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2-Chloro-4-nitrobenzoic acid and 2-chloro-5-nitrobenzoic acid form O—H
N hydrogen bonds with pyrazine to afford 2:1 complexes of 2C
7H
4ClNO
4·C
4H
4N
2, (I) and (II), respectively, that are located on inversion centers. The 2C
7H
4ClNO
4·C
4H
4N
2 units in both complexes are connected by weak C—H
O hydrogen bonds; the units build a three-dimensional hydrogen-bond network in (I) and a ribbon structure in (II).
Supporting information
CCDC references: 169962; 169963
The prismatic crystals of (I) and (II) were obtained by slow evaporation from
benzene solutions of pyrazine with 2-chloro-4-nitrobenzoic acid or
2-chloro-5-nitrobenzoic acid (molar ratio 2:1) at room temperature.
H atoms were found in a difference Fourier map and refined isotropically.
Refined distances: C—H = 0.896–0.99 and O—H = 0.84 Å for (I), and C—H
= 0.951–1.00 and O—H = 1.00 Å for (II).
For both compounds, data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1990); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN for Windows (Molecular Structure Corporation, 1997-1999). Program(s) used to solve structure: SIR92 (Altomare et al., 1993) for (I); SAPI90 (Fan, 1990) for (II). For both compounds, program(s) used to refine structure: TEXSAN for Windows; software used to prepare material for publication: TEXSAN for Windows.
Crystal data top
C4H4N2·2C7H4ClNO4 | F(000) = 492 |
Mr = 483.22 | Dx = 1.548 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
a = 3.8280 (5) Å | Cell parameters from 25 reflections |
b = 12.7738 (16) Å | θ = 11.1–12.4° |
c = 21.203 (3) Å | µ = 0.37 mm−1 |
β = 91.118 (14)° | T = 296 K |
V = 1036.6 (2) Å3 | Prismatic, colorless |
Z = 2 | 0.40 × 0.30 × 0.30 mm |
Data collection top
Rigaku AFC5R diffractometer | 1275 reflections with I > 2.0σ(I) |
Radiation source: Rigaku rotating anode | Rint = 0.031 |
Graphite monochromator | θmax = 27.5°, θmin = 1.6° |
ω–2θ scans | h = −1→4 |
Absorption correction: ψ scans (North et al., 1968) | k = 0→16 |
Tmin = 0.862, Tmax = 0.895 | l = −27→27 |
3559 measured reflections | 3 standard reflections every 97 reflections |
2477 independent reflections | intensity decay: 1.6% |
Refinement top
Refinement on F2 | 0 restraints |
Least-squares matrix: full | 0 constraints |
R[F2 > 2σ(F2)] = 0.057 | All H-atom parameters refined |
wR(F2) = 0.063 | Weighting scheme based on measured s.u.'s w = 1/[σ2(Fo) + 0.00003|Fo|2] |
S = 1.38 | (Δ/σ)max = 0.01 |
2360 reflections | Δρmax = 0.39 e Å−3 |
169 parameters | Δρmin = −0.49 e Å−3 |
Crystal data top
C4H4N2·2C7H4ClNO4 | V = 1036.6 (2) Å3 |
Mr = 483.22 | Z = 2 |
Monoclinic, P21/n | Mo Kα radiation |
a = 3.8280 (5) Å | µ = 0.37 mm−1 |
b = 12.7738 (16) Å | T = 296 K |
c = 21.203 (3) Å | 0.40 × 0.30 × 0.30 mm |
β = 91.118 (14)° | |
Data collection top
Rigaku AFC5R diffractometer | 1275 reflections with I > 2.0σ(I) |
Absorption correction: ψ scans (North et al., 1968) | Rint = 0.031 |
Tmin = 0.862, Tmax = 0.895 | 3 standard reflections every 97 reflections |
3559 measured reflections | intensity decay: 1.6% |
2477 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.057 | 0 restraints |
