In the crystalline state, the title molecule, C
18H
16O
4, exists in the enolized form and displays a strong intramolecular hydrogen bond. The molecular structure, as well as theoretical calculations, support the hypothesis that the conjugation in the molecule is a determining factor for the position of the enol H atom. The packing of the molecules is dominated by interactions between 3-methoxy-4-hydroxyphenyl- and enol groups, thus forming planar molecular chains. These interactions include normal O—H
O bonds, as well as weak C—H
O interactions and van der Waals forces.
Supporting information
CCDC reference: 239305
Key indicators
- Single-crystal X-ray study
- T = 150 K
- Mean (C-C) = 0.003 Å
- R factor = 0.032
- wR factor = 0.090
- Data-to-parameter ratio = 7.6
checkCIF/PLATON results
No syntax errors found
Alert level A
PLAT772_ALERT_2_A Suspect O-H Bond in CIF: O1 -H20 .. 1.47 Ang.
Alert level B
PLAT222_ALERT_3_B Large Non-Solvent H Ueq(max)/Ueq(min) ... 4.39 Ratio
PLAT355_ALERT_3_B Long O-H Bond (0.82A) O2 - H20 ... 1.08 Ang.
Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical . ?
PLAT068_ALERT_1_C Reported F000 Differs from Calcd (or Missing)... ?
PLAT089_ALERT_3_C Poor Data / Parameter Ratio (Zmax .LT. 18) ..... 7.57
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given ....... ?
PLAT480_ALERT_4_C Long H...A H-Bond Reported H8 .. O4 .. 2.71 Ang.
Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
correct. If it is not, please give the correct count in the
_publ_section_exptl_refinement section of the submitted CIF.
From the CIF: _diffrn_reflns_theta_max 28.27
From the CIF: _reflns_number_total 1992
Count of symmetry unique reflns 1995
Completeness (_total/calc) 99.85%
TEST3: Check Friedels for noncentro structure
Estimate of Friedel pairs measured 0
Fraction of Friedel pairs measured 0.000
Are heavy atom types Z>Si present no
1 ALERT level A = In general: serious problem
2 ALERT level B = Potentially serious problem
5 ALERT level C = Check and explain
1 ALERT level G = General alerts; check
2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
1 ALERT type 2 Indicator that the structure model may be wrong or deficient
3 ALERT type 3 Indicator that the structure quality may be low
3 ALERT type 4 Improvement, methodology, query or suggestion
Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXL97; software used to prepare material for publication: SHELXL97.
