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Journal logoSTRUCTURAL
CHEMISTRY
ISSN: 2053-2296

Hydro­gen bonding in substituted nitro­anilines: hydrogen-bonded sheets in 4-iodo-3-nitro­aniline

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

(Received 3 March 2004; accepted 15 March 2004; online 9 April 2004)

In the title compound, C6H5IN2O2, the nitro group is disordered over two sets of sites, each with 0.5 occupancy, and the amino N atom is pyramidal. The mol­ecules are linked into sheets by a combination of three-centre N—H⋯(O)2 hydrogen bonds involving alternative pairs of O-atom sites and two-centre N—H⋯N hydrogen bonds involving the pyramidal amino group.

Comment

We have recently reported the molecular and supramolecular structures of a number of iodonitro­anilines, no two of which exhibit in their supramolecular structures the same pattern of N—H⋯O hydrogen bonds, iodo–nitro interactions or aromatic ππ stacking interactions (Garden, Glidewell et al., 2001[Garden, S. J., Glidewell, C., Low, J. N., McWilliam, S. A., Pinto, A. C., Skakle, J. M. S., Torres, J. C. & Wardell, J. L. (2001). Acta Cryst. C57, 1212-1214.]; McWilliam et al., 2001[McWilliam, S. A., Skakle, J. M. S., Low, J. N., Wardell, J. L., Garden, S. J., Pinto, A. C., Torres, J. C. & Glidewell, C. (2001). Acta Cryst. C57, 942-945.], Garden et al., 2002[Garden, S. J., Fontes, S. P., Wardell, J. L., Skakle, J. M. S., Low, J. N. & Glidewell, C. (2002). Acta Cryst. B58, 701-709.]).

Iodination of 3-nitro­aniline using a solution of K[ICl2] in methanol as the iodinating agent (Larsen et al., 1956[Larsen, A. A., Moore, C., Sprague, J., Cloke, B., Moss, J. & Hoppe, J. O. (1956). J. Am. Chem. Soc. 78, 3210-3216.]; Garden, Torres et al., 2001[Garden, S. J., Torres, J. C., de Souza Melo, S. C., Lima, A. S., Pinto, A. C. & Lima, E. D. S. (2001). Tetrahedron Lett. 42, 2089-2092.]) gave, in addition to 2-iodo-5-nitro­aniline, (I[link]), and 2,4-di­iodo-3-nitro­aniline, (II[link]), a third compound in very low yield. This is presumably an intermediate in the formation of (II[link]), viz. either 2-iodo-3-nitro­aniline, (III[link]), or more plausibly 4-iodo-3-nitro­aniline, (IV[link]), but it had not been isolated when the structures of (I[link]) and (II[link]) were reported (Garden et al., 2002[Garden, S. J., Fontes, S. P., Wardell, J. L., Skakle, J. M. S., Low, J. N. & Glidewell, C. (2002). Acta Cryst. B58, 701-709.]). This intermediate has now been isolated and crystallized and we report here the molecular and supramolecular structures of this product, 4-iodo-3-nitro­aniline, (IV[link]). The supramolecular structure proves to be different from any of those adopted by its isomers (I[link]), (V[link]) and (VI[link]).

The O atoms of the nitro group in (IV[link]) are disordered over two sets of sites of equal occupancy (Fig. 1[link]). The nitro groups defined by atoms O3A and O3B on the one hand and O3C and O3D on the other are both twisted out of the plane of the aryl ring by ca 13° and ca 35°, respectively, such that the dihedral angle between the two nitro-group planes is ca 48°. However, despite their equal occupancies, the occupation of the two alternative sets of sites cannot be entirely random. In order to avoid a very short contact of 2.518 (12) Å between atoms O3C and O3D in the mol­ecules at (x, y, z) and (x, 1 + y, z), respectively, adjacent molecular sites related by translation along [010] cannot both accommodate the nitro-group orientation involving atoms O3C and O3D. Since both orientations must occur with equal frequency in a given [010] stack, there must be a strict alternation along [010] of the occupation of the two alternative sets of sites. Hence, there must be perfect correlation of the occupancies along any one [010] stack, although without any necessary correlation of the occupancies in any given [010] stack with those in the neighbouring stacks. Accordingly, the structure is correctly described in terms of the present unit cell with Z = 4, rather than of a larger unit cell with Z = 8.

