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Acta Crystallogr Sect E Struct Rep Online. 2008 December 1; 64(Pt 12): m1598.
Published online 2008 November 22. doi:  10.1107/S1600536808038415
PMCID: PMC2960147

Bis(2-methyl-4-nitro­anilinium) tetra­chloridomercurate(II)

Abstract

The title compound, (C7H9N2O2)2[HgCl4], self-assembles into cationic organic bilayers containing the 2-methyl-4-nitro­anilinium cations, sandwiched between anionic inorganic layers built up by the distorted tetra­hedral [HgCl4]2− groups. The organic sheets are inter­linked through weak C—H(...)O hydrogen bonds, while they inter­act with the anionic part via strong charge-assisted N+—H(...)Cl—Hg hydrogen bonds. The [HgCl4]2− anions are bis­ected by a mirror plane passing through the metal and two of the chloride ions.

Related literature

The structures of bis­(2-methyl-4-nitro­anilinium) tetra­chloro­cadmate (Azumi et al., 1996 [triangle]) as well as those of the bromide and iodide salts of 2-methyl-4-nitro­anilinium (Lemmerer & Billing, 2006 [triangle]) have already been reported. For related literature on C—H(...)Onitro inter­actions, see: Sharma & Desiraju (1994 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-m1598-scheme1.jpg

Experimental

Crystal data

  • (C7H9N2O2)2[HgCl4]
  • M r = 648.71
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-64-m1598-efi4.jpg
  • a = 8.2527 (11) Å
  • b = 30.059 (4) Å
  • c = 8.3038 (10) Å
  • V = 2059.9 (5) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 8.02 mm−1
  • T = 173 (2) K
  • 0.42 × 0.25 × 0.16 mm

Data collection

  • Bruker SMART CCD area-detector diffractometer
  • Absorption correction: integration (XPREP; Bruker, 1999 [triangle]) T min = 0.609, T max = 0.757
  • 10307 measured reflections
  • 3174 independent reflections
  • 2197 reflections with I > 2σ(I)
  • R int = 0.091

Refinement

  • R[F 2 > 2σ(F 2)] = 0.053
  • wR(F 2) = 0.152
  • S = 1.09
  • 3174 reflections
  • 129 parameters
  • H-atom parameters constrained
  • Δρmax = 1.05 e Å−3
  • Δρmin = −2.89 e Å−3

Data collection: SMART-NT (Bruker, 1998 [triangle]); cell refinement: SAINT-Plus (Bruker, 1999 [triangle]); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: DIAMOND (Brandenburg, 2006 [triangle]) and Mercury (Bruno et al., 2002 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]) and PLATON (Spek, 2003 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808038415/bg2223sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808038415/bg2223Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

MR acknowledges funding from the NRF (GUN: 2054350), the University of Pretoria and the University of KwaZulu-Natal. DGB thanks the University of the Witwatersrand for infrastructure.

supplementary crystallographic information

Comment

As part of a study focused on the fundamental understanding of the non-covalent interactions occurring in organic-inorganic hybrids, the structure of bis(2-methyl-4-nitroanilinium) tetrachloromercurate, 2(C7H9N2O2)+.(HgCl4)2-, (I), was determined. It was found that the title compound is isostructural to the previously reported hybrid, bis(2-methyl-4-nitroanilinium) tetrachlorocadmate (Azumi et al., 1996). The structures of the bromide and iodide salts of the 2-methyl-4-nitroanilinium cation have already been reported (Lemmerer & Billing, 2006).

The molecular geometry and atomic numbering scheme of (I) are illustrated in Fig. 1. The asymmetric unit contains one 2-methyl-4-nitroanilinium cation and a HgCl42- anion, halved by a mirror plane (x, 1/2-y, z) passing through the metal and two of the chlorine ions. The structure consists of alternating, non-interdigitated organic bilayers containing the 2-methyl-4-nitroanilium cations, and inorganic layers containing the isolated (HgCl4)2- anions (Fig. 2.).