wR(F2) = 0.063 | All H-atom parameters refined |
S = 1.38 | Δρmax = 0.39 e Å−3 |
2360 reflections | Δρmin = −0.49 e Å−3 |
169 parameters | |
Special details top
Experimental. The scan width was (1.31 + 0.30tanθ)° with an ω scan speed of 6° per minute
(up to 3 scans to achieve I/σ(I) > 10). Stationary background counts were
recorded at each end of the scan, and the scan time:background time ratio was
2:1. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Cl | 0.38589 (16) | 0.65568 (5) | 0.18102 (3) | 0.0650 (2) | |
O1 | 0.2745 (5) | 0.41390 (14) | 0.32294 (8) | 0.0704 (6) | |
O2 | 0.4581 (5) | 0.57765 (14) | 0.31430 (8) | 0.0900 (7) | |
O3 | 0.7819 (6) | 0.40493 (17) | 0.00424 (9) | 0.1141 (9) | |
O4 | 1.0445 (5) | 0.27749 (14) | 0.04790 (8) | 0.0950 (8) | |
N1 | 0.8701 (6) | 0.35573 (17) | 0.05023 (9) | 0.0637 (8) | |
N2 | 0.0822 (5) | 0.46729 (16) | 0.43978 (9) | 0.0572 (7) | |
C1 | 0.5269 (5) | 0.45966 (17) | 0.22771 (10) | 0.0444 (7) | |
C2 | 0.5288 (5) | 0.52768 (15) | 0.17643 (10) | 0.0450 (7) | |
C3 | 0.6393 (6) | 0.49367 (18) | 0.11818 (11) | 0.0499 (8) | |
C4 | 0.7520 (5) | 0.39189 (17) | 0.11241 (10) | 0.0475 (7) | |
C5 | 0.7579 (6) | 0.32239 (18) | 0.16191 (11) | 0.0519 (8) | |
C6 | 0.6388 (6) | 0.35739 (18) | 0.21922 (11) | 0.0505 (8) | |
C7 | 0.4168 (6) | 0.49255 (19) | 0.29238 (11) | 0.0549 (8) | |
C8 | 0.0792 (8) | 0.5669 (2) | 0.45539 (13) | 0.0721 (10) | |
C9 | 0.0007 (8) | 0.5995 (2) | 0.51499 (13) | 0.0738 (10) | |
H1 | 0.216 (7) | 0.434 (2) | 0.3588 (13) | 0.135 (11)* | |
H2 | 0.629 (5) | 0.5377 (13) | 0.0853 (8) | 0.044 (6)* | |
H3 | 0.833 (5) | 0.2524 (16) | 0.1561 (9) | 0.069 (7)* | |
H4 | 0.633 (4) | 0.3070 (14) | 0.2545 (8) | 0.048 (6)* | |
H5 | 0.134 (6) | 0.6151 (18) | 0.4241 (10) | 0.093 (9)* | |
H6 | −0.019 (6) | 0.6703 (18) | 0.5264 (11) | 0.094 (9)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cl | 0.0778 (5) | 0.0432 (3) | 0.0743 (4) | 0.0124 (4) | 0.0084 (3) | −0.0066 (3) |
O1 | 0.0996 (14) | 0.0639 (11) | 0.0485 (11) | −0.0191 (10) | 0.0234 (10) | −0.0047 (10) |
O2 | 0.1423 (18) | 0.0617 (12) | 0.0675 (13) | −0.0312 (12) | 0.0375 (12) | −0.0219 (10) |
O3 | 0.171 (2) | 0.1232 (17) | 0.0492 (12) | 0.0631 (15) | 0.0201 (13) | 0.0047 (12) |
O4 | 0.1302 (18) | 0.0785 (14) | 0.0772 (14) | 0.0403 (13) | 0.0230 (12) | −0.0206 (11) |
N1 | 0.0760 (16) | 0.0631 (15) | 0.0523 (14) | 0.0077 (13) | 0.0100 (12) | −0.0124 (12) |
N2 | 0.0648 (14) | 0.0614 (14) | 0.0460 (12) | −0.0082 (11) | 0.0142 (10) | 0.0028 (11) |
C1 | 0.0454 (15) | 0.0454 (13) | 0.0426 (14) | −0.0058 (11) | 0.0073 (11) | −0.0026 (11) |
C2 | 0.0450 (14) | 0.0378 (12) | 0.0522 (15) | −0.0003 (10) | 0.0064 (11) | −0.0075 (11) |
C3 | 0.0569 (16) | 0.0459 (14) | 0.0469 (16) | 0.0050 (12) | 0.0047 (12) | 0.0073 (12) |
C4 | 0.0505 (15) | 0.0505 (14) | 0.0417 (13) | 0.0034 (12) | 0.0078 (11) | −0.0070 (12) |
C5 | 0.0613 (17) | 0.0402 (14) | 0.0544 (16) | 0.0047 (12) | 0.0024 (13) | −0.0031 (12) |
C6 | 0.0597 (16) | 0.0456 (15) | 0.0462 (15) | −0.0035 (12) | 0.0041 (12) | 0.0041 (12) |
C7 | 0.0598 (17) | 0.0575 (16) | 0.0478 (16) | −0.0075 (14) | 0.0098 (13) | −0.0046 (13) |