[Scheme 1]

The amino N atom is pyramidal, as judged by the locations of the corresponding H atoms found from difference maps. Consistent with this, the C1—N1 distance of 1.388 (5) Å is typical of Caryl—NH2 distances involving pyramidal nitrogen (mean value 1.394 Å and lower quartile value 1.385 Å; Allen et al., 1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-19.]), rather than of those involving planar N (mean value 1.355 Å and upper quartile value 1.372 Å). The remaining bond distances show no unusual values.

The supramolecular structure of compound (IV[link]) is determined by a combination of an asymmetric three-centre N—H⋯(O)2 hydrogen bond and a two-centre N—H⋯N hydrogen bond (Table 1[link]). However, X—H⋯π(arene) hydrogen bonds (X is C or N), intermolecular iodo–nitro interactions and aromatic ππ stacking interactions are all absent.

The amino atom N1 in the mol­ecule at (x, y, z) acts as hydrogen-bond donor, via atom H1A, to O atoms in the mol­ecule at ([{1 \over 2}] + x, [{3 \over 2}] − y, [{1 \over 2}] + z), either to both O3A and O3B in one orientation of the nitro group, or to both O3C and O3D in the other orientation. No matter which pair of O-atom sites is occupied, the mol­ecules at (x, y, z) and ([{1 \over 2}] + x, [{3 \over 2}] − y, [{1 \over 2}] + z) are linked by a nearly planar three-centre interaction. Propagation of this interaction then produces a C(7)[R12(4)] (Bernstein et al., 1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.]) chain of rings running parallel to the [101] direction and generated by the n-glide plane at y = [{3 \over 4}] (Fig. 2[link]).

The [101] chains are linked by the nearly linear two-centre N—H⋯N hydrogen bond, in which amino atom N1 in the mol­ecule at (x, y, z) acts as donor, via atom H1B, to atom N1 in the mol­ecule at ([{1 \over 2}] − x, [{1 \over 2}] + y, [{3 \over 2}] − z), thereby forming a C(2) chain running parallel to the [010] direction and generated by the 21 screw axis along ([{1 \over 4}], y, [{3 \over 4}]) (Fig. 3[link]). The combination of the [101] and [010] chains generates a (10[\overline 1]) sheet (Fig. 4[link]) in the form of a (4,4)-net (Batten & Robson, 1998[Batten, S. R. & Robson, R. (1998). Angew. Chem. Int. Ed. 37, 1460-1494.]).

It is of interest to compare very briefly the rather simple supramolecular structure of compound (IV[link]) with those of the isomers (I[link]), (V[link]) and (VI[link]). In (I[link]), hydrogen-bonded dimers are linked into sheets by two-centre iodo–nitro interactions, and these sheets are linked into a three-dimensional framework by aromatic ππ stacking interactions (Garden et al., 2002[Garden, S. J., Fontes, S. P., Wardell, J. L., Skakle, J. M. S., Low, J. N. & Glidewell, C. (2002). Acta Cryst. B58, 701-709.]). In compound (V[link]), where Z′ = 2, each of the two independent mol­ecules forms sheets via a combination of N—H⋯O hydrogen bonds and two-centre iodo–nitro interactions, but there are no direction-specific interactions between the two types of sheet (Garden et al., 2002[Garden, S. J., Fontes, S. P., Wardell, J. L., Skakle, J. M. S., Low, J. N. & Glidewell, C. (2002). Acta Cryst. B58, 701-709.]). Compound (VI[link]) forms two polymorphs and in each a combination of hydrogen bonds and iodo–nitro interactions generates sheets, which are linked by aromatic ππ stacking interactions into bilayers in the triclinic polymorph and into a three-dimensional framework in the orthorhombic polymorph (McWilliam et al., 2001[McWilliam, S. A., Skakle, J. M. S., Low, J. N., Wardell, J. L., Garden, S. J., Pinto, A. C., Torres, J. C. & Glidewell, C. (2001). Acta Cryst. C57, 942-945.]). It is striking that iodo–nitro interactions are present in the structures of each of compounds (I[link]), (V[link]) and (VI[link]), but that these interactions are absent from the structure of (IV[link]).

