Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104003063/fr1460sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270104003063/fr1460Isup2.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270104003063/fr1460IIsup3.hkl |
CCDC references: 237939; 237940
2,4-Dimethoxybenzoic acid (C9H10O4) and 2,5-dimethoxybenzoic acid (C9H10O4) were obtained from Aldrich and used without purification. Each sample was recrystallized from methanol.
The positions of the H atoms on the carboxylic groups were found from difference maps and refined independently. The positions of all other H atoms were determined geometrically and refined with a riding model. The displacement parameters for the H atoms were assigned values of 1.2Uiso (1.5Uiso for methyl groups) of the carrier atom. Bonds between H atoms and aromatic C atoms were set to 0.95 Å; bonds between H atoms and methyl C atoms were set to 0.98 Å.
For both compounds, data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1997); software used to prepare material for publication: SHELXTL.
C9H10O4 | Z = 2 |
Mr = 182.17 | F(000) = 192 |
Triclinic, P1 | Dx = 1.472 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 6.7602 (13) Å | Cell parameters from 1306 reflections |
b = 7.7124 (15) Å | θ = 2.6–26.0° |
c = 8.0237 (15) Å | µ = 0.12 mm−1 |
α = 94.995 (4)° | T = 100 K |
β = 95.894 (4)° | Block, colorless |
γ = 96.759 (4)° | 0.22 × 0.17 × 0.04 mm |
V = 411.14 (14) Å3 |
Bruker SMART APEX diffractometer | 1563 independent reflections |
Radiation source: fine-focus sealed tube | 1298 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.012 |
ω scan | θmax = 26.0°, θmin = 2.6° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2000) | h = −7→8 |
Tmin = 0.975, Tmax = 0.995 | k = −9→9 |
2584 measured reflections | l = −9→7 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.047 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.136 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | w = 1/[σ2(Fo2) + (0.1P)2] where P = (Fo2 + 2Fc2)/3 |
1563 reflections | (Δ/σ)max = 0.001 |
121 parameters | Δρmax = 0.37 e Å−3 |
0 restraints | Δρmin = −0.43 e Å−3 |
C9H10O4 | γ = 96.759 (4)° |
Mr = 182.17 | V = 411.14 (14) Å3 |
Triclinic, P1 | Z = 2 |
a = 6.7602 (13) Å | Mo Kα radiation |
b = 7.7124 (15) Å | µ = 0.12 mm−1 |
c = 8.0237 (15) Å | T = 100 K |
α = 94.995 (4)° | 0.22 × 0.17 × 0.04 mm |
β = 95.894 (4)° |
Bruker SMART APEX diffractometer | 1563 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2000) | 1298 reflections with I > 2σ(I) |
Tmin = 0.975, Tmax = 0.995 | Rint = 0.012 |
2584 measured reflections |
R[F2 > 2σ(F2)] = 0.047 | 0 restraints |
wR(F2) = 0.136 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.37 e Å−3 |
1563 reflections | Δρmin = −0.43 e Å−3 |
