Buy article online - an online subscription or single-article purchase is required to access this article.
α-Oxobenzeneacetic (phenylglyoxylic) acid, C
8H
6O
3, adopts a
transoid dicarbonyl conformation in the solid state, with the carboxyl group rotated 44.4 (1)° from the nearly planar benzoyl moiety. The heterochiral acid-to-ketone catemers [O
O = 2.686 (3) and H
O = 1.78 (4) Å] have a second, longer, intermolecular O—H
O contact to a carboxyl
sp3 O atom [O
O = 3.274 (2) and H
O = 2.72 (4) Å], with each flat ribbon-like chain lying in the
bc plane and extending in the
c direction. In α-oxo-2,4,6-trimethylbenzeneacetic (mesitylglyoxylic) acid, C
11H
12O
3, the ketone is rotated 49.1 (7)° from planarity with the aryl ring and the carboxyl group is rotated a further 31.2 (7)° from the ketone plane. The solid consists of chiral conformers of a single handedness, aggregating in hydrogen-bonding chains whose units are related by a 3
1 screw axis, producing hydrogen-bonding helices that extend in the
c direction. The hydrogen bonding is of the acid-to-acid type [O
O = 2.709 (6) and H
O = 1.87 (5) Å] and does not formally involve the ketone; however, the ketone O atom in the acceptor molecule has a close polar contact with the same donor carboxyl group [O
O = 3.005 (6) and H
O = 2.50 (5) Å]. This secondary hydrogen bond is probably a major factor in stabilizing the observed
cisoid dicarbonyl conformation. Several intermolecular C—H
O close contacts were found for the latter compound.
Supporting information
CCDC references: 150856; 150857
For both compounds, data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
(I)
α-Oxobenzeneacetic acid
top
Crystal data top
C8H6O3 | Dx = 1.381 Mg m−3 |
Mr = 150.13 | Melting point: 342 K |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 7.462 (2) Å | Cell parameters from 15 reflections |
b = 16.513 (5) Å | θ = 3.2–12.3° |
c = 6.483 (3) Å | µ = 0.11 mm−1 |
β = 115.32 (2)° | T = 293 K |
V = 722.1 (4) Å3 | Parallelepiped, colorless |
Z = 4 | 0.64 × 0.50 × 0.30 mm |
F(000) = 312 | |
Data collection top
Siemens P4 diffractometer | Rint = 0.022 |
Radiation source: normal-focus sealed tube | θmax = 25.0°, θmin = 2.5° |
Graphite monochromator | h = −8→8 |
2θ–θ scans | k = −1→19 |
1562 measured reflections | l = −1→7 |
1271 independent reflections | 3 standard reflections every 97 reflections |
740 reflections with I > 2σ(I) | intensity decay: variation < 1.8% |
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)] = 0.059 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.153 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0743P)2] where P = (Fo2 + 2Fc2)/3 |
1271 reflections | (Δ/σ)max < 0.001 |
105 parameters | Δρmax = 0.20 e Å−3 |
0 restraints | Δρmin = −0.19 e Å−3 |
Special details top
Experimental. Crystal mounted in glass capillary and coated with grease |
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 | 0.1528 (4) | 0.62379 (13) | 0.4709 (4) | 0.0711 (7) | |
O2 | 0.3784 (4) | 0.68636 (14) | 0.1497 (4) | 0.0777 (8) | |
O3 | 0.0991 (3) | 0.73600 (13) | 0.1469 (4) | 0.0667 (7) | |
H3 | 0.125 (6) | 0.780 (3) | 0.075 (7) | 0.123 (16)* | |
C1 | 0.2363 (4) | 0.52537 (16) | 0.2631 (5) | 0.0510 (8) | |
C2 | 0.2801 (5) | 0.50725 (19) | 0.0795 (6) | 0.0617 (9) | |
C3 | 0.3127 (5) | 0.4272 (2) | 0.0415 (7) | 0.0761 (11) | |
C4 | 0.3020 (5) | 0.3672 (2) | 0.1792 (8) | 0.0807 (12) | |
C5 | 0.2541 (5) | 0.3844 (2) | 0.3572 (7) | 0.0808 (12) | |
C6 | 0.2219 (5) | 0.46344 (18) | 0.3989 (6) | 0.0645 (9) | |
C7 | 0.2028 (4) | 0.60937 (17) | 0.3189 (5) | 0.0523 (8) | |
C8 | 0.2376 (5) | 0.68093 (17) | 0.1917 (5) | 0.0555 (8) | |