[Figure 1]
Figure 1
The mol­ecule of (IV[link]), showing the atom-labelling scheme and the disordered O atoms. Displacement ellipsoids are drawn at the 30% probability level.
[Figure 2]
Figure 2
Part of the crystal structure of (IV[link]), showing the formation of the hydrogen-bonded chain of rings along [101]. For the sake of clarity, H atoms bonded to C atoms have been omitted, and only one pair of O atoms, O3A and O3B, is shown. Atoms marked with an asterisk (*), hash (#) or dollar sign ($) are at the symmetry positions ([{1 \over 2}] + x, [{3 \over 2}] − y, [{1 \over 2}] + z), (1 + x, y, 1 + z) and (x − [{1 \over 2}], [{3 \over 2}] − y, z − [{1 \over 2}]), respectively.
[Figure 3]
Figure 3
Part of the crystal structure of (IV[link]), showing the formation of the hydrogen-bonded chain along [010]. For the sake of clarity, H atoms bonded to C atoms have been omitted, and only one orientation of the disordered nitro group is shown. Atoms marked with an asterisk (*), hash (#) or dollar sign ($) are at the symmetry positions ([{1 \over 2}] − x, [{1 \over 2}] + y, [{3 \over 2}] − z), (x, 1 + y, z) and ([{1 \over 2}] − x, y − [{1 \over 2}], [{3 \over 2}] − z), respectively.
[Figure 4]
Figure 4
A stereoview of part of the crystal structure of (IV[link]), showing the formation of the (10[\overline 1]) sheet resulting from the combination of [101] and [010] chains. For the sake of clarity, H atoms bonded to C atoms have been omitted, and only one orientation of the disordered nitro group is shown.

Experimental

For the preparation of (IV[link]), a solution of K[ICl2] (2.5 ml, 2 M) in water was added to a solution of 3-nitro­aniline (10 mmol) in MeOH (18 ml). The reaction mixture was left at room temperature for a few hours, then heated to boiling and diluted with water (10 ml). The precipitate which formed on cooling was collected, washed with cold 50% aqueous methanol, and recrystallized from 50% aqueous methanol to give a cocrystallized mixture of 2-iodo-5-nitro­aniline, (I[link]), and 4-iodo-3-nitro­aniline, (IV[link]). These compounds were separated by column chromatography on silica gel using hexane–CH2Cl2 (1:1 v/v) as eluant. 4-Iodo-3-nitro­aniline (0.60 g, 45% yield based on K[ICl2]; m.p. 414–415 K) was recrystallized from aqueous methanol. 1H NMR (CDCl3/DMSO-d6, δ): 4.90 (2H, br, s, NH2), 6.62 (1H, H6, dd, J = 2.7 and 8.6 Hz), 7.20 (1H, H2, d, J = 2.7 Hz), 7.62 (1H, H5, d, J = 8.7 Hz); 13C NMR (CDCl3/DMSO-d6, δ): 67.6 (C—I), 110.7 (CH), 119.6 (CH), 141.1 (CH), 148.5 (C—NH2), 153.1 (C—NO2).

Crystal data
  • C6H5IN2O2

  • Mr = 264.02

  • Monoclinic, P21/n

  • a = 12.5174 (7) Å

  • b = 4.2601 (3) Å

  • c = 16.0042 (9) Å

  • β = 111.580 (1)°

  • V = 793.61 (8) Å3

  • Z = 4

  • Dx = 2.210 Mg m−3

  • Mo Kα radiation

  • Cell parameters from 2848 reflections

  • θ = 2.6–32.5°

  • μ = 3.99 mm−1

  • T = 291 (2) K

  • Plate, colourless

  • 0.50 × 0.05 × 0.05 mm

Data collection
  • Bruker SMART 1000 CCD area-detector diffractometer

  • φ/ω scans

  • Absorption correction: multi-scan (SADABS; Bruker, 2000[Bruker (2000). SADABS (Version 2.03) and SAINT (Version 6.02a). Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.456, Tmax = 0.819

  • 8259 measured reflections

  • 2848 independent reflections

  • 1971 reflections with I > 2σ(I)

