Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270106011358/gd3015sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270106011358/gd3015Isup2.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270106011358/gd3015IIsup3.hkl |
CCDC references: 609420; 609421
For the preparation of (I), 2-methyl-4-nitroaniline (0.196 g, 1.29 mmol) was added to 48% HBr (18 ml) and the precipitate dissolved by heating the solution. The solution was then cooled to room temperature and yellow crystals of (I) were grown by slow evaporation. Analysis, calculated for C7H9Br1N2O2: C 36.1, H 3.9, N 12.0%; found: C 36.8, H 3.9, N 12.7%.
For the preparation of (II), 2-methyl-4-nitroaniline (0.204 g, 1.34 mmol) was added to 47% HI (1 ml) and the precipitate dissolved with ethanol (10 ml). Yellow crystals of (II) were grown by slow evaporation of the solution mixture. Elemental analysis was not deemed necessary.
H atoms bonded to C and N atoms were refined in idealized positions in the riding-model approximation, with C—H = 0.93 Å and N—H = 0.89 Å, and with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(N). The NH3 group was allowed to rotate but not to tip. The highest residual peak was 1.92 Å from Br1 in (I) and 1.90 Å from I1 in (II).
For both compounds, data collection: SMART (Bruker, 1998); cell refinement: SAINT-Plus (Bruker, 1999); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2003).
C7H9N2O2+·Br− | F(000) = 464 |
Mr = 233.07 | Dx = 1.561 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71069 Å |
Hall symbol: -P 2ybc | Cell parameters from 837 reflections |
a = 14.687 (5) Å | θ = 3.5–26.0° |
b = 9.840 (5) Å | µ = 4.11 mm−1 |
c = 6.877 (5) Å | T = 293 K |
β = 93.836 (5)° | Needle, light yellow |
V = 991.6 (9) Å3 | 0.24 × 0.08 × 0.04 mm |
Z = 4 |
Bruker SMART CCD area-detector diffractometer | 1435 reflections with I > 2σ(I) |
ϕ and ω scans | Rint = 0.027 |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | θmax = 25.3°, θmin = 1.4° |
Tmin = 0.565, Tmax = 0.850 | h = −17→17 |
5290 measured reflections | k = −11→10 |
1798 independent reflections | l = −7→8 |
Refinement on F2 | 92 restraints |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.058 | w = 1/[σ2(Fo2) + (0.1324P)2 + 1.4593P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.220 | (Δ/σ)max = 0.006 |
S = 1.21 | Δρmax = 0.77 e Å−3 |
1798 reflections | Δρmin = −0.96 e Å−3 |
99 parameters |
C7H9N2O2+·Br− | V = 991.6 (9) Å3 |
Mr = 233.07 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 14.687 (5) Å | µ = 4.11 mm−1 |
b = 9.840 (5) Å | T = 293 K |
c = 6.877 (5) Å | 0.24 × 0.08 × 0.04 mm |
β = 93.836 (5)° |
Bruker SMART CCD area-detector diffractometer | 1798 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1435 reflections with I > 2σ(I) |
Tmin = 0.565, Tmax = 0.850 | Rint = 0.027 |