C8 | 0.107 (2) | 0.0611 (19) | 0.0490 (18) | −0.0130 (16) | 0.0204 (16) | 0.0107 (14) |
C9 | 0.109 (2) | 0.0562 (18) | 0.0573 (19) | −0.0067 (18) | 0.0215 (17) | 0.0013 (16) |
Geometric parameters (Å, º) top
Cl—C2 | 1.727 (2) | C1—C7 | 1.502 (3) |
O1—C7 | 1.319 (3) | C2—C3 | 1.383 (3) |
O1—H1 | 0.84 (3) | C3—C4 | 1.376 (3) |
O2—C7 | 1.191 (3) | C3—H2 | 0.896 (19) |
O3—N1 | 1.203 (3) | C4—C5 | 1.375 (3) |
O4—N1 | 1.204 (3) | C5—C6 | 1.380 (3) |
N1—C4 | 1.476 (3) | C5—H3 | 0.95 (2) |
N2—C8 | 1.315 (3) | C6—H4 | 0.99 (2) |
N2—C9i | 1.327 (3) | C8—C9 | 1.370 (4) |
C1—C2 | 1.392 (3) | C8—H5 | 0.93 (3) |
C1—C6 | 1.388 (3) | C9—H6 | 0.94 (3) |
| | | |
O1···N2 | 2.686 (3) | O3···O3v | 3.252 (5) |
O1···C6ii | 3.327 (3) | O3···C3v | 3.294 (4) |
O2···C5iii | 3.345 (3) | O4···C8vi | 3.053 (4) |
O2···C8 | 3.352 (4) | O4···C9vi | 3.173 (4) |
O3···O3iv | 2.955 (6) | O4···N1vii | 3.314 (4) |
| | | |
C7—O1—H1 | 109 (2) | C3—C4—C5 | 122.9 (3) |
O3—N1—O4 | 123.2 (3) | C4—C5—C6 | 117.5 (3) |
O3—N1—C4 | 118.3 (3) | C4—C5—H3 | 120.7 (15) |
O4—N1—C4 | 118.5 (3) | C6—C5—H3 | 121.7 (15) |
C8—N2—C9i | 115.9 (3) | C1—C6—C5 | 121.8 (3) |
C2—C1—C6 | 118.7 (2) | C1—C6—H4 | 120.3 (12) |
C2—C1—C7 | 123.0 (2) | C5—C6—H4 | 117.9 (12) |
C6—C1—C7 | 118.3 (2) | O1—C7—O2 | 123.8 (3) |
Cl—C2—C1 | 122.71 (19) | O1—C7—C1 | 111.2 (2) |
Cl—C2—C3 | 116.8 (2) | O2—C7—C1 | 125.0 (3) |
C1—C2—C3 | 120.5 (2) | N2—C8—C9 | 122.0 (3) |
C2—C3—C4 | 118.6 (3) | N2—C8—H5 | 117.2 (17) |
C2—C3—H2 | 119.2 (14) | C9—C8—H5 | 120.8 (17) |
C4—C3—H2 | 122.2 (14) | N2—C9i—C8i | 122.1 (3) |
N1—C4—C3 | 118.5 (2) | N2—C9i—H6i | 114.4 (18) |
N1—C4—C5 | 118.6 (2) | C8—C9—H6 | 123.3 (18) |
| | | |
Cl—C2—C1—C6 | 178.5 (2) | N1—C4—C3—C2 | −180.0 (2) |
Cl—C2—C1—C7 | −3.0 (4) | N1—C4—C5—C6 | −178.6 (2) |
Cl—C2—C3—C4 | −179.4 (2) | C1—C2—C3—C4 | −1.0 (4) |
O1—C7—C1—C2 | 149.1 (3) | C1—C6—C5—C4 | −2.0 (4) |
O1—C7—C1—C6 | −32.4 (4) | C2—C1—C6—C5 | 1.4 (4) |
O2—C7—C1—C2 | −32.5 (4) | C2—C3—C4—C5 | 0.3 (4) |
O2—C7—C1—C6 | 146.1 (3) | C3—C2—C1—C6 | 0.2 (4) |
O3—N1—C4—C3 | −19.0 (4) | C3—C2—C1—C7 | 178.7 (3) |
O3—N1—C4—C5 | 160.7 (3) | C3—C4—C5—C6 | 1.2 (4) |
O4—N1—C4—C3 | 162.3 (3) | C5—C6—C1—C7 | −177.2 (3) |
O4—N1—C4—C5 | −18.0 (4) | | |
Symmetry codes: (i) −x, −y+1, −z+1; (ii) x−1, y, z; (iii) −x+3/2, y+1/2, −z+1/2; (iv) −x+2, −y+1, −z; (v) −x+1, −y+1, −z; (vi) −x+3/2, y−1/2, −z+1/2; (vii) x+1, y, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···N2 | 0.84 (3) | 1.85 (3) | 2.686 (3) | 175 (3) |
C3—H2···O3v | 0.90 (2) | 2.55 (2) | 3.294 (4) | 141 (2) |
C5—H3···O2vi | 0.95 (2) | 2.45 (2) | 3.345 (3) | 158 (2) |
C8—H5···O4iii | 0.93 (3) | 2.48 (3) | 3.053 (4) | 120 (2) |
Symmetry codes: (iii) −x+3/2, y+1/2, −z+1/2; (v) −x+1, −y+1, −z; (vi) −x+3/2, y−1/2, −z+1/2. |
Crystal data top
C4H4N2·2C7H4ClNO4 | F(000) = 492 |
Mr = 483.22 | Dx = 1.606 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 10.293 (4) Å | Cell parameters from 25 reflections |
b = 7.276 (2) Å | θ = 10.0–12.5° |
c = 13.818 (6) Å | µ = 0.38 mm−1 |
β = 105.17 (3)° | T = 293 K |
V = 998.9 (6) Å3 | Prismatic, colorless |