121 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
O1 | −0.32568 (15) | 0.66932 (14) | 0.49547 (14) | 0.0201 (3) | |
O2 | −0.31184 (16) | 0.44318 (14) | 0.65036 (15) | 0.0220 (3) | |
H2 | −0.440 (3) | 0.413 (2) | 0.599 (3) | 0.026* | |
O3 | 0.03560 (16) | 0.40777 (14) | 0.81414 (15) | 0.0197 (3) | |
O4 | 0.56153 (16) | 0.87315 (14) | 0.83949 (15) | 0.0207 (3) | |
C1 | −0.0226 (2) | 0.65497 (19) | 0.66673 (19) | 0.0167 (4) | |
C2 | 0.1060 (2) | 0.5678 (2) | 0.7711 (2) | 0.0163 (4) | |
C3 | 0.3004 (2) | 0.6476 (2) | 0.8251 (2) | 0.0174 (4) | |
H3 | 0.3875 | 0.5895 | 0.8953 | 0.021* | |
C4 | 0.3688 (2) | 0.8112 (2) | 0.7776 (2) | 0.0181 (4) | |
C5 | 0.2451 (2) | 0.8997 (2) | 0.6758 (2) | 0.0190 (4) | |
H5 | 0.2908 | 1.0121 | 0.6442 | 0.023* | |
C6 | 0.0522 (2) | 0.8185 (2) | 0.6218 (2) | 0.0184 (4) | |
H6 | −0.0332 | 0.8772 | 0.5507 | 0.022* | |
C7 | −0.2321 (2) | 0.58778 (19) | 0.5979 (2) | 0.0159 (4) | |
C8 | 0.1728 (2) | 0.3211 (2) | 0.9146 (2) | 0.0216 (4) | |
H8A | 0.1061 | 0.2069 | 0.9366 | 0.032* | |
H8B | 0.2171 | 0.3931 | 1.0217 | 0.032* | |
H8C | 0.2891 | 0.3039 | 0.8545 | 0.032* | |
C9 | 0.6450 (2) | 1.0374 (2) | 0.7891 (2) | 0.0232 (4) | |
H9A | 0.7859 | 1.0639 | 0.8367 | 0.035* | |
H9B | 0.5701 | 1.1306 | 0.8303 | 0.035* | |
H9C | 0.6360 | 1.0301 | 0.6660 | 0.035* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0118 (6) | 0.0220 (6) | 0.0238 (7) | −0.0025 (4) | −0.0067 (5) | 0.0046 (5) |
O2 | 0.0113 (6) | 0.0226 (6) | 0.0289 (7) | −0.0062 (4) | −0.0072 (5) | 0.0078 (5) |
O3 | 0.0127 (6) | 0.0180 (5) | 0.0262 (7) | −0.0032 (4) | −0.0067 (5) | 0.0073 (5) |
O4 | 0.0098 (6) | 0.0218 (6) | 0.0269 (7) | −0.0061 (4) | −0.0072 (5) | 0.0036 (5) |
C1 | 0.0103 (8) | 0.0202 (8) | 0.0174 (9) | −0.0018 (6) | −0.0031 (6) | 0.0004 (6) |
C2 | 0.0124 (7) | 0.0173 (8) | 0.0174 (9) | −0.0026 (6) | −0.0010 (6) | 0.0013 (6) |
C3 | 0.0112 (8) | 0.0205 (8) | 0.0188 (9) | 0.0002 (6) | −0.0054 (6) | 0.0029 (6) |
C4 | 0.0106 (8) | 0.0221 (8) | 0.0189 (9) | −0.0028 (6) | −0.0026 (6) | −0.0022 (6) |
C5 | 0.0138 (8) | 0.0174 (7) | 0.0235 (9) | −0.0042 (6) | −0.0038 (6) | 0.0045 (6) |
C6 | 0.0134 (8) | 0.0200 (8) | 0.0202 (9) | −0.0006 (6) | −0.0045 (6) | 0.0037 (6) |
C7 | 0.0117 (8) | 0.0178 (7) | 0.0166 (8) | 0.0002 (6) | −0.0030 (6) | 0.0003 (6) |
C8 | 0.0151 (8) | 0.0209 (8) | 0.0272 (9) | −0.0013 (6) | −0.0055 (7) | 0.0073 (6) |
C9 | 0.0128 (8) | 0.0235 (8) | 0.0298 (10) | −0.0073 (6) | −0.0037 (7) | 0.0033 (7) |
O1—C7 | 1.2441 (18) | C3—H3 | 0.9500 |
O2—C7 | 1.3031 (19) | C4—C5 | 1.387 (2) |
O2—H2 | 0.91 (2) | C5—C6 | 1.387 (2) |
O3—C2 | 1.3560 (18) | C5—H5 | 0.9500 |
O3—C8 | 1.429 (2) | C6—H6 | 0.9500 |
O4—C4 | 1.3607 (18) | C8—H8A | 0.9800 |
O4—C9 | 1.4332 (19) | C8—H8B | 0.9800 |