In the organic bilayers the nitro groups pack in the centre of the layer, in a tail-to-tail arrangement, and the aromatic ring plane (C1->C6) forms an angle of 86.3° to the inorganic layer plane. It has been reported by Sharma and Desiraju (1994) that weak C—H···O interactions, with the nitro group as a hydrogen bond acceptor occurs in many unsaturated compounds, despite the fact that the nitro group is not very basic, and it is precisely this type of interaction the one which links both organic layers in (I): atom C3 on the aromatic ring at symmetry position (1/2 - x, 1/2 + y, z - 1/2) acts as proton donor while the O1 of nitro group at symmetry position (x, 1/2 - y, z) acts as acceptor, with an H···O distance of 2.52 Å.

The organic and inorganic layers are linked through charge assisted N+—H···Cl—Hg hydrogen bonds, with the hydrogen bonding interactions listed in Table 1. N1 is the only hydrogen bond donor with all three hydrogen atoms involved in hydrogen bonding. Atom H6 is shared by two chlorine atoms (Cl2 at symmetry position: (x, y, z) and Cl3 at symmetry position: (x - 1/2, 1/2 - y, 1/2 - z)) and thus forms a bifurcated interaction. Two approximately linear hydrogen bonds are formed through atoms H4 and H5 with Cl1 at symmetry positions (x - 1, y, z) and (x - 1/2, y, 1/2 - z), respectively. All four chloro ligands on the HgCl42- anion act as hydrogen bond acceptors.

Experimental

Compound (I) was prepared by the addition of 0.097 g (0.357 mmol) of HgCl2 (Aldrich) and 0.102 g (0.333 mmol) of 2-methyl-4-nitroaniline (Aldrich) to 6 ml of 33% HCl. Complete dissolution was obtained after refluxing at 90°C for 12 h in an oil bath. Slow cooling in oil bath over 48 h produced the crystals. A colourless crystal of 0.42 x 1/4x 0.16 mm was used for X-ray data collection.

Refinement

H atoms were placed geometrically and refined in idealized positions in the riding-model approximation, with C—H 0.95 (ArH) and 0.98 Å (CH3) and N—H = 0.91 Å; Uiso(H) = 1.5Ueq(N), 1.5Ueq(C) for methyl H atoms and 1.2Ueq(C) for other H atoms. The highest residual peaks in the final ΔF syntheses lie at 0.90 Å from Cl3.

Figures

Fig. 1.
Atom labelling scheme of (I) with thermal ellipsoids drawn at the 50% probability level. The Cl atom marked with a prime (') is at symmetry position (1/2 + x, 1/2 - y, 1/2 - z).
Fig. 2.
Packing arrangement viewed down the c-axis.

Crystal data

(C7H9N2O2)2[HgCl4]Dx = 2.092 Mg m3
Mr = 648.71Melting point: 441 K
Orthorhombic, PnmaMo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2ac 2nCell parameters from 937 reflections
a = 8.2527 (11) Åθ = 3.2–28.3º
b = 30.059 (4) ŵ = 8.02 mm1
c = 8.3038 (10) ÅT = 173 (2) K
V = 2059.9 (5) Å3Plate, colourless
Z = 40.42 × 0.25 × 0.16 mm
F000 = 1240

Data collection

Bruker SMART CCD area-detector diffractometer3174 independent reflections
Radiation source: fine-focus sealed tube2197 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.091
T = 173(2) Kθmax = 32.2º
ω scansθmin = 1.4º
Absorption correction: integration(XPREP; Bruker, 1999)h = −11→12
Tmin = 0.609, Tmax = 0.757k = −38→44
10307 measured reflectionsl = −8→11

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.053H-atom parameters constrained
wR(F2) = 0.152  w = 1/[σ2(Fo2) + (0.077P)2 + 1.1955P] where P = (Fo2 + 2Fc2)/3
S = 1.09(Δ/σ)max = 0.003
3174 reflectionsΔρmax = 1.05 e Å3
129 parametersΔρmin = −2.89 e Å3
Primary atom site location: structure-invariant direct methodsExtinction correction: none