Crystal data top
C18H16O4 | Dx = 1.353 Mg m−3 |
Mr = 296.31 | Melting point: 427 K |
Orthorhombic, Pna21 | Mo Kα radiation, λ = 0.71073 Å |
a = 21.177 (4) Å | Cell parameters from 15654 reflections |
b = 12.291 (3) Å | θ = 2.0–28.4° |
c = 5.627 (1) Å | µ = 0.10 mm−1 |
V = 1464.6 (5) Å3 | T = 150 K |
Z = 4 | Needle, yellow |
F(000) = 632 | 0.5 × 0.3 × 0.1 mm |
Data collection top
Bruker SMART diffractometer | 1992 independent reflections |
Radiation source: fine-focus sealed tube | 1821 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.031 |
Detector resolution: 8 pixels mm-1 | θmax = 28.3°, θmin = 1.9° |
ω scans | h = −27→28 |
Absorption correction: empirical (using intensity measurements) (SADABS (Sheldrick, 1997) | k = −16→16 |
Tmin = 0.954, Tmax = 0.991 | l = −7→7 |
24695 measured reflections | |
Refinement top
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)] = 0.032 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.090 | All H-atom parameters refined |
S = 1.08 | w = 1/[σ2(Fo2) + (0.0642P)2 + 0.1885P] where P = (Fo2 + 2Fc2)/3 |
1992 reflections | (Δ/σ)max = 0.005 |
263 parameters | Δρmax = 0.23 e Å−3 |
1 restraint | Δρmin = −0.18 e Å−3 |
Special details top
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) top | x | y | z | Uiso*/Ueq | |
O1 | 0.09319 (6) | 0.78303 (13) | 0.5748 (3) | 0.0381 (4) | |
O2 | 0.20047 (6) | 0.82217 (13) | 0.4163 (3) | 0.0402 (4) | |
H20 | 0.1609 (18) | 0.799 (3) | 0.526 (9) | 0.101 (12)* | |
O3 | 0.31631 (5) | 1.14749 (10) | −0.6401 (3) | 0.0285 (3) | |
O4 | 0.44141 (6) | 1.13069 (12) | −0.5688 (3) | 0.0311 (3) | |
H40 | 0.4215 (12) | 1.171 (2) | −0.665 (6) | 0.048 (7)* | |
C1 | 0.06883 (8) | 0.82360 (14) | 0.3879 (4) | 0.0266 (4) | |
C2 | 0.10774 (8) | 0.86665 (14) | 0.2058 (4) | 0.0272 (4) | |
H2 | 0.0895 (10) | 0.8967 (17) | 0.061 (5) | 0.028 (5)* | |
C3 | 0.17316 (8) | 0.86454 (13) | 0.2273 (3) | 0.0263 (4) | |
C4 | 0.21351 (8) | 0.91056 (14) | 0.0448 (4) | 0.0264 (4) | |
H4 | 0.1930 (10) | 0.9341 (17) | −0.095 (5) | 0.027 (5)* | |
C5 | 0.27682 (8) | 0.91799 (13) | 0.0649 (4) | 0.0259 (4) | |
H5 | 0.2976 (10) | 0.8906 (16) | 0.200 (4) | 0.023 (5)* | |
C6 | 0.31909 (7) | 0.97097 (12) | −0.1050 (3) | 0.0242 (4) | |
C7 | 0.38467 (8) | 0.96675 (14) | −0.0717 (4) | 0.0274 (4) | |
H7 | 0.4009 (10) | 0.9269 (17) | 0.063 (5) | 0.027 (5)* | |
C8 | 0.42517 (8) | 1.01927 (14) | −0.2299 (4) | 0.0284 (4) | |