Z = 2 | 0.40 × 0.30 × 0.20 mm |
Data collection top
Rigaku AFC5R diffractometer | 1268 reflections with I > 2.0σ(I) |
Radiation source: Rigaku rotating anode | Rint = 0.039 |
Graphite monochromator | θmax = 27.5°, θmin = 1.5° |
ω–2θ scans | h = −1→13 |
Absorption correction: ψ scans (North et al., 1968) | k = 0→9 |
Tmin = 0.810, Tmax = 0.926 | l = −17→17 |
2887 measured reflections | 3 standard reflections every 97 reflections |
2293 independent reflections | intensity decay: 1.6% |
Refinement top
Refinement on F2 | 0 constraints |
Least-squares matrix: full | All H-atom parameters refined |
R[F2 > 2σ(F2)] = 0.051 | Weighting scheme based on measured s.u.'s w = 1/[σ2(Fo) + 0.00001|Fo|2] |
wR(F2) = 0.061 | (Δ/σ)max = 0.01 |
S = 1.33 | Δρmax = 0.44 e Å−3 |
2292 reflections | Δρmin = −0.61 e Å−3 |
170 parameters | Extinction correction: Zachariasen (1967), equ(3) Acta Cryst.(1968) A24, p213. |
0 restraints | Extinction coefficient: 2.48 (9)×10-6 |
Crystal data top
C4H4N2·2C7H4ClNO4 | V = 998.9 (6) Å3 |
Mr = 483.22 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 10.293 (4) Å | µ = 0.38 mm−1 |
b = 7.276 (2) Å | T = 293 K |
c = 13.818 (6) Å | 0.40 × 0.30 × 0.20 mm |
β = 105.17 (3)° | |
Data collection top
Rigaku AFC5R diffractometer | 1268 reflections with I > 2.0σ(I) |
Absorption correction: ψ scans (North et al., 1968) | Rint = 0.039 |
Tmin = 0.810, Tmax = 0.926 | 3 standard reflections every 97 reflections |
2887 measured reflections | intensity decay: 1.6% |
2293 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.051 | 0 restraints |
wR(F2) = 0.061 | All H-atom parameters refined |
S = 1.33 | Δρmax = 0.44 e Å−3 |
2292 reflections | Δρmin = −0.61 e Å−3 |
170 parameters | |
Special details top
Experimental. The scan width was (1.52 + 0.30tanθ)° with an ω scan speed of 6° per minute
(up to 3 scans to achieve I/σ(I) > 10). Stationary background counts were
recorded at each end of the scan, and the scan time:background time ratio was
2:1. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Cl | 0.02826 (7) | 0.10612 (10) | 0.27895 (5) | 0.0535 (2) | |
O1 | 0.12332 (17) | 0.3384 (3) | 0.00595 (13) | 0.0590 (7) | |
O2 | 0.20442 (16) | 0.2408 (3) | 0.16189 (13) | 0.0633 (6) | |
O3 | −0.45413 (17) | 0.0651 (3) | −0.14017 (13) | 0.0761 (7) | |
O4 | −0.30575 (18) | 0.2081 (3) | −0.19589 (13) | 0.0734 (7) | |
N1 | −0.3433 (2) | 0.1338 (3) | −0.12914 (15) | 0.0523 (8) | |
N2 | 0.37543 (19) | 0.4335 (3) | 0.00226 (16) | 0.0503 (7) | |
C1 | −0.0288 (2) | 0.1914 (3) | 0.07882 (16) | 0.0318 (7) | |
C2 | −0.0734 (2) | 0.1155 (3) | 0.15764 (16) | 0.0344 (7) | |
C3 | −0.2028 (3) | 0.0470 (4) | 0.14345 (19) | 0.0438 (9) | |
C4 | −0.2909 (2) | 0.0510 (4) | 0.04937 (18) | 0.0429 (8) | |
C5 | −0.2489 (2) | 0.1275 (3) | −0.02785 (16) | 0.0368 (7) | |
C6 | −0.1211 (2) | 0.1962 (3) | −0.01528 (17) | 0.0359 (8) | |
C7 | 0.1126 (2) | 0.2608 (4) | 0.08890 (18) | 0.0388 (8) | |
C8 | 0.4022 (3) | 0.4841 (4) | −0.0834 (2) | 0.0559 (10) | |
C9 | 0.4738 (3) | 0.4488 (4) | 0.0859 (2) | 0.0522 (9) | |
H1 | 0.218 (3) | 0.372 (4) | 0.010 (2) | 0.113 (11)* | |
H2 | −0.228 (2) | −0.001 (3) | 0.2005 (14) | 0.046 (7)* | |