  • Rint = 0.028

  • θmax = 32.5°

  • h = −17 → 18

  • k = −4 → 6

  • l = −22 → 24

Refinement
  • Refinement on F2

  • R[F2 > 2σ(F2)] = 0.039

  • wR(F2) = 0.107

  • S = 1.00

  • 2848 reflections

  • 100 parameters

  • H-atom parameters constrained

  • w = 1/[σ2(Fo2) + (0.0553P)2 + 0.2861P] where P = (Fo2 + 2Fc2)/3

  • (Δ/σ)max < 0.001

  • Δρmax = 1.10 e Å−3

  • Δρmin = −0.85 e Å−3

Table 1
Hydrogen-bonding geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1A⋯O3Ai 0.88 2.50 3.265 (8) 146
N1—H1A⋯O3Bi 0.88 2.35 3.148 (8) 150
N1—H1A⋯O3Di 0.88 2.58 3.298 (8) 140
N1—H1A⋯O3Ci 0.88 2.46 3.295 (8) 158
N1—H1B⋯N1ii 0.88 2.25 3.105 (6) 164
Symmetry codes: (i) [{\script{1\over 2}}+x,{\script{3\over 2}}-y,{\script{1\over 2}}+z]; (ii) [{\script{1\over 2}}-x,{\script{1\over 2}}+y,{\script{3\over 2}}-z].

The space group P21/n was uniquely assigned from the systematic absences. All H atoms were located from difference maps. H atoms bonded to C atoms were treated as riding atoms along the bisectors of the external angles of the aryl ring, with C—H distances of 0.93 Å. The sites of the H atoms bonded to atom N1 showed clearly the pyramidal geometry of the amino group; these H atoms were allowed to ride at the sites found from the difference maps, with the N—H distances constrained to 0.88 Å. For all H atoms, Uiso(H) = 1.2Ueq(C,N). It was found necessary to assign equal anisotropic displacement parameters to the partial O-atom sites in order to achieve satisfactory refinements of the O atoms. When the site-occupancy factors of the O atoms in the alternative orientations of the nitro group were then refined, they gave values of 0.51 (3) and 0.49 (3); these occupancies were all thereafter fixed at 0.50.

Data collection: SMART (Bruker, 1998[Bruker (1998). SMART. Version 5.0. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2000[Bruker (2000). SADABS (Version 2.03) and SAINT (Version 6.02a). Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: OSCAIL (McArdle, 2003[McArdle, P. (2003). OSCAIL for Windows. Version 10. Crystallography Centre, Chemistry Department, NUI Galway, Ireland.]) and SHELXS97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); program(s) used to refine structure: OSCAIL and SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); molecular graphics: PLATON (Spek, 2003[Spek, A. L. (2003). J. Appl. Cryst. 36, 7-13.]); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999[Ferguson, G. (1999). PRPKAPPA. University of Guelph, Canada.]).

Supporting information


Comment top

We have recently reported the molecular and supramolecular structures of a number of iodo-nitroanilines, no two of which exhibit in their supramolecular structures the same pattern of N—H···O hydrogen bonds, iodo···nitro interactions or aromatic ππ stacking interactions (Garden, Glidewell et al., 2001; McWilliam et al., 2001, Garden et al., 2002).

Iodination of 3-nitroaniline, using a solution of K[ICl2] in methanol as the iodinating agent (Larsen et al., 1956; Garden, Torres et al., 2001) gave, in addition to 2-iodo-5-nitroaniline, (I), and 2,4-diiodo-3-nitroaniline, (II), a third compound, in very low yield. This is presumably an intermediate in the formation of (II), either 2-iodo-3-nitroaniline, (III), or, more plausibly, 4-iodo-3-nitroaniline, (IV), but it had not been isolated when the structures of (I) and (II) were reported (Garden et al., 2002). This compound has now been isolated and crystallized, and we report here the molecular and supramolecular structures of this product, 4-iodo-3-nitroaniline, (IV). The supramolecular structure proves to be different from any of those adopted by its isomers (I), (V) and (VI). \sch

