2-Iodo­aniline at 100 K

Parkin, A.; Spanswick, C.K.; Pulham, C.R.; Wilson, C.C.

doi:10.1107/S1600536805007038

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 61| Part 4| April 2005| Pages o1087-o1089

https://doi.org/10.1107/S1600536805007038

2-Iodoaniline at 100 K

Andrew Parkin,^a ^* Christopher K. Spanswick,^b Colin R. Pulham ^b and Chick C. Wilson ^a

^aDepartment of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland, and ^bSchool of Chemistry, University of Edinburgh, Joseph Black Building, West Mains Road, Edinburgh EH9 3JJ, Scotland
^*Correspondence e-mail: a.parkin@chem.gla.ac.uk

(Received 3 February 2005; accepted 7 March 2005; online 25 March 2005)

In the crystal structure of the title compound, C₆H₆IN, each 2-iodoaniline molecule forms part of three extended helices. Each helix exhibits a different intermolecular interaction, viz. weak N—H⋯N hydrogen bonds with an H⋯N distance of 2.31 (11) Å, I⋯I interactions of 3.7986 (15) Å and C—H⋯π contact distances of 2.53 Å.

Comment

Despite their simple structure and ready availability, few crystal structures of molecular complexes involving 2-haloanilines have been previously determined, with only eight examples in version 5.25 of the Cambridge Structural Database (CSD; Allen, 2002 ). In addition, the molecular structure of 2-fluoroaniline has been investigated by gas-phase electron diffraction (Csákvái & Hargittai, 1992 ). Four of these crystal structures contain 2-iodoaniline or the protonated 2-iodoanilinium cation. In one study (CSD refcode ZOJYAY; Casas et al., 1996 ), the iodoaniline acts as a chelating ligand to a Pt metal centre (coordinated through the N and I atoms), whereas in the other three, the iodoaniline is in protonated ionic complexes, one as the halide salt, 2-iodoanilinium iodide (CSD refcode UFAJIU; Gray & Jones, 2002 ), and perhaps most notably in two polymorphs of 2-iodoanilinium picrate (CSD refcodes ZEDPON and ZEDPON01; Tanaka et al., 1994 ). The structure of the title compound, (I), presented in this paper is thus the first example to be published of a crystal structure of the non-coordinated neutral compound, a fact that can probably be attributed to the low melting points of this family of materials (2-iodoaniline melts just above room temperature).

The geometry of the amino N atom (N1) in the crystal structure of (I) is observed to be slightly pyramidal in character (Fig. 1), with the sum of the angles around N1 equal to about 347°, similar to the value observed in the gas-phase electron diffraction structure of 2-fluoroaniline (Csákvái & Hargittai, 1992). Although there is obviously a large uncertainty in these values because of the presence of the I atom, the non-planarity of N1 is reasonable in terms of the hydrogen-bonding network observed within the crystal structure. The amino groups form a hydrogen-bonded chain, with an N1⋯N1ⁱ separation of 3.161 (14) Å, an H11⋯N1ⁱ distance of 2.31 (11) Å and an N1—H11⋯N1ⁱ angle of 157 (10)° [symmetry code: (i) 1 − x + y, −x, $[{1\over 3}]$ + z]. Although this is a rather weak interaction, it is comparable with the similar hydrogen bond that is observed in 2,4-dibromo-6-chloroaniline (Ferguson et al., 1998 ), where the N⋯N distance is 3.150 (11) Å.

Overall, the crystal packing of (I) can be described in terms of three distinct helices (Fig. 2), one kept together via these weak N—H⋯N hydrogen bonds, another involving I⋯I interactions and the third formed by C—H⋯π interactions. Each molecule in the structure is involved in all three types of helices (Fig. 2). The I atoms form an infinite chain via I1⋯I1ⁱⁱ interactions, with an I1⋯I1ⁱⁱ distance of 3.7986 (15) Å [symmetry code: (ii) −y, x−y, − $[{1\over 3}]$ + z]. These interactions are similar to those reported by Gray & Jones (2002) in their structure of 3-iodoanilinium iodide, containing two crystallographically unique I⋯I interactions with I⋯I distances of 3.7820 (6) and 3.9241 (6) Å. The third helix of C—H⋯π interactions involves the C5—H51 bond oriented in the approximate direction of the C3—H31 bond in the molecule related by symmetry position (1 − y, x−y, − $[{1\over 3}]$ + z), with H51⋯H31 and H51⋯C3 distances of 2.53 and 2.86 Å, respectively.

Figure 1
A view of (I)

, showing the atomic numbering scheme. Ellipsoids are drawn at the 50% probability level.

Figure 2
Packing diagrams for (I)

, viewed down the c axis. The three helices observed in the crystal packing are indicated on the left, with the weak amine–amine hydrogen bond highlighted in blue, the I⋯I contacts in white and the C—H⋯π interactions in yellow.

Experimental

2-Iodoaniline (98%) was obtained from Aldrich. A quantity (0.4 g) of the compound was purified by recrystallization from benzene. Colourless needle crystals of (I) were grown by heating the solution until all the precipitated material was redissolved, and then allowing the solution to cool slowly to room temperature.