C1—C6 | 1.394 (2) | C8—H8C | 0.9800 |
C1—C2 | 1.412 (2) | C9—H9A | 0.9800 |
C1—C7 | 1.482 (2) | C9—H9B | 0.9800 |
C2—C3 | 1.393 (2) | C9—H9C | 0.9800 |
C3—C4 | 1.390 (2) | ||
C7—O2—H2 | 109.7 (12) | C5—C6—C1 | 123.24 (14) |
C2—O3—C8 | 116.76 (12) | C5—C6—H6 | 118.4 |
C4—O4—C9 | 117.53 (12) | C1—C6—H6 | 118.4 |
C6—C1—C2 | 117.98 (14) | O1—C7—O2 | 122.48 (13) |
C6—C1—C7 | 116.10 (14) | O1—C7—C1 | 120.21 (14) |
C2—C1—C7 | 125.91 (14) | O2—C7—C1 | 117.31 (13) |
O3—C2—C3 | 122.24 (14) | O3—C8—H8A | 109.5 |
O3—C2—C1 | 118.51 (13) | O3—C8—H8B | 109.5 |
C3—C2—C1 | 119.25 (13) | H8A—C8—H8B | 109.5 |
C4—C3—C2 | 120.89 (14) | O3—C8—H8C | 109.5 |
C4—C3—H3 | 119.6 | H8A—C8—H8C | 109.5 |
C2—C3—H3 | 119.6 | H8B—C8—H8C | 109.5 |
O4—C4—C5 | 124.54 (14) | O4—C9—H9A | 109.5 |
O4—C4—C3 | 114.54 (13) | O4—C9—H9B | 109.5 |
C5—C4—C3 | 120.92 (14) | H9A—C9—H9B | 109.5 |
C4—C5—C6 | 117.71 (14) | O4—C9—H9C | 109.5 |
C4—C5—H5 | 121.1 | H9A—C9—H9C | 109.5 |
C6—C5—H5 | 121.1 | H9B—C9—H9C | 109.5 |
C8—O3—C2—C3 | −1.7 (2) | C2—C3—C4—C5 | 0.3 (3) |
C8—O3—C2—C1 | 177.73 (14) | O4—C4—C5—C6 | 179.60 (15) |
C6—C1—C2—O3 | −179.31 (14) | C3—C4—C5—C6 | −0.7 (2) |
C7—C1—C2—O3 | 0.1 (3) | C4—C5—C6—C1 | 0.9 (3) |
C6—C1—C2—C3 | 0.2 (2) | C2—C1—C6—C5 | −0.6 (3) |
C7—C1—C2—C3 | 179.57 (14) | C7—C1—C6—C5 | 179.91 (15) |
O3—C2—C3—C4 | 179.45 (14) | C6—C1—C7—O1 | 5.6 (2) |
C1—C2—C3—C4 | 0.0 (2) | C2—C1—C7—O1 | −173.80 (14) |
C9—O4—C4—C5 | −3.2 (2) | C6—C1—C7—O2 | −173.78 (13) |
C9—O4—C4—C3 | 177.13 (13) | C2—C1—C7—O2 | 6.8 (2) |
C2—C3—C4—O4 | −179.99 (13) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2···O1i | 0.91 (2) | 1.71 (2) | 2.6192 (15) | 172.7 (18) |
Symmetry code: (i) −x−1, −y+1, −z+1. |
C9H10O4 | F(000) = 384 |
Mr = 182.17 | Dx = 1.444 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 2576 reflections |
a = 10.0810 (17) Å | θ = 2.6–26.0° |
b = 12.534 (2) Å | µ = 0.11 mm−1 |
c = 6.6408 (11) Å | T = 100 K |
β = 92.729 (4)° | Block, colorless |
V = 838.1 (2) Å3 | 0.33 × 0.17 × 0.06 mm |
Z = 4 |
Bruker SMART APEX diffractometer | 1633 independent reflections |
Radiation source: fine-focus sealed tube | 1421 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.023 |
ω scan | θmax = 26.0°, θmin = 2.0° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2000) | h = −12→11 |
Tmin = 0.963, Tmax = 0.993 | k = −15→15 |
5021 measured reflections | l = −8→8 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.060 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.168 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.01 | w = 1/[σ2(Fo2) + (0.086P)2 + 1.5P] where P = (Fo2 + 2Fc2)/3 |
1633 reflections | (Δ/σ)max = 0.007 |
122 parameters | Δρmax = 0.51 e Å−3 |
0 restraints | Δρmin = −0.34 e Å−3 |