H8 | 0.4697 (9) | 1.0150 (16) | −0.204 (4) | 0.026 (5)* | |
C9 | 0.40136 (8) | 1.07864 (14) | −0.4189 (4) | 0.0255 (4) | |
C10 | 0.33494 (7) | 1.08475 (13) | −0.4521 (3) | 0.0242 (3) | |
C11 | 0.29525 (8) | 1.03015 (13) | −0.2992 (4) | 0.0248 (3) | |
H11 | 0.2497 (10) | 1.0362 (16) | −0.330 (4) | 0.023 (5)* | |
C13 | −0.00169 (8) | 0.82550 (14) | 0.3684 (4) | 0.0259 (4) | |
C14 | −0.03296 (10) | 0.88654 (19) | 0.1969 (4) | 0.0392 (5) | |
C15 | −0.09861 (10) | 0.8870 (2) | 0.1863 (5) | 0.0432 (5) | |
H15 | −0.1212 (14) | 0.932 (2) | 0.058 (7) | 0.067 (9)* | |
C16 | −0.13326 (8) | 0.82633 (17) | 0.3459 (4) | 0.0333 (4) | |
H16 | −0.1791 (11) | 0.8266 (17) | 0.338 (5) | 0.036 (6)* | |
C17 | −0.10311 (9) | 0.7653 (2) | 0.5158 (5) | 0.0453 (6) | |
H17 | −0.1293 (14) | 0.726 (2) | 0.629 (6) | 0.063 (9)* | |
C18 | −0.03730 (9) | 0.7653 (2) | 0.5291 (5) | 0.0428 (6) | |
H18 | −0.0155 (13) | 0.718 (2) | 0.647 (6) | 0.058 (8)* | |
C12 | 0.24963 (8) | 1.16288 (15) | −0.6697 (4) | 0.0277 (4) | |
H122 | 0.2449 (11) | 1.2143 (19) | −0.799 (5) | 0.035 (6)* | |
H123 | 0.2293 (10) | 1.0933 (17) | −0.705 (5) | 0.028 (5)* | |
H121 | 0.2349 (10) | 1.2006 (18) | −0.525 (5) | 0.029 (6)* | |
H14 | −0.0099 (13) | 0.934 (2) | 0.090 (7) | 0.062 (8)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0248 (6) | 0.0563 (9) | 0.0334 (8) | −0.0056 (6) | −0.0025 (6) | 0.0162 (7) |
O2 | 0.0249 (6) | 0.0558 (9) | 0.0400 (9) | −0.0079 (6) | −0.0030 (6) | 0.0180 (8) |
O3 | 0.0180 (5) | 0.0392 (6) | 0.0284 (7) | 0.0016 (5) | 0.0007 (5) | 0.0033 (6) |
O4 | 0.0188 (5) | 0.0408 (7) | 0.0337 (7) | 0.0016 (5) | 0.0039 (5) | 0.0070 (6) |
C1 | 0.0241 (8) | 0.0271 (8) | 0.0287 (10) | −0.0017 (6) | −0.0004 (8) | 0.0015 (7) |
C2 | 0.0260 (8) | 0.0283 (8) | 0.0272 (9) | −0.0014 (7) | 0.0002 (7) | 0.0019 (8) |
C3 | 0.0275 (8) | 0.0228 (7) | 0.0284 (9) | −0.0029 (6) | 0.0017 (7) | −0.0002 (7) |
C4 | 0.0261 (8) | 0.0236 (7) | 0.0295 (10) | −0.0014 (6) | 0.0033 (8) | −0.0009 (7) |
C5 | 0.0287 (8) | 0.0216 (7) | 0.0274 (9) | 0.0002 (6) | 0.0036 (8) | −0.0008 (7) |
C6 | 0.0225 (7) | 0.0210 (7) | 0.0292 (9) | −0.0013 (6) | 0.0036 (7) | −0.0043 (7) |
C7 | 0.0261 (8) | 0.0269 (8) | 0.0293 (9) | 0.0012 (6) | −0.0011 (8) | −0.0002 (8) |
C8 | 0.0188 (7) | 0.0317 (8) | 0.0347 (10) | 0.0018 (6) | −0.0016 (7) | −0.0009 (8) |
C9 | 0.0206 (7) | 0.0273 (8) | 0.0286 (9) | 0.0010 (6) | 0.0044 (7) | −0.0039 (7) |