5290 measured reflections |
R[F2 > 2σ(F2)] = 0.058 | 92 restraints |
wR(F2) = 0.220 | H-atom parameters constrained |
S = 1.21 | Δρmax = 0.77 e Å−3 |
1798 reflections | Δρmin = −0.96 e Å−3 |
99 parameters |
Experimental. absorption corrections were made using the program SADABS (Sheldrick, 1996). |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.7034 (4) | 0.4336 (6) | 0.7821 (11) | 0.0741 (18) | |
C2 | 0.7922 (4) | 0.4827 (5) | 0.8056 (10) | 0.0802 (19) | |
C3 | 0.8652 (3) | 0.3925 (7) | 0.8192 (12) | 0.085 (2) | |
H3 | 0.9246 | 0.4253 | 0.8349 | 0.102* | |
C4 | 0.8494 (4) | 0.2534 (7) | 0.8094 (12) | 0.091 (2) | |
C5 | 0.7606 (5) | 0.2043 (5) | 0.7859 (11) | 0.088 (2) | |
H5 | 0.7501 | 0.1112 | 0.7793 | 0.105* | |
C6 | 0.6876 (4) | 0.2945 (7) | 0.7723 (11) | 0.082 (2) | |
H6 | 0.6282 | 0.2616 | 0.7566 | 0.098* | |
C7 | 0.8087 (10) | 0.6328 (13) | 0.817 (3) | 0.107 (4) | |
H7A | 0.8731 | 0.6499 | 0.832 | 0.161* | |
H7B | 0.7798 | 0.6695 | 0.9266 | 0.161* | |
H7C | 0.7837 | 0.6752 | 0.6995 | 0.161* | |
N1 | 0.9253 (9) | 0.1586 (14) | 0.824 (2) | 0.114 (3) | |
N2 | 0.6270 (6) | 0.5220 (11) | 0.7677 (12) | 0.084 (2) | |
H2A | 0.5766 | 0.4751 | 0.7874 | 0.126* | |
H2B | 0.6219 | 0.5592 | 0.6495 | 0.126* | |
H2C | 0.6344 | 0.5872 | 0.8571 | 0.126* | |
O1 | 0.9989 (7) | 0.1994 (15) | 0.891 (2) | 0.163 (4) | |
O2 | 0.9129 (9) | 0.0386 (14) | 0.7755 (18) | 0.157 (4) | |
Br1 | 0.59478 (5) | 0.60735 (7) | 0.26192 (10) | 0.0492 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.074 (3) | 0.084 (3) | 0.065 (4) | 0.004 (3) | 0.011 (4) | 0.003 (4) |
C2 | 0.077 (3) | 0.088 (3) | 0.076 (5) | −0.001 (3) | 0.009 (4) | 0.002 (5) |
C3 | 0.076 (3) | 0.102 (4) | 0.078 (5) | 0.005 (3) | 0.004 (5) | −0.001 (5) |
C4 | 0.092 (3) | 0.097 (4) | 0.083 (5) | 0.015 (3) | 0.009 (4) | 0.002 (5) |
C5 | 0.100 (4) | 0.083 (4) | 0.080 (5) | 0.007 (3) | 0.005 (5) | 0.001 (5) |
C6 | 0.085 (3) | 0.084 (3) | 0.075 (5) | −0.001 (3) | 0.006 (4) | 0.001 (4) |
C7 | 0.095 (7) | 0.090 (4) | 0.137 (11) | −0.008 (4) | 0.005 (8) | 0.003 (7) |
N1 | 0.108 (4) | 0.119 (5) | 0.115 (6) | 0.032 (4) | 0.006 (5) | 0.000 (6) |
N2 | 0.082 (4) | 0.095 (5) | 0.075 (5) | 0.012 (4) | 0.005 (4) | 0.007 (5) |
O1 | 0.095 (5) | 0.194 (9) | 0.197 (11) | 0.027 (6) | −0.005 (7) | 0.010 (9) |
O2 | 0.195 (10) | 0.121 (6) | 0.152 (9) | 0.063 (6) | −0.006 (8) | −0.024 (7) |
Br1 | 0.0581 (6) | 0.0489 (5) | 0.0408 (5) | −0.0089 (3) | 0.0043 (3) | 0.0000 (3) |
C1—C2 | 1.39 | C5—H5 | 0.93 |
C1—C6 | 1.39 | C6—H6 | 0.93 |
C1—N2 | 1.418 (10) | C7—H7A | 0.96 |
C2—C3 | 1.39 | C7—H7B | 0.96 |
C2—C7 | 1.498 (14) | C7—H7C | 0.96 |
C3—C4 | 1.39 | N1—O1 | 1.214 (16) |
C3—H3 | 0.93 | N1—O2 | 1.24 (2) |
C4—C5 | 1.39 | N2—H2A | 0.89 |
C4—N1 | 1.451 (12) | N2—H2B | 0.89 |
C5—C6 | 1.39 | N2—H2C | 0.89 |