C9H10O4 | V = 838.1 (2) Å3 |
Mr = 182.17 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 10.0810 (17) Å | µ = 0.11 mm−1 |
b = 12.534 (2) Å | T = 100 K |
c = 6.6408 (11) Å | 0.33 × 0.17 × 0.06 mm |
β = 92.729 (4)° |
Bruker SMART APEX diffractometer | 1633 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2000) | 1421 reflections with I > 2σ(I) |
Tmin = 0.963, Tmax = 0.993 | Rint = 0.023 |
5021 measured reflections |
R[F2 > 2σ(F2)] = 0.060 | 0 restraints |
wR(F2) = 0.168 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.01 | Δρmax = 0.51 e Å−3 |
1633 reflections | Δρmin = −0.34 e Å−3 |
122 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.71941 (17) | 0.05660 (13) | 0.2269 (3) | 0.0212 (4) | |
O2 | 0.57149 (18) | 0.18440 (15) | 0.1831 (3) | 0.0277 (5) | |
H2 | 0.574 (3) | 0.255 (3) | 0.176 (5) | 0.033* | |
O3 | 0.64950 (17) | 0.37763 (13) | 0.1990 (3) | 0.0209 (5) | |
O4 | 1.16150 (16) | 0.22282 (13) | 0.3016 (3) | 0.0209 (5) | |
C1 | 0.8032 (2) | 0.23472 (18) | 0.2342 (3) | 0.0154 (5) | |
C2 | 0.7797 (2) | 0.34550 (19) | 0.2273 (3) | 0.0164 (5) | |
C3 | 0.8850 (3) | 0.41606 (18) | 0.2465 (4) | 0.0188 (5) | |
H3 | 0.8688 | 0.4907 | 0.2426 | 0.023* | |
C4 | 1.0148 (2) | 0.37824 (19) | 0.2714 (4) | 0.0180 (5) | |
H4 | 1.0869 | 0.4269 | 0.2837 | 0.022* | |
C5 | 1.0382 (2) | 0.26884 (19) | 0.2780 (3) | 0.0165 (5) | |
C6 | 0.9329 (2) | 0.19846 (18) | 0.2591 (3) | 0.0162 (5) | |
H6 | 0.9496 | 0.1239 | 0.2632 | 0.019* | |
C7 | 0.6968 (2) | 0.15122 (19) | 0.2155 (3) | 0.0177 (5) | |
C8 | 0.6182 (3) | 0.48894 (19) | 0.2224 (4) | 0.0228 (6) | |
H8A | 0.5217 | 0.4985 | 0.2129 | 0.034* | |
H8B | 0.6585 | 0.5302 | 0.1159 | 0.034* | |
H8C | 0.6533 | 0.5138 | 0.3544 | 0.034* | |
C9 | 1.2719 (2) | 0.2943 (2) | 0.3229 (4) | 0.0236 (6) | |
H9A | 1.2743 | 0.3398 | 0.2031 | 0.035* | |
H9B | 1.3544 | 0.2531 | 0.3376 | 0.035* | |
H9C | 1.2625 | 0.3389 | 0.4425 | 0.035* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0196 (9) | 0.0117 (9) | 0.0324 (10) | −0.0018 (7) | 0.0034 (7) | −0.0007 (7) |
O2 | 0.0160 (9) | 0.0129 (9) | 0.0540 (13) | −0.0013 (7) | 0.0001 (8) | 0.0020 (8) |
O3 | 0.0161 (9) | 0.0106 (8) | 0.0359 (10) | 0.0018 (6) | 0.0002 (7) | −0.0015 (7) |
O4 | 0.0138 (9) | 0.0131 (9) | 0.0359 (10) | −0.0004 (7) | 0.0015 (7) | −0.0006 (7) |
C1 | 0.0187 (12) | 0.0121 (11) | 0.0158 (11) | −0.0022 (9) | 0.0025 (9) | −0.0009 (8) |
C2 | 0.0165 (12) | 0.0155 (12) | 0.0171 (11) | 0.0026 (9) | 0.0015 (9) | −0.0006 (8) |
C3 | 0.0239 (13) | 0.0085 (10) | 0.0241 (12) | 0.0001 (9) | 0.0022 (10) | −0.0002 (9) |
C4 | 0.0173 (12) | 0.0127 (11) | 0.0238 (12) | −0.0040 (9) | 0.0009 (9) | −0.0010 (9) |
C5 | 0.0170 (12) | 0.0148 (12) | 0.0178 (12) | 0.0008 (9) | 0.0024 (9) | −0.0003 (8) |