C10 | 0.0202 (7) | 0.0267 (8) | 0.0256 (8) | 0.0017 (6) | 0.0008 (7) | −0.0052 (7) |
C11 | 0.0197 (7) | 0.0249 (7) | 0.0298 (9) | 0.0014 (6) | 0.0019 (7) | −0.0045 (7) |
C13 | 0.0239 (7) | 0.0268 (7) | 0.0271 (9) | 0.0000 (6) | 0.0018 (7) | −0.0001 (7) |
C14 | 0.0291 (9) | 0.0528 (12) | 0.0356 (11) | −0.0027 (8) | 0.0016 (9) | 0.0174 (10) |
C15 | 0.0303 (9) | 0.0610 (13) | 0.0383 (11) | 0.0052 (9) | −0.0028 (9) | 0.0206 (11) |
C16 | 0.0225 (8) | 0.0422 (9) | 0.0350 (10) | 0.0033 (7) | 0.0005 (8) | 0.0044 (9) |
C17 | 0.0258 (9) | 0.0626 (14) | 0.0476 (13) | 0.0026 (9) | 0.0060 (9) | 0.0277 (12) |
C18 | 0.0256 (9) | 0.0586 (13) | 0.0443 (14) | 0.0055 (8) | 0.0017 (9) | 0.0266 (12) |
C12 | 0.0189 (7) | 0.0298 (8) | 0.0344 (10) | 0.0015 (6) | −0.0019 (8) | −0.0029 (8) |
Geometric parameters (Å, º) top
O1—C1 | 1.273 (2) | C7—H7 | 0.97 (3) |
O1—H20 | 1.47 (4) | C8—C9 | 1.385 (3) |
O2—C3 | 1.318 (2) | C8—H8 | 0.96 (2) |
O2—H20 | 1.08 (4) | C9—C10 | 1.421 (2) |
O3—C10 | 1.367 (2) | C10—C11 | 1.377 (2) |
O3—C12 | 1.4344 (19) | C11—H11 | 0.98 (2) |
O4—C9 | 1.356 (2) | C13—C14 | 1.390 (3) |
O4—H40 | 0.84 (3) | C13—C18 | 1.390 (3) |
C1—C2 | 1.417 (3) | C14—C15 | 1.392 (3) |
C1—C13 | 1.498 (2) | C14—H14 | 0.97 (3) |
C2—C3 | 1.391 (2) | C15—C16 | 1.379 (3) |
C2—H2 | 0.97 (3) | C15—H15 | 1.03 (4) |
C3—C4 | 1.451 (2) | C16—C17 | 1.373 (3) |
C4—C5 | 1.349 (2) | C16—H16 | 0.97 (2) |
C4—H4 | 0.94 (3) | C17—C18 | 1.396 (3) |
C5—C6 | 1.463 (2) | C17—H17 | 0.97 (3) |
C5—H5 | 0.94 (2) | C18—H18 | 1.00 (3) |
C6—C7 | 1.402 (2) | C12—H122 | 0.97 (3) |
C6—C11 | 1.407 (3) | C12—H123 | 0.98 (2) |
C7—C8 | 1.395 (3) | C12—H121 | 0.99 (3) |
| | | |
C1—O1—H20 | 100.8 (19) | O3—C10—C11 | 125.59 (15) |
C3—O2—H20 | 103 (2) | O3—C10—C9 | 114.66 (15) |
C10—O3—C12 | 116.64 (14) | C11—C10—C9 | 119.75 (17) |
C9—O4—H40 | 111.2 (19) | C10—C11—C6 | 121.21 (15) |
O1—C1—C2 | 120.50 (15) | C10—C11—H11 | 117.0 (13) |
O1—C1—C13 | 118.07 (16) | C6—C11—H11 | 121.8 (14) |
C2—C1—C13 | 121.42 (17) | C14—C13—C18 | 118.70 (16) |
C3—C2—C1 | 120.62 (17) | C14—C13—C1 | 122.28 (17) |
C3—C2—H2 | 118.4 (13) | C18—C13—C1 | 119.02 (16) |
C1—C2—H2 | 121.0 (13) | C13—C14—C15 | 120.52 (19) |
O2—C3—C2 | 120.99 (16) | C13—C14—H14 | 121.0 (17) |
O2—C3—C4 | 117.82 (15) | C15—C14—H14 | 118.3 (17) |
C2—C3—C4 | 121.19 (17) | C16—C15—C14 | 120.1 (2) |
C5—C4—C3 | 123.56 (18) | C16—C15—H15 | 120.1 (17) |