C2—C1—C6 | 120 | C1—C6—H6 | 120 |
C2—C1—N2 | 121.8 (6) | C2—C7—H7A | 109.5 |
C6—C1—N2 | 118.2 (6) | C2—C7—H7B | 109.5 |
C1—C2—C3 | 120 | H7A—C7—H7B | 109.5 |
C1—C2—C7 | 119.7 (7) | C2—C7—H7C | 109.5 |
C3—C2—C7 | 120.3 (7) | H7A—C7—H7C | 109.5 |
C4—C3—C2 | 120 | H7B—C7—H7C | 109.5 |
C4—C3—H3 | 120 | O1—N1—O2 | 121.9 (13) |
C2—C3—H3 | 120 | O1—N1—C4 | 118.3 (13) |
C5—C4—C3 | 120 | O2—N1—C4 | 119.7 (12) |
C5—C4—N1 | 119.7 (8) | C1—N2—H2A | 109.5 |
C3—C4—N1 | 120.3 (8) | C1—N2—H2B | 109.5 |
C4—C5—C6 | 120 | H2A—N2—H2B | 109.5 |
C4—C5—H5 | 120 | C1—N2—H2C | 109.5 |
C6—C5—H5 | 120 | H2A—N2—H2C | 109.5 |
C5—C6—C1 | 120 | H2B—N2—H2C | 109.5 |
C5—C6—H6 | 120 | ||
C6—C1—C2—C3 | 0 | N1—C4—C5—C6 | 179.8 (9) |
N2—C1—C2—C3 | 180.0 (7) | C4—C5—C6—C1 | 0 |
C6—C1—C2—C7 | −179.7 (10) | C2—C1—C6—C5 | 0 |
N2—C1—C2—C7 | 0.2 (11) | N2—C1—C6—C5 | −180.0 (7) |
C1—C2—C3—C4 | 0 | C5—C4—N1—O1 | −162.3 (12) |
C7—C2—C3—C4 | 179.7 (10) | C3—C4—N1—O1 | 17.5 (17) |
C2—C3—C4—C5 | 0 | C5—C4—N1—O2 | 15.1 (16) |
C2—C3—C4—N1 | −179.8 (9) | C3—C4—N1—O2 | −165.0 (11) |
C3—C4—C5—C6 | 0 |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···Br1i | 0.89 | 2.64 | 3.490 (10) | 159 |
N2—H2B···Br1 | 0.89 | 2.71 | 3.579 (8) | 165 |
N2—H2C···Br1ii | 0.89 | 2.89 | 3.563 (9) | 134 |
N2—H2C···Br1iii | 0.89 | 3.12 | 3.677 (10) | 122 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x, y, z+1; (iii) x, −y+3/2, z+1/2. |
C7H9N2O2+·I− | F(000) = 536 |
Mr = 280.06 | Dx = 1.88 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 576 reflections |
a = 14.671 (4) Å | θ = 3.5–19.7° |
b = 9.830 (3) Å | µ = 3.20 mm−1 |
c = 6.875 (2) Å | T = 293 K |
β = 93.782 (7)° | Needle, yellow |
V = 989.4 (5) Å3 | 0.14 × 0.06 × 0.03 mm |
Z = 4 |
Bruker SMART CCD area-detector diffractometer | 1047 reflections with I > 2σ(I) |
ϕ and ω scans | Rint = 0.073 |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | θmax = 25.5°, θmin = 1.4° |
Tmin = 0.664, Tmax = 0.911 | h = −15→17 |
5499 measured reflections | k = −11→11 |
1846 independent reflections | l = −8→8 |
Refinement on F2 | 92 restraints |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.070 | w = 1/[σ2(Fo2) + (0.1138P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.187 | (Δ/σ)max = 0.004 |
S = 0.94 | Δρmax = 4.27 e Å−3 |
1846 reflections | Δρmin = −0.85 e Å−3 |
99 parameters |
C7H9N2O2+·I− | V = 989.4 (5) Å3 |
Mr = 280.06 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 14.671 (4) Å | µ = 3.20 mm−1 |
b = 9.830 (3) Å | T = 293 K |
c = 6.875 (2) Å | 0.14 × 0.06 × 0.03 mm |
β = 93.782 (7)° |
Bruker SMART CCD area-detector diffractometer | 1846 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1047 reflections with I > 2σ(I) |
Tmin = 0.664, Tmax = 0.911 | Rint = 0.073 |
5499 measured reflections |
R[F2 > 2σ(F2)] = 0.070 | 92 restraints |