C6 | 0.0206 (12) | 0.0105 (11) | 0.0177 (11) | 0.0004 (9) | 0.0037 (9) | 0.0009 (8) |
C7 | 0.0182 (12) | 0.0155 (12) | 0.0195 (12) | −0.0006 (9) | 0.0026 (9) | −0.0009 (9) |
C8 | 0.0227 (13) | 0.0123 (12) | 0.0331 (14) | 0.0063 (10) | −0.0014 (10) | −0.0019 (10) |
C9 | 0.0159 (12) | 0.0205 (13) | 0.0346 (15) | −0.0025 (10) | 0.0020 (10) | −0.0008 (10) |
O1—C7 | 1.209 (3) | C3—H3 | 0.9500 |
O2—C7 | 1.338 (3) | C4—C5 | 1.392 (3) |
O2—H2 | 0.88 (4) | C4—H4 | 0.9500 |
O3—C2 | 1.377 (3) | C5—C6 | 1.381 (3) |
O3—C8 | 1.440 (3) | C6—H6 | 0.9500 |
O4—C5 | 1.372 (3) | C8—H8A | 0.9800 |
O4—C9 | 1.430 (3) | C8—H8B | 0.9800 |
C1—C6 | 1.386 (3) | C8—H8C | 0.9800 |
C1—C2 | 1.409 (3) | C9—H9A | 0.9800 |
C1—C7 | 1.499 (3) | C9—H9B | 0.9800 |
C2—C3 | 1.383 (3) | C9—H9C | 0.9800 |
C3—C4 | 1.394 (4) | ||
C7—O2—H2 | 107 (2) | C5—C6—C1 | 121.2 (2) |
C2—O3—C8 | 118.72 (19) | C5—C6—H6 | 119.4 |
C5—O4—C9 | 116.37 (18) | C1—C6—H6 | 119.4 |
C6—C1—C2 | 118.9 (2) | O1—C7—O2 | 119.2 (2) |
C6—C1—C7 | 116.6 (2) | O1—C7—C1 | 123.2 (2) |
C2—C1—C7 | 124.5 (2) | O2—C7—C1 | 117.6 (2) |
O3—C2—C3 | 123.2 (2) | O3—C8—H8A | 109.5 |
O3—C2—C1 | 116.8 (2) | O3—C8—H8B | 109.5 |
C3—C2—C1 | 120.0 (2) | H8A—C8—H8B | 109.5 |
C2—C3—C4 | 120.4 (2) | O3—C8—H8C | 109.5 |
C2—C3—H3 | 119.8 | H8A—C8—H8C | 109.5 |
C4—C3—H3 | 119.8 | H8B—C8—H8C | 109.5 |
C5—C4—C3 | 119.7 (2) | O4—C9—H9A | 109.5 |
C5—C4—H4 | 120.1 | O4—C9—H9B | 109.5 |
C3—C4—H4 | 120.1 | H9A—C9—H9B | 109.5 |
O4—C5—C6 | 115.5 (2) | O4—C9—H9C | 109.5 |
O4—C5—C4 | 124.7 (2) | H9A—C9—H9C | 109.5 |
C6—C5—C4 | 119.9 (2) | H9B—C9—H9C | 109.5 |
C8—O3—C2—C3 | −10.3 (3) | C3—C4—C5—O4 | 179.9 (2) |
C8—O3—C2—C1 | 170.4 (2) | C3—C4—C5—C6 | 0.3 (4) |
C6—C1—C2—O3 | 178.9 (2) | O4—C5—C6—C1 | −179.9 (2) |
C7—C1—C2—O3 | −0.8 (3) | C4—C5—C6—C1 | −0.3 (3) |
C6—C1—C2—C3 | −0.4 (3) | C2—C1—C6—C5 | 0.3 (3) |
C7—C1—C2—C3 | 179.9 (2) | C7—C1—C6—C5 | −179.9 (2) |
O3—C2—C3—C4 | −178.9 (2) | C6—C1—C7—O1 | 2.2 (3) |
C1—C2—C3—C4 | 0.4 (4) | C2—C1—C7—O1 | −178.1 (2) |
C2—C3—C4—C5 | −0.3 (4) | C6—C1—C7—O2 | −177.3 (2) |
C9—O4—C5—C6 | −179.6 (2) | C2—C1—C7—O2 | 2.4 (3) |
C9—O4—C5—C4 | 0.8 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2···O3 | 0.88 (4) | 1.72 (4) | 2.547 (2) | 154 (3) |
Experimental details
(I) | (II) | |
Crystal data | ||
Chemical formula | C9H10O4 | C9H10O4 |
Mr | 182.17 | 182.17 |
Crystal system, space group | Triclinic, P1 | Monoclinic, P21/c |
Temperature (K) | 100 | 100 |
a, b, c (Å) | 6.7602 (13), 7.7124 (15), 8.0237 (15) | 10.0810 (17), 12.534 (2), 6.6408 (11) |
α, β, γ (°) | 94.995 (4), 95.894 (4), 96.759 (4) | 90, 92.729 (4), 90 |
V (Å3) | 411.14 (14) | 838.1 (2) |
Z | 2 | 4 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.12 | 0.11 |
Crystal size (mm) | 0.22 × 0.17 × 0.04 | 0.33 × 0.17 × 0.06 |