The O atoms of the nitro group in (IV) are disordered over two sets of sites of equal occupancy (Fig. 1). The nitro groups defined by atoms O3A and O3B, on the one hand, and O3C and O3D on the other, are both twisted out of the plane of the aryl ring by ca 13 and ca 35°, respectively, such that the dihedral angle between the two nitro-group planes is ca 48°. However, despite their equal occupancies, the occupation of the two alternative sets of sites cannot be entirely random. In order to avoid a very short contact of 2.518 (12) Å between atoms O3C and O3D in the molecules at (x, y, z) and (x, 1 + y, z), respectively, adjacent molecular sites related by translation along [010] cannot both accommodate the nitro-group orientation involving atoms O3C and O3D. Since both orientations must occur with equal frequency in a given [010] stack, there must be a strict alternation along [010] of the occupation of the two alternative sets of sites. Hence, there must be perfect correlation of the occupancies along any one [010] stack, although without any necessary correlation of the occupancies in any given [010] stack with those in the neighbouring stacks. Accordingly, the structure is correctly described in terms of the present unit cell with Z = 4, rather than of a larger unit cell with Z = 8.

The amino N atom is pyramidal, as judged by the locations of the corresponding H atoms found from difference maps. Consistent with this, the C1—N1 distance of 1.388 (5) Å is typical of C(aryl)-NH2 distances involving pyramidal N (mean value 1.394 Å, lower quartile value 1.385 Å; Allen et al., 1987), rather than of those involving planar N (mean value 1.355 Å, upper quartile value 1.372 Å). The remaining bond distances show no unusual values.

The supramolecular structure of compound (IV) is determined by a combination of an asymmetric three-centre N—H···(O)2 hydrogen bond and a two-centre N—H···N hydrogen bond (Table 1). However, X—H···π(arene) hydrogen bonds (X is C or N), intermolecular iodo···nitro interactions and aromatic ππ stacking interactions are all absent.

The amino atom N1 in the molecule at (x, y, z) acts as hydrogen-bond donor, via atom H1A, to O atoms in the molecule at (1/2 + x, 3/2 − y, 1/2 + z), either to both O3A and O3B in one orientation of the nitro group, or to both O3C and O3D in the other orientation. No matter which pair of O sites is occupied, the molecules at (x, y, z) and (1/2 + x, 3/2 − y, 1/2 + z) are linked by a nearly-planar three-centre interaction. Propagation of this interaction then produces a C(7)[R12(4)] (Bernstein et al., 1995) chain of rings running parallel to the [101] direction and generated by the n-glide plane at y = 3/4 (Fig. 2).

The [101] chains are linked by the nearly-linear two-centre N—H···N hydrogen bond, in which amino atom N1 in the molecule at (x, y, z) acts as donor, via atom H1B, to atom N1 in the molecule at (1/2 − x, 1/2 + y, 3/2 − z), thereby forming a C(2) chain running parallel to the [010] direction and generated by the 21 screw axis along (1/4, y, 3/4) (Fig. 3). The combination of the [101] and [010] chains generates a (101) sheet (Fig. 4) in the form of a (4,4) net (Batten & Robson, 1998).

It is of interest to compare very briefly the rather simple supramolecular structure of compound (IV) with those of the isomers (I), (V) and (VI). In (I), hydrogen-bonded dimers are linked into sheets by a two-centre iodo···nitro interactions, and these sheets are linked into a three-dimensional framework by aromatic ππ stacking interactions (Garden et al., 2002). In compound (V), where Z' = 2, each of the two independent molecules forms sheets via a combination of N—H···O hydrogen bonds and two-centre iodo···nitro interactions, but there are no direction-specific interactions between the two types of sheet (Garden et al., 2002). Compound (VI) forms two polymorphs, and in each a combination of hydrogen bonds and iodo···nitro interactions generates sheets, which are linked by aromatic ππ stacking interactions into bilayers in the triclinic polymorph and into a three-dimensional framework in the orthorhombic polymorph (McWilliam et al., 2001). It is striking that iodo···nitro interactions are present in the structures of each of compounds (I), (V) and (VI), but that these interactions are absent from the structure of (IV).