H3 | −0.3819 (18) | 0.004 (3) | 0.0371 (14) | 0.039 (7)* | |
H4 | −0.0982 (17) | 0.250 (3) | −0.0713 (13) | 0.018 (5)* | |
H5 | 0.335 (2) | 0.469 (3) | −0.1431 (15) | 0.046 (7)* | |
H6 | 0.4542 (19) | 0.414 (3) | 0.1505 (14) | 0.040 (6)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cl | 0.0531 (4) | 0.0694 (5) | 0.0341 (3) | −0.0077 (4) | 0.0045 (3) | 0.0039 (4) |
O1 | 0.0318 (11) | 0.0914 (17) | 0.0534 (12) | −0.0155 (11) | 0.0104 (9) | 0.0172 (11) |
O2 | 0.0355 (10) | 0.1071 (18) | 0.0424 (10) | −0.0106 (11) | 0.0018 (8) | −0.0016 (12) |
O3 | 0.0356 (11) | 0.125 (2) | 0.0604 (13) | −0.0259 (13) | −0.0003 (9) | 0.0014 (14) |
O4 | 0.0600 (14) | 0.1105 (19) | 0.0428 (11) | −0.0215 (13) | 0.0013 (10) | 0.0148 (12) |
N1 | 0.0419 (14) | 0.0687 (19) | 0.0431 (13) | −0.0010 (13) | 0.0053 (11) | −0.0028 (13) |
N2 | 0.0343 (12) | 0.0613 (18) | 0.0567 (14) | −0.0073 (12) | 0.0146 (11) | 0.0052 (14) |
C1 | 0.0324 (13) | 0.0323 (15) | 0.0328 (13) | 0.0006 (12) | 0.0122 (10) | −0.0059 (12) |
C2 | 0.0373 (14) | 0.0333 (16) | 0.0311 (12) | 0.0012 (13) | 0.0062 (10) | −0.0058 (13) |
C3 | 0.0437 (16) | 0.048 (2) | 0.0432 (15) | −0.0046 (14) | 0.0187 (13) | 0.0034 (14) |
C4 | 0.0320 (15) | 0.052 (2) | 0.0453 (15) | −0.0062 (14) | 0.0118 (12) | 0.0026 (14) |
C5 | 0.0321 (13) | 0.0408 (17) | 0.0359 (13) | 0.0017 (13) | 0.0062 (10) | −0.0001 (13) |
C6 | 0.0383 (15) | 0.0368 (17) | 0.0346 (14) | −0.0016 (13) | 0.0130 (12) | −0.0008 (13) |
C7 | 0.0376 (15) | 0.0395 (17) | 0.0420 (15) | −0.0059 (13) | 0.0151 (12) | −0.0094 (14) |
C8 | 0.0411 (18) | 0.077 (3) | 0.0458 (17) | −0.0088 (16) | 0.0041 (14) | 0.0007 (17) |
C9 | 0.0420 (16) | 0.069 (2) | 0.0469 (17) | −0.0024 (16) | 0.0139 (13) | 0.0089 (17) |
Geometric parameters (Å, º) top
Cl—C2 | 1.730 (3) | C1—C7 | 1.512 (3) |
O1—C7 | 1.308 (3) | C2—C3 | 1.387 (4) |
O1—H1 | 1.00 (3) | C3—C4 | 1.377 (4) |
O2—C7 | 1.197 (3) | C3—H2 | 0.96 (2) |
O3—N1 | 1.218 (3) | C4—C5 | 1.370 (4) |
O4—N1 | 1.216 (3) | C4—H3 | 0.97 (2) |
N1—C5 | 1.481 (3) | C5—C6 | 1.375 (3) |
N2—C8 | 1.335 (3) | C6—H4 | 0.951 (19) |
N2—C9 | 1.327 (4) | C8—C9i | 1.376 (4) |
C1—C2 | 1.401 (3) | C8—H5 | 0.93 (2) |
C1—C6 | 1.396 (3) | C9—H6 | 1.00 (2) |
| | | |
O1···N2 | 2.699 (3) | O3···C4iv | 3.301 (4) |
O1···C6ii | 3.389 (4) | O4···C3v | 3.234 (4) |
O2···N1iii | 3.165 (4) | O4···C8vi | 3.371 (4) |
O2···C5iii | 3.357 (4) | C5···C7iii | 3.359 (4) |
| | | |
C7—O1—H1 | 111.3 (18) | C5—C4—H3 | 119.7 (13) |
O3—N1—O4 | 124.1 (3) | N1—C5—C4 | 119.1 (3) |
O3—N1—C5 | 117.8 (3) | N1—C5—C6 | 118.5 (3) |
O4—N1—C5 | 118.1 (2) | C4—C5—C6 | 122.4 (3) |
C8—N2—C9 | 117.5 (3) | C1—C6—C5 | 120.3 (3) |
C2—C1—C6 | 116.9 (3) | C1—C6—H4 | 121.1 (12) |
C2—C1—C7 | 124.3 (2) | C5—C6—H4 | 118.6 (12) |
C6—C1—C7 | 118.8 (2) | O1—C7—O2 | 124.2 (3) |
Cl—C2—C1 | 122.0 (2) | O1—C7—C1 | 111.3 (2) |
Cl—C2—C3 | 116.0 (2) | O2—C7—C1 | 124.5 (3) |
C1—C2—C3 | 122.0 (3) | N2—C8—C9i | 121.9 (3) |
C2—C3—C4 | 119.8 (3) | N2—C8—H5 | 118.5 (16) |
C2—C3—H2 | 118.3 (15) | C9—C8i—H5i | 119.5 (16) |
C4—C3—H2 | 121.9 (15) | N2—C9—C8i | 120.6 (3) |
C3—C4—C5 | 118.6 (3) | N2—C9—H6 | 118.1 (13) |