Special details

Experimental. Numerical integration absorption corrections based on indexed crystal faces were applied using the XPREP routine (Bruker, 2004)
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

xyzUiso*/Ueq
Hg10.60393 (5)0.25000.46538 (6)0.02730 (16)
Cl30.4637 (3)0.25000.1888 (3)0.0232 (5)
Cl10.6690 (2)0.17293 (6)0.5175 (2)0.0198 (3)
C10.1288 (8)0.1395 (2)0.5286 (9)0.0167 (13)
C60.2495 (9)0.1443 (3)0.4129 (9)0.0210 (15)
H30.27940.17310.37600.025*
O10.4612 (9)0.0300 (2)0.2467 (9)0.0504 (19)
O20.3238 (8)−0.00979 (19)0.4124 (8)0.0394 (15)
N10.0546 (7)0.1794 (2)0.5922 (8)0.0194 (12)
H60.08910.20340.53470.029*
H50.08320.18280.69730.029*
H4−0.05510.17720.58450.029*
C20.0779 (7)0.0982 (2)0.5872 (8)0.0151 (13)
N20.3592 (7)0.0258 (2)0.3538 (8)0.0252 (14)
C40.2790 (8)0.0663 (3)0.4125 (8)0.0189 (14)
C30.1558 (8)0.0608 (2)0.5265 (8)0.0171 (13)
H10.12570.03190.56190.021*
C50.3261 (8)0.1068 (2)0.3516 (8)0.0199 (14)
H20.40750.10910.27110.024*
C7−0.0544 (9)0.0924 (2)0.7085 (9)0.0223 (16)
H9−0.06260.06100.73830.033*
H8−0.15750.10230.66210.033*
H7−0.02990.11020.80450.033*
Cl20.3444 (3)0.25000.6670 (3)0.0199 (5)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Hg10.0319 (2)0.0206 (2)0.0293 (3)0.0000.00001 (19)0.000
Cl30.0272 (13)0.0262 (13)0.0162 (11)0.000−0.0057 (10)0.000
Cl10.0186 (8)0.0166 (8)0.0243 (8)0.0002 (6)−0.0007 (7)0.0008 (7)
C10.018 (3)0.016 (3)0.017 (3)0.000 (3)−0.003 (3)−0.002 (3)
C60.022 (3)0.024 (4)0.017 (3)−0.006 (3)0.000 (3)−0.001 (3)
O10.057 (4)0.039 (4)0.055 (4)−0.007 (4)0.038 (4)−0.013 (3)
O20.047 (4)0.020 (3)0.051 (4)0.005 (3)0.012 (3)−0.007 (3)
N10.010 (2)0.018 (3)0.030 (3)−0.001 (2)−0.003 (2)0.000 (3)
C20.010 (3)0.023 (4)0.013 (3)0.000 (2)−0.003 (2)0.001 (3)
N20.020 (3)0.027 (4)0.030 (4)0.000 (3)0.004 (2)−0.007 (3)
C40.019 (3)0.025 (4)0.013 (3)−0.003 (3)0.001 (3)−0.004 (3)
C30.015 (3)0.019 (3)0.017 (3)−0.004 (3)−0.003 (3)−0.002 (3)
C50.018 (3)0.024 (4)0.018 (3)−0.004 (3)0.005 (3)−0.001 (3)
C70.021 (3)0.022 (4)0.024 (4)0.001 (3)0.010 (3)0.003 (3)
Cl20.0143 (10)0.0189 (11)0.0266 (13)0.0000.0004 (9)0.000

Geometric parameters (Å, °)