wR(F2) = 0.187 | H-atom parameters constrained |
S = 0.94 | Δρmax = 4.27 e Å−3 |
1846 reflections | Δρmin = −0.85 e Å−3 |
99 parameters |
Experimental. absorption corrections were made using the program SADABS (Sheldrick, 1996). The application of the twin law suggested by PLATON (Version 170106, Spek, 2003) [1 0 0, 0 − 1 0, 0 0 − 1] made no difference to the r-factor or the residual Q-peaks. |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.7037 (4) | 0.4315 (6) | 0.7801 (11) | 0.040 (2) | |
C2 | 0.7928 (5) | 0.4796 (5) | 0.8032 (12) | 0.047 (2) | |
C3 | 0.8655 (4) | 0.3886 (8) | 0.8163 (12) | 0.054 (3) | |
H3 | 0.9251 | 0.4209 | 0.8318 | 0.065* | |
C4 | 0.8490 (4) | 0.2495 (7) | 0.8062 (12) | 0.054 (2) | |
C5 | 0.7599 (5) | 0.2013 (5) | 0.7830 (11) | 0.049 (2) | |
H5 | 0.7489 | 0.1082 | 0.7762 | 0.059* | |
C6 | 0.6872 (4) | 0.2923 (7) | 0.7699 (11) | 0.048 (2) | |
H6 | 0.6276 | 0.2601 | 0.7544 | 0.058* | |
C7 | 0.8118 (10) | 0.6313 (13) | 0.822 (3) | 0.078 (5) | |
H7A | 0.8758 | 0.6477 | 0.8107 | 0.117* | |
H7B | 0.7944 | 0.6629 | 0.9459 | 0.117* | |
H7C | 0.7772 | 0.679 | 0.7196 | 0.117* | |
N1 | 0.9243 (10) | 0.1569 (15) | 0.825 (2) | 0.077 (3) | |
N2 | 0.6273 (6) | 0.5232 (11) | 0.7665 (12) | 0.048 (2) | |
H2A | 0.5756 | 0.4757 | 0.7561 | 0.071* | |
H2B | 0.6307 | 0.5759 | 0.6619 | 0.071* | |
H2C | 0.6283 | 0.5748 | 0.8729 | 0.071* | |
O1 | 0.9969 (8) | 0.1965 (14) | 0.896 (2) | 0.123 (5) | |
O2 | 0.9106 (9) | 0.0396 (14) | 0.7834 (18) | 0.111 (4) | |
I1 | 0.59475 (6) | 0.60749 (8) | 0.26188 (11) | 0.0490 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.042 (4) | 0.048 (4) | 0.033 (6) | 0.001 (3) | 0.011 (5) | 0.001 (5) |
C2 | 0.046 (4) | 0.048 (4) | 0.047 (6) | −0.004 (3) | 0.007 (5) | 0.006 (5) |
C3 | 0.042 (5) | 0.063 (4) | 0.058 (7) | 0.001 (4) | 0.014 (6) | 0.001 (6) |
C4 | 0.059 (4) | 0.056 (4) | 0.047 (6) | 0.010 (4) | 0.010 (6) | 0.004 (6) |
C5 | 0.068 (5) | 0.044 (5) | 0.036 (6) | 0.001 (3) | 0.011 (6) | 0.006 (5) |
C6 | 0.051 (5) | 0.050 (4) | 0.044 (6) | −0.008 (3) | 0.009 (5) | −0.002 (5) |
C7 | 0.061 (9) | 0.054 (5) | 0.119 (13) | −0.009 (5) | 0.004 (9) | 0.000 (8) |
N1 | 0.078 (5) | 0.083 (6) | 0.072 (8) | 0.033 (5) | 0.019 (6) | 0.018 (6) |
N2 | 0.045 (5) | 0.058 (6) | 0.040 (6) | 0.004 (4) | 0.006 (5) | 0.011 (5) |
O1 | 0.066 (6) | 0.135 (10) | 0.168 (14) | 0.029 (6) | 0.008 (7) | 0.023 (9) |
O2 | 0.133 (10) | 0.084 (6) | 0.115 (10) | 0.061 (6) | −0.003 (8) | −0.006 (7) |
I1 | 0.0580 (6) | 0.0466 (5) | 0.0425 (5) | −0.0084 (4) | 0.0053 (4) | 0.0000 (4) |
C1—C2 | 1.39 | C5—H5 | 0.93 |
C1—C6 | 1.39 | C6—H6 | 0.93 |
C1—N2 | 1.436 (10) | C7—H7A | 0.96 |
C2—C3 | 1.39 | C7—H7B | 0.96 |
C2—C7 | 1.521 (13) | C7—H7C | 0.96 |
C3—C4 | 1.39 | N1—O2 | 1.202 (19) |
C3—H3 | 0.93 | N1—O1 | 1.207 (17) |
C4—C5 | 1.39 | N2—H2A | 0.89 |