C3—C4—H3 | 121.6 (13) | C8—C9i—H6i | 121.3 (13) |
| | | |
Cl—C2—C1—C6 | −178.2 (2) | N1—C5—C4—C3 | −179.5 (3) |
Cl—C2—C1—C7 | 4.1 (4) | N1—C5—C6—C1 | −179.5 (3) |
Cl—C2—C3—C4 | 179.3 (3) | C1—C2—C3—C4 | 0.7 (5) |
O1—C7—C1—C2 | −174.6 (3) | C1—C6—C5—C4 | −0.6 (5) |
O1—C7—C1—C6 | 7.7 (4) | C2—C1—C6—C5 | −0.4 (4) |
O2—C7—C1—C2 | 8.1 (5) | C2—C3—C4—C5 | −1.6 (5) |
O2—C7—C1—C6 | −169.5 (3) | C3—C2—C1—C6 | 0.4 (4) |
O3—N1—C5—C4 | −2.1 (4) | C3—C2—C1—C7 | −177.3 (3) |
O3—N1—C5—C6 | 176.8 (3) | C3—C4—C5—C6 | 1.6 (5) |
O4—N1—C5—C4 | 177.4 (3) | C5—C6—C1—C7 | 177.4 (3) |
O4—N1—C5—C6 | −3.7 (4) | | |
Symmetry codes: (i) −x+1, −y+1, −z; (ii) −x, −y+1, −z; (iii) −x, −y, −z; (iv) −x−1, −y, −z; (v) x, −y+1/2, z−1/2; (vi) −x, y−1/2, −z−1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···N2 | 1.00 (3) | 1.71 (3) | 2.699 (3) | 173 (3) |
C3—H2···O2vii | 0.96 (2) | 2.64 (2) | 3.496 (4) | 149 (2) |
C4—H3···O3iv | 0.97 (2) | 2.53 (2) | 3.301 (4) | 137 (2) |
Symmetry codes: (iv) −x−1, −y, −z; (vii) −x, y−1/2, −z+1/2. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | C4H4N2·2C7H4ClNO4 | C4H4N2·2C7H4ClNO4 |
Mr | 483.22 | 483.22 |
Crystal system, space group | Monoclinic, P21/n | Monoclinic, P21/c |
Temperature (K) | 296 | 293 |
a, b, c (Å) | 3.8280 (5), 12.7738 (16), 21.203 (3) | 10.293 (4), 7.276 (2), 13.818 (6) |
β (°) | 91.118 (14) | 105.17 (3) |
V (Å3) | 1036.6 (2) | 998.9 (6) |
Z | 2 | 2 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.37 | 0.38 |
Crystal size (mm) | 0.40 × 0.30 × 0.30 | 0.40 × 0.30 × 0.20 |
|
Data collection |
Diffractometer | Rigaku AFC5R diffractometer | Rigaku AFC5R diffractometer |
Absorption correction | ψ scans (North et al., 1968) | ψ scans (North et al., 1968) |
Tmin, Tmax | 0.862, 0.895 | 0.810, 0.926 |
No. of measured, independent and observed [I > 2.0σ(I)] reflections | 3559, 2477, 1275 | 2887, 2293, 1268 |
Rint | 0.031 | 0.039 |
(sin θ/λ)max (Å−1) | 0.649 | 0.649 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.057, 0.063, 1.38 | 0.051, 0.061, 1.33 |
No. of reflections | 2360 | 2292 |
No. of parameters | 169 | 170 |
H-atom treatment | All H-atom parameters refined | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.39, −0.49 | 0.44, −0.61 |
Selected bond lengths (Å) for (I) topCl—C2 | 1.727 (2) | C1—C2 | 1.392 (3) |
O1—C7 | 1.319 (3) | C1—C6 | 1.388 (3) |
O2—C7 | 1.191 (3) | C1—C7 | 1.502 (3) |
O3—N1 | 1.203 (3) | C2—C3 | 1.383 (3) |
O4—N1 | 1.204 (3) | C3—C4 | 1.376 (3) |
N1—C4 | 1.476 (3) | C4—C5 | 1.375 (3) |
N2—C8 | 1.315 (3) | C5—C6 | 1.380 (3) |
N2—C9i | 1.327 (3) | C8—C9 | 1.370 (4) |
Symmetry code: (i) −x, −y+1, −z+1. |
Hydrogen-bond geometry (Å, º) for (I) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···N2 | 0.84 (3) | 1.85 (3) | 2.686 (3) | 175 (3) |
C3—H2···O3ii | 0.896 (19) | 2.55 (2) | 3.294 (4) | 140.9 (18) |
C5—H3···O2iii | 0.95 (2) | 2.45 (2) | 3.345 (3) | 158 (2) |
C8—H5···O4iv | 0.93 (3) | 2.48 (3) | 3.053 (4) | 120 (2) |
Symmetry codes: (ii) −x+1, −y+1, −z; (iii) −x+3/2, y−1/2, −z+1/2; (iv) −x+3/2, y+1/2, −z+1/2. |
Selected bond lengths (Å) for (II) topCl—C2 | 1.730 (3) | C1—C2 | 1.401 (3) |