C5—C4—H4 | 120.4 (13) | C14—C15—H15 | 119.8 (17) |
C3—C4—H4 | 116.0 (13) | C17—C16—C15 | 120.11 (17) |
C4—C5—C6 | 125.71 (18) | C17—C16—H16 | 120.0 (15) |
C4—C5—H5 | 120.5 (13) | C15—C16—H16 | 119.8 (15) |
C6—C5—H5 | 113.7 (13) | C16—C17—C18 | 120.1 (2) |
C7—C6—C11 | 118.58 (16) | C16—C17—H17 | 117.5 (18) |
C7—C6—C5 | 120.15 (17) | C18—C17—H17 | 122.3 (18) |
C11—C6—C5 | 121.23 (15) | C13—C18—C17 | 120.45 (19) |
C8—C7—C6 | 120.44 (18) | C13—C18—H18 | 119.5 (17) |
C8—C7—H7 | 121.2 (13) | C17—C18—H18 | 119.9 (17) |
C6—C7—H7 | 118.4 (13) | O3—C12—H122 | 105.9 (14) |
C9—C8—C7 | 120.68 (16) | O3—C12—H123 | 110.0 (13) |
C9—C8—H8 | 120.4 (14) | H122—C12—H123 | 112 (2) |
C7—C8—H8 | 118.9 (14) | O3—C12—H121 | 106.1 (13) |
O4—C9—C8 | 119.89 (15) | H122—C12—H121 | 106.2 (18) |
O4—C9—C10 | 120.82 (17) | H123—C12—H121 | 116.1 (19) |
C8—C9—C10 | 119.29 (17) | | |
| | | |
O1—C1—C2—C3 | 0.5 (3) | O4—C9—C10—C11 | 179.24 (16) |
C13—C1—C2—C3 | 179.76 (16) | C8—C9—C10—C11 | −1.2 (3) |
C1—C2—C3—O2 | 0.3 (3) | O3—C10—C11—C6 | −177.49 (15) |
C1—C2—C3—C4 | −178.57 (16) | C9—C10—C11—C6 | 2.1 (2) |
O2—C3—C4—C5 | −4.1 (3) | C7—C6—C11—C10 | −1.2 (2) |
C2—C3—C4—C5 | 174.85 (17) | C5—C6—C11—C10 | 176.57 (16) |
C3—C4—C5—C6 | −175.03 (16) | O1—C1—C13—C14 | 166.88 (19) |
C4—C5—C6—C7 | −175.66 (17) | C2—C1—C13—C14 | −12.4 (3) |
C4—C5—C6—C11 | 6.6 (3) | O1—C1—C13—C18 | −12.3 (3) |
C11—C6—C7—C8 | −0.7 (3) | C2—C1—C13—C18 | 168.4 (2) |
C5—C6—C7—C8 | −178.47 (16) | C18—C13—C14—C15 | −0.2 (3) |
C6—C7—C8—C9 | 1.6 (3) | C1—C13—C14—C15 | −179.4 (2) |
C7—C8—C9—O4 | 178.91 (17) | C13—C14—C15—C16 | −0.2 (4) |
C7—C8—C9—C10 | −0.7 (3) | C14—C15—C16—C17 | 0.0 (4) |
C12—O3—C10—C11 | 4.3 (2) | C15—C16—C17—C18 | 0.6 (4) |
C12—O3—C10—C9 | −175.37 (15) | C14—C13—C18—C17 | 0.8 (4) |
O4—C9—C10—O3 | −1.1 (2) | C1—C13—C18—C17 | 180.0 (2) |
C8—C9—C10—O3 | 178.46 (16) | C16—C17—C18—C13 | −1.0 (4) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O2—H20···O1 | 1.08 (4) | 1.47 (4) | 2.4875 (19) | 154 (4) |
O4—H40···O3 | 0.84 (3) | 2.25 (3) | 2.6876 (17) | 112 (2) |
O4—H40···O1i | 0.84 (3) | 2.04 (3) | 2.840 (2) | 159 (3) |
C12—H122···O2i | 0.97 (3) | 2.38 (3) | 3.221 (3) | 145.0 (19) |
C18—H18···O4ii | 1.00 (3) | 2.48 (3) | 3.461 (3) | 167 (2) |
C8—H8···O4iii | 0.96 (2) | 2.71 (2) | 3.493 (2) | 140.0 (16) |
Symmetry codes: (i) −x+1/2, y+1/2, z−3/2; (ii) −x+1/2, y−1/2, z+3/2; (iii) −x+1, −y+2, z+1/2. |