C4—N1 | 1.431 (13) | N2—H2B | 0.89 |
C5—C6 | 1.39 | N2—H2C | 0.89 |
C2—C1—C6 | 120 | C1—C6—H6 | 120 |
C2—C1—N2 | 121.2 (6) | C2—C7—H7A | 109.5 |
C6—C1—N2 | 118.8 (6) | C2—C7—H7B | 109.5 |
C1—C2—C3 | 120 | H7A—C7—H7B | 109.5 |
C1—C2—C7 | 120.6 (7) | C2—C7—H7C | 109.5 |
C3—C2—C7 | 119.4 (7) | H7A—C7—H7C | 109.5 |
C4—C3—C2 | 120 | H7B—C7—H7C | 109.5 |
C4—C3—H3 | 120 | O2—N1—O1 | 122.4 (14) |
C2—C3—H3 | 120 | O2—N1—C4 | 118.2 (14) |
C3—C4—C5 | 120 | O1—N1—C4 | 119.1 (14) |
C3—C4—N1 | 119.4 (8) | C1—N2—H2A | 109.5 |
C5—C4—N1 | 120.6 (8) | C1—N2—H2B | 109.5 |
C4—C5—C6 | 120 | H2A—N2—H2B | 109.5 |
C4—C5—H5 | 120 | C1—N2—H2C | 109.5 |
C6—C5—H5 | 120 | H2A—N2—H2C | 109.5 |
C5—C6—C1 | 120 | H2B—N2—H2C | 109.5 |
C5—C6—H6 | 120 | ||
C6—C1—C2—C3 | 0 | N1—C4—C5—C6 | 178.3 (9) |
N2—C1—C2—C3 | 179.9 (8) | C4—C5—C6—C1 | 0 |
C6—C1—C2—C7 | −177.9 (10) | C2—C1—C6—C5 | 0 |
N2—C1—C2—C7 | 2.0 (11) | N2—C1—C6—C5 | −179.9 (8) |
C1—C2—C3—C4 | 0 | C3—C4—N1—O2 | −167.6 (11) |
C7—C2—C3—C4 | 177.9 (10) | C5—C4—N1—O2 | 14.0 (16) |
C2—C3—C4—C5 | 0 | C3—C4—N1—O1 | 18.3 (17) |
C2—C3—C4—N1 | −178.4 (9) | C5—C4—N1—O1 | −160.0 (12) |
C3—C4—C5—C6 | 0 |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···I1i | 0.89 | 2.62 | 3.495 (10) | 166 |
N2—H2C···I1ii | 0.89 | 2.77 | 3.568 (9) | 150 |
N2—H2B···I1 | 0.89 | 2.78 | 3.568 (8) | 148 |
N2—H2B···I1iii | 0.89 | 3.24 | 3.662 (10) | 112 |
N2—H2C···I1iii | 0.89 | 3.24 | 3.662 (10) | 112 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x, y, z+1; (iii) x, −y+3/2, z+1/2. |
Experimental details
(I) | (II) | |
Crystal data | ||
Chemical formula | C7H9N2O2+·Br− | C7H9N2O2+·I− |
Mr | 233.07 | 280.06 |
Crystal system, space group | Monoclinic, P21/c | Monoclinic, P21/c |
Temperature (K) | 293 | 293 |
a, b, c (Å) | 14.687 (5), 9.840 (5), 6.877 (5) | 14.671 (4), 9.830 (3), 6.875 (2) |
β (°) | 93.836 (5) | 93.782 (7) |
V (Å3) | 991.6 (9) | 989.4 (5) |
Z | 4 | 4 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 4.11 | 3.20 |
Crystal size (mm) | 0.24 × 0.08 × 0.04 | 0.14 × 0.06 × 0.03 |
Data collection | ||
Diffractometer | Bruker SMART CCD area-detector diffractometer | Bruker SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.565, 0.850 | 0.664, 0.911 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5290, 1798, 1435 | 5499, 1846, 1047 |
Rint | 0.027 | 0.073 |
(sin θ/λ)max (Å−1) | 0.600 | 0.606 |
Refinement | ||
R[F2 > 2σ(F2)], wR(F2), S | 0.058, 0.220, 1.21 | 0.070, 0.187, 0.94 |
No. of reflections | 1798 | 1846 |
No. of parameters | 99 | 99 |
No. of restraints | 92 | 92 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.77, −0.96 | 4.27, −0.85 |
Computer programs: SMART (Bruker, 1998), SAINT-Plus (Bruker, 1999), SAINT-Plus, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg, 1999), WinGX (Farrugia, 1999) and PLATON (Spek, 2003).