O1—C7 | 1.308 (3) | C1—C6 | 1.396 (3) |
O2—C7 | 1.197 (3) | C1—C7 | 1.512 (3) |
O3—N1 | 1.218 (3) | C2—C3 | 1.387 (4) |
O4—N1 | 1.216 (3) | C3—C4 | 1.377 (4) |
N1—C5 | 1.481 (3) | C4—C5 | 1.370 (4) |
N2—C8 | 1.335 (3) | C5—C6 | 1.375 (3) |
N2—C9 | 1.327 (4) | C8—C9i | 1.376 (4) |
Symmetry code: (i) −x+1, −y+1, −z. |
Hydrogen-bond geometry (Å, º) for (II) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···N2 | 1.00 (3) | 1.71 (3) | 2.699 (3) | 173 (3) |
C3—H2···O2ii | 0.96 (2) | 2.64 (2) | 3.496 (4) | 149.3 (19) |
C4—H3···O3iii | 0.97 (2) | 2.53 (2) | 3.301 (4) | 136.8 (17) |
Symmetry codes: (ii) −x, y−1/2, −z+1/2; (iii) −x−1, −y, −z. |
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Several hydrogen-bonded complexes composed of 2-chloro-4-nitrobenzoic acid and amines were studied by Habeeb et al. using 35Cl NQR and IR techniques (Kalenik et al., 1989; Habeeb & Awad, 1995; Awad & Habeeb, 1996). They reported that the hydrogen bonds formed between the benzoic acid and the amines vary from an O—H···N to an O···H—N type with increasing proton affinities (PA) of the amines and that the critical (inversion) point at 50% proton transfer exists in the complex of 3,5-dimethylpyridine. However, there is not yet any crystallographic evidence supporting these findings. Moreover, the shapes of the proton donor and acceptor molecules may be important as the PA in determining the proton transfer. This prompted us to carry out studies on the structure of chloro- and nitro-substituted benzoic acid-amine complexes. In addition to the O—H···N/O···H—N hydrogen bond, other weak intermolecular interactions, such as C—H···O and C—H···Cl interactions, may be expected in these complexes, because the nitro group and the chlorine atom of these benzoic acids can act as a weak hydrogen bond acceptor (Robinson et al., 2000; Desiraju & Steiner, 1999). It is of relevance, therefore, in the context of crystal engineering and supramolecular architecture to investigate the role of the weak hydrogen-bond acceptors playing in the crystal packing of the title complexes. In the present study, we undertook pyrazine as an amine having a quite small PA value and prepared 2-chloro-4-nitrobenzoic acid-pyrazine and 2-chloro-5-nitrobenzoic acid-pyrazine complexes; their crystal structures were determined at room temperature. To our knowledge, this is the first crystallographic report of 2-chloro-4-nitrobenzoic acid-amine and 2-chloro-5-nitrobenzoic acid-amine systems; no structural data of compounds composed of 2-chloro-4-nitrobenzoic acid and 2-chloro-5-nitrobenzoic acid except 2-chloro-5-nitrobenzoic acid itself are recorded in Cambridge Structural Database (Version 5.20, October 2000). \sch
The pyrazine molecule in both 2-chloro-4-nitrobenzoic acid-pyrazine 2:1 complex, (I), and 2-chloro-5-nitrobenzoic acid-pyrazine 2:1 complex, (II), occupies a center of symmetry, and asymmetric units of (I) and (II) are composed of C7H4ClNO4.1/2C4H4N2. In both crystals the two components are held together by a short O—H···N hydrogen bond (Tables 2 and 4), forming the unit of 2C7H4ClNO4·C4H4N2 (Figs 1 and 2). No acid-base interaction involving a proton transfer is observed as expected from the small PA value of pyrazine. The O···N distances are long compared with the shortest expected O···N distance of ca 2.45 Å (Jerzykiewicz et al., 1998), which may be realised in the vicinity of the critical point.