Data collection | ||
Diffractometer | Bruker SMART APEX diffractometer | Bruker SMART APEX diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2000) | Multi-scan (SADABS; Sheldrick, 2000) |
Tmin, Tmax | 0.975, 0.995 | 0.963, 0.993 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2584, 1563, 1298 | 5021, 1633, 1421 |
Rint | 0.012 | 0.023 |
(sin θ/λ)max (Å−1) | 0.617 | 0.617 |
Refinement | ||
R[F2 > 2σ(F2)], wR(F2), S | 0.047, 0.136, 1.04 | 0.060, 0.168, 1.01 |
No. of reflections | 1563 | 1633 |
No. of parameters | 121 | 122 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.37, −0.43 | 0.51, −0.34 |
Computer programs: SMART (Bruker, 1998), SMART, SAINT (Bruker, 1998), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), SHELXTL (Sheldrick, 1997), SHELXTL.
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2···O1i | 0.91 (2) | 1.71 (2) | 2.6192 (15) | 172.7 (18) |
Symmetry code: (i) −x−1, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H2···O3 | 0.88 (4) | 1.72 (4) | 2.547 (2) | 154 (3) |
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The crystal structures of only four of the six isomers of dimethoxybenzoic acid (DMBA) have been determined previously. These four isomers exhibit considerable conformational differences. For example, the plane defined by the carboxylic acid group lies nearly parallel to the aromatic ring plane in 3,4-DMBA (3.4°; Pinkus et al., 2002) and 3,5-DMBA (1.4°; Lynch et al., 1994), but is 36.5 and 56.2° out of the plane in 2,3-DMBA (Swaminathan et al., 1977; Bryan & White, 1982a) and 2,6-DMBA (Swaminathan et al., 1976; Bryan & White, 1982b). For the title compounds, this angle is 6.3 (2) (2,4-DMBA) and 2.3 (3)° (2,5-DMBA).
The 2,4-dimethoxybenzoic acid (DMBA) isomer (Fig. 1) exhibits the relatively common intermolecular hydrogen-bond arrangment between the carboxylic acid of two molecules centered about an inversion center. This overall hydrogen-bonding arrangement is also found in 2,3-DMBA (Swaminathan et al., 1977; Bryan & White, 1982a), 3,4-DMBA (Pinkus et al., 2002) and 3,5-DMBA (Lynch et al., 1994), as welll as in 2-methoxybenzoic acid (Parvez, 1987) and 4-methoxybenzoic acid (Etter et al., 1988), the two monomethoxybenzoic acids with determined crystal structures.
The hydrogen-bonding arrangement of 2,5-DMBA (Fig. 2) is unusual in that, unlike most of the DMBA isomers, the carboxylic acid group does not hydrogen bond with a neighboring molecule's carboxylic acid group but instead forms an intramolecular hydrogen bond with the methoxy O atom that is bonded to atom C2. The donor–acceptor distance of this intramolecular hydrogen bond is 2.547 (2) Å and the angle from the donor to the H atom to the acceptor is 154 (3)°.