H2 | 0.2872 | 0.5481 | −0.0155 | 0.085 (5)* | |
H3A | 0.3424 | 0.4143 | −0.0801 | 0.085 (5)* | |
H4 | 0.3274 | 0.3140 | 0.1530 | 0.085 (5)* | |
H5 | 0.2436 | 0.3430 | 0.4485 | 0.085 (5)* | |
H6 | 0.1901 | 0.4754 | 0.5195 | 0.085 (5)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.1039 (18) | 0.0484 (13) | 0.0811 (16) | −0.0081 (11) | 0.0588 (15) | −0.0032 (12) |
O2 | 0.0759 (16) | 0.0660 (15) | 0.108 (2) | 0.0024 (12) | 0.0554 (15) | 0.0166 (13) |
O3 | 0.0732 (15) | 0.0471 (12) | 0.0856 (18) | 0.0051 (11) | 0.0396 (13) | 0.0091 (12) |
C1 | 0.0442 (17) | 0.0442 (16) | 0.058 (2) | −0.0009 (13) | 0.0156 (15) | 0.0034 (15) |
C2 | 0.058 (2) | 0.059 (2) | 0.069 (2) | −0.0046 (15) | 0.0283 (18) | −0.0027 (17) |
C3 | 0.067 (2) | 0.069 (2) | 0.088 (3) | 0.0021 (19) | 0.029 (2) | −0.023 (2) |
C4 | 0.064 (2) | 0.044 (2) | 0.119 (4) | 0.0031 (16) | 0.025 (2) | −0.010 (2) |
C5 | 0.083 (3) | 0.0471 (19) | 0.103 (3) | −0.0015 (18) | 0.031 (2) | 0.014 (2) |
C6 | 0.067 (2) | 0.0499 (18) | 0.074 (2) | −0.0034 (15) | 0.0280 (19) | 0.0026 (17) |
C7 | 0.0517 (18) | 0.0452 (17) | 0.061 (2) | −0.0049 (13) | 0.0250 (16) | 0.0012 (16) |
C8 | 0.0580 (19) | 0.0433 (16) | 0.065 (2) | −0.0037 (15) | 0.0262 (17) | −0.0020 (15) |
Geometric parameters (Å, º) top
O1—C7 | 1.217 (3) | C2—C3 | 1.386 (4) |
O2—C8 | 1.196 (3) | C3—C4 | 1.358 (5) |
O3—C8 | 1.312 (4) | C4—C5 | 1.376 (5) |
C1—C6 | 1.383 (4) | C5—C6 | 1.374 (5) |
C1—C2 | 1.395 (4) | C7—C8 | 1.525 (4) |
C1—C7 | 1.481 (4) | | |
| | | |
C6—C1—C2 | 119.7 (3) | C5—C6—C1 | 120.6 (3) |
C6—C1—C7 | 118.0 (3) | O1—C7—C1 | 121.5 (3) |
C2—C1—C7 | 122.3 (3) | O1—C7—C8 | 117.9 (3) |
C3—C2—C1 | 118.7 (3) | C1—C7—C8 | 120.6 (3) |
C4—C3—C2 | 121.0 (4) | O2—C8—O3 | 125.7 (3) |
C3—C4—C5 | 120.7 (3) | O2—C8—C7 | 123.4 (3) |
C6—C5—C4 | 119.4 (3) | O3—C8—C7 | 110.9 (3) |
| | | |
C6—C1—C2—C3 | −1.5 (5) | C6—C1—C7—O1 | −4.2 (4) |
C7—C1—C2—C3 | 178.9 (3) | C2—C1—C7—O1 | 175.4 (3) |
C1—C2—C3—C4 | 0.2 (5) | C6—C1—C7—C8 | 173.6 (3) |
C2—C3—C4—C5 | 1.4 (5) | C2—C1—C7—C8 | −6.8 (4) |
C3—C4—C5—C6 | −1.7 (5) | O1—C7—C8—O2 | 134.3 (3) |
C4—C5—C6—C1 | 0.3 (5) | C1—C7—C8—O2 | −43.6 (4) |
C2—C1—C6—C5 | 1.3 (5) | O1—C7—C8—O3 | −42.5 (4) |
C7—C1—C6—C5 | −179.1 (3) | C1—C7—C8—O3 | 139.6 (3) |
(II)
α-oxo-2,4,6-trimethylbenzeneacetic acid
top
Crystal data top
C11H12O3 | Dx = 1.257 Mg m−3 |
Mr = 192.21 | Melting point: 392 K |
Trigonal, P31 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 31 | Cell parameters from 17 reflections |
a = 9.121 (1) Å | θ = 5.6–12.0° |
c = 10.576 (1) Å | µ = 0.09 mm−1 |
V = 761.97 (14) Å3 | T = 248 K |
Z = 3 | Block, colorless |
F(000) = 306 | 0.30 × 0.28 × 0.26 mm |
Data collection top
Siemens P4 diffractometer | 574 reflections with I > 2σ(I) |
Radiation source: normal-focus sealed tube | Rint = 0.046 |
Graphite monochromator | θmax = 25.0°, θmin = 2.6° |
2θ–θ scans | h = −10→10 |
Absorption correction: numerical (SHELXTL; Sheldrick, 1997) | k = 0→10 |
Tmin = 0.967, Tmax = 0.977 | l = 0→12 |
2050 measured reflections | 3 standard reflections every 97 reflections |
1772 independent reflections | intensity decay: variation < 3.3% |
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)] = 0.049 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.127 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0648P)2] where P = (Fo2 + 2Fc2)/3 |
886 reflections | (Δ/σ)max < 0.001 |
141 parameters | Δρmax = 0.13 e Å−3 |
1 restraint | Δρmin = −0.18 e Å−3 |
Special details top
Experimental. Crystal mounted on glass fiber using epoxy cement |
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 with 886 Friedel pairs merged.