In (I), the dihedral angle between the nitro group and the benzene ring is 18.97 (13)° and that between the carboxyl group and the benzene ring is 32.77 (12)°. The dihedral angle between the planes of the pyrazine ring and the benzene ring by 19.56 (12)°. On the other hand, in (II), all the atoms locate almost on a plane; the benzene ring makes small angles of 3.19 (13), 9.17 (13) and 5.56 (13)° with the nitro group, the carboxyl group and the pyrazine ring, respectively. To compare these geometries with those of the isolated molecules in gas phase, we carried out ab initio MO calculations at the HF/6–31G** level of theory by using the computer program Gaussian 98 (Frisch et al., 1998). The optimized geometries were confirmed to correspond to a potential energy minimum from vibrational analysis. The calculated dihedral angles of the nitro group and the carboxyl group made by the benzene ring are 0.3° and 30.1°, respectively, for 2-chloro-4-nitrobenzoic acid and 0.5° and 20.0° for 2-chloro-5-nitrobenzoic acid. We also obtained flat structures for both benzoic acids, which were found not as a stable form but at a saddle point of first order. The angles of the nitro group in (I) and the carboxyl group in (II) are much larger and smaller, respectively, compared with the calculated values, the former and the latter of which may be interpreted as arising from intermolecular C—H···O interactions involving the nitro groups and aromatic π-π stacking interactions, respectively, as mentioned below.
In (I), an intermolecular C—H···O interaction (Table 2) is observed between the benzene ring and the nitro group, forming a centrosymmetric ring with graph-set descriptor R22(10) (Bernstein et al., 1995). The interaction connects the units of 2[C7H4ClNO4]·C4H4N2 to build a zigzag chain running along the [101] direction. The chains are linked by a C—H···O hydrogen bond formed between the benzene ring and the carboxyl group and a C—H···O interaction between the pyrazine and the nitro group (Table 2), generating a three-dimensional hydrogen-bond network (Fig. 3).
In (II), a C—H···O interaction (Table 4) between the benzoic acids related by an inversion center forms the R22(10) ring with a similar geometry to that in (I) and links the units of 2[C7H4ClNO4]·C4H4N2, resulting in the formation of ribbons running parallel to the [210] and [210] directions. An additional weak C—H···O interaction (Table 4) and a Cl···Cli contact at 3.7378 (12) Å [symmetry code: (i) -x, 1/2 + y, 1/2 - z] is found between the ribbons running different directions. The ribbons are stacked along the b axis, forming two kinds of layer (Fig. 4), in which the benzoic acids related by an inversion center are stacked through the π-π interactions with the interplanar spacing of 3.397 (5) Å and the centroid offset of 2.57 Å.