Experimental top

For the preparation of (IV), a solution of K[ICl2] (2.5 ml, 2 M) in water was added to a solution of 3-nitroaniline (10 mmol) in MeOH (18 ml). The reaction mixture was left at room temperature for a few hours, then heated to boiling and diluted with water (10 ml). The precipitate which formed on cooling was collected, washed with cold 50% aqueous methanol, and recrystallized from 50% aqueous methanol to give a co-crystallized mixture of 2-iodo-5-nitroaniline, (I), and 4-iodo-3-nitroaniline, (IV). These compounds were separated by column chromatography on silica gel using hexane/CH2Cl2 (Ratio?) as eluent. 4-Iodo-3-nitroaniline (0.60 g, 45% yield based upon K[ICl2], m.p. 414–415 K) was recrystallized from aqueous methanol. 1H NMR (CDCl3/DMSO-d6, δ, p.p.m.): 4.90 (2H, br, s, NH2), 6.62 (1H, H-6, dd, J = 2.7 and8.6 Hz), 7.20 (1H, H-2, d, J = 2.7 Hz), 7.62 (1H, H-5, d, J = 8.7 Hz); 13C NMR (CDCl3/DMSO-d6, δ, p.p.m.): 67.6 (C—I), 110.7 (CH), 119.6 (CH), 141.1 (CH), 148.5 (C—NH2), 153.1 (C—NO2).

Refinement top

The space group P21/n was uniquely assigned from the systematic absences. All H atoms were located from difference maps. H atoms bonded to C atoms were treated as riding atoms along the bisectors of the external angles of the aryl ring, with C—H distances of 0.93 Å. The sites of the H atoms bonded to atom N1 showed clearly the pyramidal geometry of the amino group: these H atoms were allowed to ride at the sites found from the difference maps, with the N—H distances constrained to 0.88 Å. For all H atoms, Uiso(H) = 1.2Ueq(C,N). It was found necessary to assign equal anisotropic displacement parameters to the partial O sites in order to achieve satisfactory refinements of the O atoms. When the site-occupancy factors of the O atoms in the alternative orientations of the nitro group were then refined, they gave values of 0.51 (3) and 0.49 (3); these occupancies were all thereafter fixed at 0.50.