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 | Occ. (<1) |
O1 | 0.6580 (6) | 0.8177 (6) | 0.2937 (4) | 0.0803 (14) | |
O2 | 0.3786 (5) | 0.7123 (5) | 0.1425 (4) | 0.0607 (10) | |
O3 | 0.5133 (5) | 0.6231 (5) | 0.0138 (3) | 0.0538 (10) | |
H3 | 0.434 (6) | 0.615 (5) | −0.039 (5) | 0.031 (13)* | |
C1 | 0.6922 (7) | 0.5872 (7) | 0.2251 (5) | 0.0493 (15) | |
C2 | 0.8699 (7) | 0.6594 (7) | 0.2300 (5) | 0.0529 (14) | |
C3 | 0.9367 (8) | 0.5533 (9) | 0.2347 (5) | 0.0647 (17) | |
C4 | 0.8351 (9) | 0.3801 (9) | 0.2392 (5) | 0.0595 (16) | |
C5 | 0.6630 (8) | 0.3119 (8) | 0.2361 (5) | 0.0591 (17) | |
C6 | 0.5883 (7) | 0.4115 (7) | 0.2286 (5) | 0.0502 (15) | |
C7 | 0.6204 (7) | 0.6998 (7) | 0.2226 (5) | 0.0527 (14) | |
C8 | 0.4881 (7) | 0.6756 (7) | 0.1218 (5) | 0.0504 (13) | |
C9 | 0.9885 (8) | 0.8482 (8) | 0.2232 (6) | 0.075 (2) | |
C10 | 0.9125 (11) | 0.2667 (11) | 0.2484 (7) | 0.089 (2) | |
C11 | 0.3965 (8) | 0.3292 (8) | 0.2295 (5) | 0.0669 (18) | |
H3A | 1.0549 | 0.6005 | 0.2347 | 0.065 (19)* | |
H5 | 0.5934 | 0.1936 | 0.2392 | 0.031 (13)* | |
H9A | 1.0995 | 0.8707 | 0.1961 | 0.091 (19)* | 0.77 (8) |
H9B | 0.9972 | 0.8978 | 0.3059 | 0.091 (19)* | 0.77 (8) |
H9C | 0.9451 | 0.8974 | 0.1630 | 0.091 (19)* | 0.77 (8) |
H9D | 0.9283 | 0.9065 | 0.2472 | 0.091 (19)* | 0.23 (8) |
H9E | 1.0307 | 0.8795 | 0.1375 | 0.091 (19)* | 0.23 (8) |
H9F | 1.0828 | 0.8799 | 0.2804 | 0.091 (19)* | 0.23 (8) |
H10A | 0.8229 | 0.1493 | 0.2523 | 0.092 (19)* | 0.75 (8) |
H10B | 0.9815 | 0.2949 | 0.3240 | 0.092 (19)* | 0.75 (8) |
H10C | 0.9824 | 0.2835 | 0.1746 | 0.092 (19)* | 0.75 (8) |
H10D | 1.0349 | 0.3358 | 0.2483 | 0.092 (19)* | 0.25 (8) |
H10E | 0.8764 | 0.1902 | 0.1766 | 0.092 (19)* | 0.25 (8) |
H10F | 0.8755 | 0.2016 | 0.3260 | 0.092 (19)* | 0.25 (8) |
H11A | 0.3474 | 0.2167 | 0.2658 | 0.063 (10)* | |
H11B | 0.3559 | 0.3211 | 0.1436 | 0.063 (10)* | |
H11C | 0.3638 | 0.3972 | 0.2797 | 0.063 (10)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.098 (3) | 0.087 (3) | 0.076 (3) | 0.061 (3) | −0.029 (2) | −0.038 (3) |
O2 | 0.061 (2) | 0.084 (3) | 0.049 (2) | 0.045 (2) | −0.002 (2) | −0.007 (2) |
O3 | 0.053 (2) | 0.072 (3) | 0.0382 (18) | 0.033 (2) | −0.0096 (18) | −0.0090 (18) |
C1 | 0.052 (4) | 0.055 (4) | 0.036 (3) | 0.023 (3) | −0.002 (3) | −0.003 (2) |
C2 | 0.052 (4) | 0.060 (4) | 0.044 (3) | 0.026 (3) | −0.009 (3) | −0.001 (3) |