Crystal data

C₆H₆IN
M_r = 219.02
Trigonal, P 3₂
a = 11.2952 (8) Å
c = 4.5325 (4) Å
V = 500.79 (7) Å³
Z = 3
D_x = 2.179 Mg m⁻³
Mo Kα radiation
Cell parameters from 4867 reflections
θ = 0–32°
μ = 4.69 mm⁻¹
T = 100 K
Needle, colourless
0.50 × 0.10 × 0.10 mm

Data collection

Nonius KappaCCD area-detector diffractometer
φ and ω scans
Absorption correction: multi-scan(MULABS in PLATON; Spek, 1998 )T_min = 0.385, T_max = 0.626
4867 measured reflections
2174 independent reflections
1959 reflections with I > 2σ(I)
R_int = 0.104
θ_max = 31.9°
h = −16 → 16
k = −16 → 15
l = −6 → 6

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.048
wR(F²) = 0.124
S = 1.00
2174 reflections
80 parameters
H atoms treated by a mixture of independent and constrained refinement
w = 1/[σ²(F²) + 0.07 + 1.39P] where P = [max(F_o²,0) + 2F_c²]/3
(Δ/σ)_max < 0.001
Δρ_max = 1.4 e Å⁻³
Δρ_min = −2.0 e Å⁻³
Extinction correction: none
Absolute structure: Flack (1983 ), 1032 Friedel pairs
Flack parameter: 0.03 (8)

Table 1
Selected geometric parameters (Å, °)

N1—C1	1.401 (11)
I1—C2	2.103 (7)
C1—C2	1.400 (11)
C1—C6	1.419 (11)
C2—C3	1.413 (11)
C3—C4	1.406 (13)
C4—C5	1.384 (15)
C5—C6	1.390 (13)

N1—C1—C2	122.5 (7)
N1—C1—C6	119.4 (7)
C2—C1—C6	118.0 (7)
C1—C2—I1	119.9 (6)
C1—C2—C3	121.1 (7)
I1—C2—C3	119.0 (6)
C2—C3—C4	119.8 (8)
C3—C4—C5	119.0 (8)
C4—C5—C6	121.7 (8)
C1—C6—C5	120.3 (8)

All H atoms were positioned geometrically. Those bound to C atoms were refined as riding groups, while those bound to N atoms were refined, with the N—H bond length restrained to 0.90 (1) Å. Although the value of R_int is rather high for this structure (0.104), as are the minimum and maximum difference densities The positions of the minimum and maximum difference electron densities are at (0.806, 0.861, 0.167) and (0.407, 0.280, -0.008), respectively.

Data collection: COLLECT (Nonius, 2001 ); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997 ); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003 ); molecular graphics: ORTEP3 (Farrugia, 1997 ) and MERCURY (Version 1.3; Bruno et al., 2002 ); software used to prepare material for publication: CRYSTALS.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536805007038/ya6240sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536805007038/ya6240Isup2.hkl

Computing details top

Data collection: COLLECT (Nonius, 2001); cell refinement: DENZO and SCALEPACK; data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Version 1.3; Bruno et al., 2002); software used to prepare material for publication: CRYSTALS.

2-Iodoaniline top

Crystal data top

C₆H₆IN	D_x = 2.179 Mg m⁻³
M_r = 219.02	Mo Kα radiation, λ = 0.71073 Å
Trigonal, P3₂	Cell parameters from 16755 reflections
Hall symbol: P 32	θ = 0–32°
a = 11.2952 (8) Å	µ = 4.69 mm⁻¹
c = 4.5325 (4) Å	T = 100 K
V = 500.79 (7) Å³	Needle, colourless
Z = 3	0.50 × 0.10 × 0.10 mm
F(000) = 306

Data collection top

Nonius KappaCCD area-detector diffractometer	1959 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.104
φ and ω scans	θ_max = 31.9°, θ_min = 2.1°
Absorption correction: multi-scan (MULABS in PLATON; Spek, 1998)	h = −16→16
T_min = 0.385, T_max = 0.626	k = −16→15
4867 measured reflections	l = −6→6
2174 independent reflections

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F² > 2σ(F²)] = 0.048	w = 1/[σ²(F²) + 0.07 + 1.39p] where p = [max(F_o²,0) + 2F_c²]/3
wR(F²) = 0.124	(Δ/σ)_max < 0.001
S = 1.00	Δρ_max = 1.4 e Å⁻³
2174 reflections	Δρ_min = −2.0 e Å⁻³
80 parameters	Absolute structure: Flack (1983), 1032 Friedel pairs
3 restraints	Absolute structure parameter: 0.03 (8)
Primary atom site location: structure-invariant direct methods