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
[Figure 1] Fig. 1. The molecule of (IV), showing the atom-labelling scheme and the disordered O atoms. Displacement ellipsoids are drawn at the 30% probability level.
[Figure 2] Fig. 2. Part of the crystal structure of (IV), showing formation of the hydrogen-bonded chain of rings along [101]. For the sake of clarity, H atoms bonded to C atoms have been omitted, and only one pair of O atoms, O3A and O3B, is shown. The atoms marked with an asterisk (*), hash (#) or dollar sign () are at the symmetry positions (1/2 + x, 3/2 − y, 1/2 + z), (1 + x, y, 1 + z) and (x − 1/2, 3/2 − y, z − 1/2), respectively.
[Figure 3] Fig. 3. Part of the crystal structure of (IV), showing formation of the hydrogen-bonded chain along [010]. For the sake of clarity, H atoms bonded to C atoms have been omitted, and only one orientation of the disordered nitro group is shown. The atoms marked with an asterisk (*), hash (#) or dollar sign () are at the symmetry positions (1/2 − x, 1/2 + y, 3/2 − z), (x, 1 + y, z) and (1/2 − x, y − 1/2, 3/2 − z), respectively.
[Figure 4] Fig. 4. A stereoview of part of the crystal structure of (IV), showing formation of the (101) sheet resulting from the combination of [101] and [010] chains. For the sake of clarity, H atoms bonded to C atoms have been omitted, and only one orientation of the disordered nitro group is shown.
4-iodo-3-nitroaniline top
Crystal data top
C6H5IN2O2F(000) = 496
Mr = 264.02Dx = 2.210 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 2848 reflections
a = 12.5174 (7) Åθ = 2.6–32.5°
b = 4.2601 (3) ŵ = 3.99 mm1
c = 16.0042 (9) ÅT = 291 K
β = 111.580 (1)°Plate, colourless
V = 793.61 (8) Å30.50 × 0.05 × 0.05 mm
Z = 4
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer
2848 independent reflections
Radiation source: fine-focus sealed X-ray tube1971 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.028
ϕ/ω scansθmax = 32.5°, θmin = 2.6°
Absorption correction: multi-scan
(SADABS; Bruker, 2000)
h = 1718
Tmin = 0.456, Tmax = 0.819k = 46
8259 measured reflectionsl = 2224
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)] = 0.039Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.107H-atom parameters constrained
S = 1.00 w = 1/[σ2(Fo2) + (0.0553P)2 + 0.2861P]
where P = (Fo2 + 2Fc2)/3
2848 reflections(Δ/σ)max < 0.001
100 parametersΔρmax = 1.10 e Å3
0 restraintsΔρmin = 0.85 e Å3
Crystal data top
C6H5IN2O2V = 793.61 (8) Å3
Mr = 264.02Z = 4
Monoclinic, P21/nMo Kα radiation
a = 12.5174 (7) ŵ = 3.99 mm1
b = 4.2601 (3) ÅT = 291 K
c = 16.0042 (9) Å0.50 × 0.05 × 0.05 mm
β = 111.580 (1)°
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer
2848 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2000)
1971 reflections with I > 2σ(I)
Tmin = 0.456, Tmax = 0.819Rint = 0.028
8259 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0390 restraints
wR(F2) = 0.107H-atom parameters constrained
S = 1.00Δρmax = 1.10 e Å3
2848 reflectionsΔρmin = 0.85 e Å3
100 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
I40.28665 (2)0.16650 (6)0.356645 (15)0.06100 (12)
O3A0.0122 (6)0.682 (2)0.4378 (5)0.0840 (15)0.50
O3B0.0796 (6)0.538 (2)0.3416 (5)0.0840 (15)0.50
O3C0.0469 (6)0.833 (2)0.4266 (6)0.0840 (15)0.50
O3D0.0510 (6)0.376 (2)0.3657 (5)0.0840 (15)0.50
N10.3297 (3)0.7166 (11)0.7327 (2)0.0707 (10)
N30.0928 (3)0.5822 (9)0.4213 (2)0.0567 (8)
C10.3197 (3)0.6074 (10)0.6485 (2)0.0521 (8)
C20.2173 (3)0.6486 (9)0.5757 (2)0.0460 (7)
C30.2052 (2)0.5254 (9)0.49309 (19)0.0436 (6)
C40.2922 (3)0.3615 (8)0.4779 (2)0.0455 (7)
C50.3944 (3)0.3240 (10)0.5519 (3)0.0563 (9)
C60.4073 (3)0.4401 (12)0.6344 (2)0.0598 (10)
H1A0.39860.72210.77520.085*
H1B0.27450.84620.73160.085*
H20.15700.75890.58280.055*
H50.45520.21720.54460.068*
H60.47610.40680.68240.072*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
I40.0921 (2)0.04963 (16)0.04865 (15)0.00516 (12)0.03457 (13)0.00129 (10)
O3A0.056 (2)0.112 (5)0.065 (2)0.007 (2)0.0015 (17)0.016 (3)
O3B0.056 (2)0.112 (5)0.065 (2)0.007 (2)0.0015 (17)0.016 (3)
O3C0.056 (2)0.112 (5)0.065 (2)0.007 (2)0.0015 (17)0.016 (3)
O3D0.056 (2)0.112 (5)0.065 (2)0.007 (2)0.0015 (17)0.016 (3)
N10.0607 (18)0.103 (3)0.0408 (15)0.0103 (19)0.0096 (13)0.0162 (18)
N30.0464 (15)0.073 (2)0.0440 (15)0.0001 (15)0.0084 (12)0.0019 (14)
C10.0466 (16)0.066 (2)0.0384 (14)0.0117 (15)0.0097 (12)0.0046 (14)
C20.0407 (14)0.0572 (19)0.0378 (13)0.0006 (14)0.0117 (11)0.0030 (14)
C30.0429 (14)0.0466 (17)0.0371 (13)0.0054 (13)0.0095 (11)0.0022 (13)
C40.0556 (17)0.0443 (16)0.0369 (13)0.0003 (14)0.0175 (12)0.0044 (13)
C50.0477 (16)0.069 (2)0.0506 (18)0.0112 (17)0.0157 (14)0.0104 (18)
C60.0455 (16)0.079 (3)0.0461 (17)0.0011 (18)0.0066 (13)0.0106 (18)
Geometric parameters (Å, º) top
C1—N11.388 (5)N3—O3A1.211 (9)
C1—C21.390 (4)N3—O3D1.223 (8)
C1—C61.393 (6)N3—O3C1.232 (9)
N1—H1A0.88N3—O3B1.239 (8)
N1—H1B0.88C4—C51.396 (5)
C2—C31.379 (5)C4—I42.089 (3)
C2—H20.93C5—C61.363 (6)
C3—C41.388 (5)C5—H50.93
C3—N31.472 (4)C6—H60.93
N1—C1—C2119.8 (4)O3C—N3—O3B108.3 (7)
N1—C1—C6122.2 (3)O3A—N3—C3121.4 (4)
C2—C1—C6117.9 (3)O3D—N3—C3118.7 (5)
C1—N1—H1A118.2O3C—N3—C3115.2 (4)
C1—N1—H1B113.7O3B—N3—C3120.4 (4)
H1A—N1—H1B122.5C3—C4—C5116.3 (3)
C3—C2—C1119.8 (3)C3—C4—I4127.1 (2)
C3—C2—H2120.1C5—C4—I4116.7 (3)
C1—C2—H2120.1C6—C5—C4121.7 (4)
C2—C3—C4122.9 (3)C6—C5—H5119.2
C2—C3—N3115.0 (3)C4—C5—H5119.2
C4—C3—N3122.1 (3)C5—C6—C1121.4 (3)
O3A—N3—O3D104.1 (6)C5—C6—H6119.3
O3D—N3—O3C126.0 (5)C1—C6—H6119.3
O3A—N3—O3B118.2 (5)
N1—C1—C2—C3176.5 (4)C4—C3—N3—O3B13.8 (8)
C6—C1—C2—C30.1 (5)C2—C3—C4—C50.5 (5)
C1—C2—C3—C40.7 (5)N3—C3—C4—C5179.9 (3)
C1—C2—C3—N3179.7 (3)C2—C3—C4—I4179.4 (3)
C2—C3—N3—O3A11.7 (8)N3—C3—C4—I40.3 (5)
C4—C3—N3—O3A168.6 (7)C3—C4—C5—C60.5 (6)
C2—C3—N3—O3D143.1 (6)I4—C4—C5—C6179.6 (3)
C4—C3—N3—O3D37.3 (7)C4—C5—C6—C11.3 (7)
C2—C3—N3—O3C33.2 (7)N1—C1—C6—C5177.4 (4)
C4—C3—N3—O3C146.5 (6)C2—C1—C6—C51.1 (6)
C2—C3—N3—O3B165.9 (6)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···O3Ai0.882.503.265 (8)146
N1—H1A···O3Bi0.882.353.148 (8)150
N1—H1A···O3Di0.882.583.298 (8)140
N1—H1A···O3Ci0.882.463.295 (8)158
N1—H1B···N1ii0.882.253.105 (6)164
Symmetry codes: (i) x+1/2, y+3/2, z+1/2; (ii) x+1/2, y+1/2, z+3/2.