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···Br1i | 0.89 | 2.64 | 3.490 (10) | 159 |
N2—H2B···Br1 | 0.89 | 2.71 | 3.579 (8) | 165 |
N2—H2C···Br1ii | 0.89 | 2.89 | 3.563 (9) | 134 |
N2—H2C···Br1iii | 0.89 | 3.12 | 3.677 (10) | 122 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x, y, z+1; (iii) x, −y+3/2, z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···I1i | 0.89 | 2.62 | 3.495 (10) | 166 |
N2—H2C···I1ii | 0.89 | 2.77 | 3.568 (9) | 150 |
N2—H2B···I1 | 0.89 | 2.78 | 3.568 (8) | 148 |
N2—H2B···I1iii | 0.89 | 3.24 | 3.662 (10) | 112 |
N2—H2C···I1iii | 0.89 | 3.24 | 3.662 (10) | 112 |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x, y, z+1; (iii) x, −y+3/2, z+1/2. |
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As part of a study of the effect of anions on the crystal structures of anilinium halide salts, the crystal structures of two protonated 2-methyl-4-nitroaniline molecules are reported. The unprotonated case, O2NC7H6NH2, has been studied previously (Ferguson et al., 2001). The authors were investigating the effect that the substituents on the ring had on the packing arrangement and the hydrogen bonding, and they found that the molecules act as double donors and double acceptors of N—H···O hydrogen bonds. The introduction of a halide anion has a significant effect on the packing, as the ammonium groups form N—H···X hydrogen bonds only in the title compounds. We report here the isostructural salts 2-methyl-4-nitroanilinium bromide, (I), and 2-methyl-4-nitroanilinium iodide, (II). The detailed packing of (I) will be discussed, as well as the hydrogen bonding of (II).
The atomic numbering schemes of both compounds are shown in Fig. 1. Fig. 2 shows the one-dimensional arrangement of (I), in which a single layer of cations is embedded between two ionic layers, forming an alternating hydrocarbon–ionic structure. Within the ionic layer, the Br− atoms and ammonium groups interact via hydrogen bonds. The cations pack head-to-head in layers parallel to the ab plane. In contrast, the unsubstituted 4-nitroanilinium bromide has a head-to-tail packing arrangement (Lemmerer & Billing, 2006).
Compound (II) has the same packing arrangement as (I) but differs only in the identity of the counterion, I1. The volume of the unit cell is unexpectedly less by 2.2 Å3 for the iodide case, even though the I− ion has a larger ionic radius (2.20 Å) than bromide (1.96 Å) (Reference for standard values?). To compensate, the cations pack closer together.
Compound (II) has an extensive network of hydrogen bonding. In the crystal structure, the ions are linked together by N2—H2C···I1···H2B—N2—H2C···I1 hydrogen bonds, forming infinite chains parallel to [001]. At the same time, two adjacent chains are linked in the [100] direction by N2—H2A···I1 hydrogen bonds to form a connected set of infinite chains (Fig. 3). Overall, the hydrogen-bonding scheme is R22(8) (Bernstein et al., 1995). The hydrogen-bonded rings connect I− ions and 2-methyl-4-nitroanilinium cations, which are related by a twofold screw axis. The chains form ladders, which are parallel to the ac plane. These ladders are then stacked perpendicular to this plane and are connected to the I− ions of adjacent ladders by I1···H2C—N2—H2B···I1 hydrogen bonds, i.e. atoms H2C and H2B have bifurcated hydrogen bonds. These interactions are weaker, as the hydrogen-acceptor distances are 3.245 (1) and 3.238 (1) Å.
Compound (I) has the same hydrogen-bonding sequence in the c direction. However, due to the smaller van der Waals radius of Br, the ladders are connected by a single Br1···H2C—N2 hydrogen bond. The hydrogen-acceptor distance is 3.12 Å. Subsequently, there is only one bifurcated and three simple hydrogen bonds in (I), compared with three simple and two bifurcated hydrogen bonds in (II).