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

	x	y	z	U_iso*/U_eq
N1	0.3281 (7)	−0.1940 (7)	0.8337 (15)	0.0237
I1	0.13684 (5)	−0.06459 (5)	0.6472 (5)	0.0232
C1	0.3972 (8)	−0.0834 (8)	0.6404 (15)	0.0209
C2	0.3350 (8)	−0.0147 (8)	0.5157 (17)	0.0216
C3	0.4047 (9)	0.0911 (8)	0.3077 (16)	0.0260
C4	0.5396 (9)	0.1303 (9)	0.2276 (19)	0.0297
C5	0.6015 (9)	0.0634 (10)	0.354 (2)	0.0317
C6	0.5335 (8)	−0.0418 (8)	0.5565 (18)	0.0252
H11	0.392 (9)	−0.211 (12)	0.91 (3)	0.0294*
H12	0.261 (9)	−0.195 (12)	0.94 (2)	0.0294*
H31	0.3585	0.1382	0.2174	0.0319*
H41	0.5904	0.2055	0.0817	0.0352*
H51	0.6979	0.0917	0.2993	0.0409*
H61	0.5808	−0.0885	0.6432	0.0314*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.022 (3)	0.026 (3)	0.024 (3)	0.012 (3)	−0.001 (2)	0.002 (2)
I1	0.0221 (2)	0.0236 (2)	0.0265 (2)	0.01328 (19)	0.00161 (18)	0.00084 (18)
C1	0.023 (3)	0.021 (3)	0.020 (3)	0.012 (3)	−0.001 (2)	−0.007 (2)
C2	0.021 (3)	0.023 (3)	0.024 (3)	0.013 (3)	0.003 (3)	−0.003 (3)
C3	0.033 (4)	0.020 (3)	0.023 (4)	0.012 (3)	−0.001 (3)	−0.003 (3)
C4	0.030 (4)	0.026 (4)	0.025 (4)	0.008 (3)	0.008 (3)	−0.002 (3)
C5	0.024 (4)	0.035 (4)	0.034 (4)	0.013 (3)	0.006 (3)	−0.008 (3)
C6	0.021 (3)	0.024 (3)	0.029 (4)	0.010 (3)	0.000 (3)	−0.007 (3)

Geometric parameters (Å, º) top

N1—C1	1.401 (11)	C3—C4	1.406 (13)
N1—H11	0.90 (5)	C3—H31	1.000
N1—H12	0.89 (5)	C4—C5	1.384 (15)
I1—C2	2.103 (7)	C4—H41	1.000
C1—C2	1.400 (11)	C5—C6	1.390 (13)
C1—C6	1.419 (11)	C5—H51	1.000
C2—C3	1.413 (11)	C6—H61	1.000

C1—N1—H11	106 (8)	C4—C3—H31	119.938
C1—N1—H12	116 (7)	C3—C4—C5	119.0 (8)
H11—N1—H12	124 (11)	C3—C4—H41	120.571
N1—C1—C2	122.5 (7)	C5—C4—H41	120.401
N1—C1—C6	119.4 (7)	C4—C5—C6	121.7 (8)
C2—C1—C6	118.0 (7)	C4—C5—H51	119.318
C1—C2—I1	119.9 (6)	C6—C5—H51	118.950
C1—C2—C3	121.1 (7)	C1—C6—C5	120.3 (8)
I1—C2—C3	119.0 (6)	C1—C6—H61	119.835
C2—C3—C4	119.8 (8)	C5—C6—H61	119.860
C2—C3—H31	120.298

Acknowledgements

This work was supported by the EPSRC through grants GR/T1608 and GR/T21615. We also acknowledge the CCLRC for support for CKS.

References

Allen, F. H. (2002). Acta Cryst. B58, 380–388. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Altomare, A., Cascarano, G., Giacovazzo G., Guagliardi A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435. CrossRef IUCr Journals Google Scholar
Betteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487. Web of Science CrossRef IUCr Journals Google Scholar
Bruno, I. J., Cole, J. C., Edgington, P. R., Kessler, M. K., Macrae, C. F., McCabe, P., Pearson, J. & Taylor, R. (2002). Acta Cryst. B58, 389–397. Web of Science CrossRef CAS IUCr Journals Google Scholar
Casas, J. M., Falvello, L. R., Fornies, J. & Martin, A. (1996). Inorg. Chem. 35, 56–62. CrossRef PubMed CAS Google Scholar
Csákvái, E. & Hargittai, I. (1992). J. Phys. Chem. 96, 5837–5842. CrossRef Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Ferguson, G., Low, J. N., Penner, G. H. & Wardell, J. L. (1998). Acta Cryst. C54, 1974–1977. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Flack H. D. (1983). Acta Cryst. A39, 876–881. CrossRef IUCr Journals Google Scholar
Gray, L. & Jones, P. G. (2002). Z. Naturforsch. Teil B, 57, 61–72. CAS Google Scholar
Nonius (2001). COLLECT. Nonius BV, Delft, The Netherlands. Google Scholar
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press. Google Scholar
Spek, A. L. (1998) PLATON. University of Utrecht, The Netherlands. Google Scholar
Tanaka, M., Matsui, H., Mizoguchi, J. & Kashino, S. (1994). Bull. Chem. Soc. Jpn, 67, 1572–1579. CAS Google Scholar

© International Union of Crystallography. Prior permission is not required to reproduce short quotations, tables and figures from this article, provided the original authors and source are cited. For more information, click here.