.9 (10)	C23—C22—C21	117.9 (9)
C16—C11—N1	120.2 (10)	C23—C22—H22	121.1
C12—C11—N1	120.7 (10)	C21—C22—H22	121.1
C13—C12—C11	119.6 (10)	C24—C23—C22	122.5 (10)
C13—C12—H12	120.2	C24—C23—I2	118.2 (8)
C11—C12—H12	120.2	C22—C23—I2	119.3 (7)
C12—C13—C14	122.4 (11)	C25—C24—C23	118.3 (10)
C12—C13—I1	119.2 (8)	C25—C24—H24	120.8
C14—C13—I1	118.3 (8)	C23—C24—H24	120.8
C15—C14—C13	117.9 (11)	C24—C25—C26	121.6 (10)
C15—C14—H14	121.1	C24—C25—H25	119.2
C13—C14—H14	121.1	C26—C25—H25	119.2
C14—C15—C16	120.7 (10)	C21—C26—C25	119.5 (10)
C14—C15—H15	119.6	C21—C26—H26	120.3
C16—C15—H15	119.6	C25—C26—H26	120.3
C16—C11—C12—C13	−0.2 (16)	C26—C21—C22—C23	−0.6 (15)
N1—C11—C12—C13	−176.3 (10)	N2—C21—C22—C23	176.5 (10)
C11—C12—C13—C14	−0.6 (17)	C21—C22—C23—C24	−0.5 (15)
C11—C12—C13—I1	−178.3 (8)	C21—C22—C23—I2	178.0 (7)
C12—C13—C14—C15	0.5 (17)	C22—C23—C24—C25	1.0 (16)
I1—C13—C14—C15	178.2 (8)	I2—C23—C24—C25	−177.5 (8)
C13—C14—C15—C16	0.3 (17)	C23—C24—C25—C26	−0.4 (17)
C12—C11—C16—C15	1.0 (17)	N2—C21—C26—C25	−175.8 (10)
N1—C11—C16—C15	177.1 (11)	C22—C21—C26—C25	1.1 (16)
C14—C15—C16—C11	−1.1 (18)	C24—C25—C26—C21	−0.7 (17)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H711···N2	0.78 (15)	2.38 (16)	3.156 (17)	170 (15)
N2—H722···N1^i	0.84 (15)	2.33 (15)	3.157 (18)	171 (13)
C13—I1···I2^ii	2.11 (1)	3.85 (1)	8.677 (10)	173 (1)
C23—I2···I1^iii	2.11 (1)	3.79 (1)	9.437 (9)	172 (1)

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