C3 | 0.055 (4) | 0.090 (5) | 0.053 (4) | 0.039 (4) | 0.002 (3) | 0.011 (3) |
C4 | 0.076 (5) | 0.071 (5) | 0.044 (3) | 0.046 (4) | 0.004 (3) | 0.008 (3) |
C5 | 0.077 (5) | 0.055 (4) | 0.034 (3) | 0.025 (4) | 0.001 (3) | 0.006 (3) |
C6 | 0.048 (3) | 0.057 (4) | 0.032 (3) | 0.016 (3) | 0.001 (2) | 0.004 (3) |
C7 | 0.064 (4) | 0.057 (4) | 0.040 (3) | 0.032 (3) | 0.001 (3) | −0.007 (3) |
C8 | 0.047 (3) | 0.055 (3) | 0.045 (3) | 0.023 (3) | 0.001 (3) | −0.001 (3) |
C9 | 0.059 (4) | 0.069 (5) | 0.085 (5) | 0.024 (4) | −0.014 (3) | 0.001 (3) |
C10 | 0.119 (6) | 0.118 (6) | 0.067 (5) | 0.086 (6) | 0.019 (4) | 0.022 (4) |
C11 | 0.062 (4) | 0.065 (4) | 0.049 (4) | 0.014 (3) | 0.005 (3) | 0.014 (3) |
Geometric parameters (Å, º) top
O1—C7 | 1.213 (6) | C2—C9 | 1.509 (9) |
O2—C8 | 1.221 (6) | C3—C4 | 1.375 (9) |
O3—C8 | 1.303 (6) | C4—C5 | 1.369 (9) |
C1—C6 | 1.396 (7) | C4—C10 | 1.519 (9) |
C1—C2 | 1.412 (8) | C5—C6 | 1.384 (9) |
C1—C7 | 1.469 (8) | C6—C11 | 1.520 (9) |
C2—C3 | 1.380 (8) | C7—C8 | 1.541 (8) |
| | | |
C6—C1—C2 | 119.8 (5) | C4—C5—C6 | 122.1 (6) |
C6—C1—C7 | 121.2 (5) | C5—C6—C1 | 118.7 (5) |
C2—C1—C7 | 118.9 (5) | C5—C6—C11 | 119.9 (5) |
C3—C2—C1 | 118.7 (6) | C1—C6—C11 | 121.4 (6) |
C3—C2—C9 | 119.1 (6) | O1—C7—C1 | 125.5 (5) |
C1—C2—C9 | 122.1 (5) | O1—C7—C8 | 114.3 (5) |
C4—C3—C2 | 121.8 (6) | C1—C7—C8 | 120.2 (5) |
C5—C4—C3 | 118.8 (6) | O2—C8—O3 | 125.2 (5) |
C5—C4—C10 | 120.6 (7) | O2—C8—C7 | 121.7 (5) |
C3—C4—C10 | 120.5 (6) | O3—C8—C7 | 113.0 (5) |
| | | |
C6—C1—C2—C3 | 1.8 (6) | C2—C1—C6—C5 | −0.4 (6) |
C7—C1—C2—C3 | 178.9 (5) | C7—C1—C6—C5 | −177.4 (5) |
C6—C1—C2—C9 | 178.4 (5) | C2—C1—C6—C11 | 177.2 (5) |
C7—C1—C2—C9 | −4.6 (7) | C7—C1—C6—C11 | 0.2 (7) |
C1—C2—C3—C4 | −2.4 (7) | C6—C1—C7—O1 | 128.0 (6) |
C9—C2—C3—C4 | −179.1 (5) | C2—C1—C7—O1 | −49.0 (8) |
C2—C3—C4—C5 | 1.5 (8) | C6—C1—C7—C8 | −53.4 (7) |
C2—C3—C4—C10 | −178.1 (5) | C2—C1—C7—C8 | 129.6 (5) |
C3—C4—C5—C6 | 0.0 (8) | O1—C7—C8—O2 | −31.4 (8) |
C10—C4—C5—C6 | 179.6 (5) | C1—C7—C8—O2 | 149.8 (5) |
C4—C5—C6—C1 | −0.5 (7) | O1—C7—C8—O3 | 144.8 (5) |
C4—C5—C6—C11 | −178.2 (5) | C1—C7—C8—O3 | −34.0 (7) |
Subscribe to Acta Crystallographica Section C: Structural Chemistry
The full text of this article is available to subscribers to the journal.
If you have already registered and are using a computer listed in your registration details, please email
support@iucr.org for assistance.