Hg1—Cl12.4170 (18)N1—H50.9100
Hg1—Cl1i2.4170 (18)N1—H40.9100
Hg1—Cl32.572 (2)C2—C31.390 (10)
Hg1—Cl22.718 (2)C2—C71.496 (10)
C1—C61.392 (10)N2—C41.469 (10)
C1—C21.396 (10)C4—C51.375 (10)
C1—N11.447 (9)C4—C31.399 (10)
C6—C51.388 (10)C3—H10.9500
C6—H30.9500C5—H20.9500
O1—N21.230 (9)C7—H90.9800
O2—N21.212 (9)C7—H80.9800
N1—H60.9100C7—H70.9800
Cl1—Hg1—Cl1i146.85 (9)C1—C2—C7123.9 (6)
Cl1—Hg1—Cl3105.06 (4)O2—N2—O1123.0 (7)
Cl1i—Hg1—Cl3105.06 (4)O2—N2—C4119.3 (6)
Cl1—Hg1—Cl293.71 (5)O1—N2—C4117.6 (7)
Cl1i—Hg1—Cl293.71 (5)C5—C4—C3124.0 (7)
Cl3—Hg1—Cl2101.28 (8)C5—C4—N2119.0 (6)
C6—C1—C2123.2 (7)C3—C4—N2117.0 (6)
C6—C1—N1117.9 (6)C2—C3—C4119.0 (7)
C2—C1—N1118.9 (6)C2—C3—H1120.5
C5—C6—C1119.7 (7)C4—C3—H1120.5
C5—C6—H3120.2C4—C5—C6117.1 (6)
C1—C6—H3120.2C4—C5—H2121.5
C1—N1—H6109.5C6—C5—H2121.5
C1—N1—H5109.5C2—C7—H9109.5
H6—N1—H5109.5C2—C7—H8109.5
C1—N1—H4109.5H9—C7—H8109.5
H6—N1—H4109.5C2—C7—H7109.5
H5—N1—H4109.5H9—C7—H7109.5
C3—C2—C1117.0 (6)H8—C7—H7109.5
C3—C2—C7119.1 (7)
C2—C1—C6—C5−0.6 (11)O1—N2—C4—C3175.8 (7)
N1—C1—C6—C5178.6 (6)C1—C2—C3—C40.2 (9)
C6—C1—C2—C31.0 (10)C7—C2—C3—C4179.7 (7)
N1—C1—C2—C3−178.1 (6)C5—C4—C3—C2−2.1 (11)
C6—C1—C2—C7−178.4 (7)N2—C4—C3—C2179.1 (6)
N1—C1—C2—C72.4 (10)C3—C4—C5—C62.5 (11)
O2—N2—C4—C5176.5 (7)N2—C4—C5—C6−178.7 (6)
O1—N2—C4—C5−3.1 (10)C1—C6—C5—C4−1.2 (10)
O2—N2—C4—C3−4.6 (10)

Symmetry codes: (i) x, −y+1/2, z.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N1—H6···Cl20.912.763.257 (6)116
N1—H4···Cl1ii0.912.353.248 (6)170
N1—H5···Cl1iii0.912.493.381 (7)167
N1—H6···Cl3iv0.912.543.241 (7)134
C3—H1···O1v0.952.523.424 (10)160

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BG2223).

References

  • Azumi, R., Honda, K., Goto, M., Akimoto, J., Oosawa, Y., Tachibana, H., Tanaka, M. & Matsumoto, M. (1996). Acta Cryst. C52, 588–591.
  • Brandenburg, K. (2006). DIAMOND Crystal Impact GbR, Bonn, Germany.
  • Bruker (1998). SMART-NT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Bruker (1999). SAINT-Plus (including XPREP). Bruker AXS Inc., Madison, Wisconsin, USA.
  • Bruno, I. J., Cole, J. C., Edgington, P. R., Kessler, M., Macrae, C. F., McCabe, P., Pearson, J. & Taylor, R. (2002). Acta Cryst. B58, 389–397. [PubMed]
  • Farrugia, L. J. (1999). J. Appl. Cryst.32, 837–838.
  • Lemmerer, A. & Billing, D. G. (2006). Acta Cryst. C62, o271–o273. [PubMed]
  • Sharma, C. V. K. & Desiraju, G. R. (1994). J. Chem. Soc. Perkin Trans. 2, pp. 2345–2352.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2003). J. Appl. Cryst.36, 7–13.

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