Experimental details

Crystal data
Chemical formulaC6H5IN2O2
Mr264.02
Crystal system, space groupMonoclinic, P21/n
Temperature (K)291
a, b, c (Å)12.5174 (7), 4.2601 (3), 16.0042 (9)
β (°) 111.580 (1)
V3)793.61 (8)
Z4
Radiation typeMo Kα
µ (mm1)3.99
Crystal size (mm)0.50 × 0.05 × 0.05
Data collection
DiffractometerBruker SMART 1000 CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2000)
Tmin, Tmax0.456, 0.819
No. of measured, independent and
observed [I > 2σ(I)] reflections
8259, 2848, 1971
Rint0.028
(sin θ/λ)max1)0.756
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.039, 0.107, 1.00
No. of reflections2848
No. of parameters100
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.10, 0.85

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).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···O3Ai0.882.503.265 (8)146
N1—H1A···O3Bi0.882.353.148 (8)150
N1—H1A···O3Di0.882.583.298 (8)140
N1—H1A···O3Ci0.882.463.295 (8)158
N1—H1B···N1ii0.882.253.105 (6)164
Symmetry codes: (i) x+1/2, y+3/2, z+1/2; (ii) x+1/2, y+1/2, z+3/2.
 

Acknowledgements

X-ray data were collected at the University of Aberdeen; the authors thank the University of Aberdeen for funding the purchase of the diffractometer. JNL thanks NCR Self-Service, Dundee, for grants which have provided computing facilities for this work. SLG and JLW thank CNPq and FAPERJ for financial support.

References

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