Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802015672/ya6128sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536802015672/ya6128Isup2.hkl |
CCDC reference: 198330
Key indicators
- Single-crystal X-ray study
- T = 293 K
- Mean (C-C) = 0.003 Å
- R factor = 0.062
- wR factor = 0.176
- Data-to-parameter ratio = 12.8
checkCIF results
No syntax errors found ADDSYM reports no extra symmetry
Alert Level C:
ABSMU_01 Alert C The ratio of given/expected absorption coefficient lies outside the range 0.99 <> 1.01 Calculated value of mu = 0.093 Value of mu given = 0.090 RINTA_01 Alert C The value of Rint is greater than 0.10 Rint given 0.116 PLAT_320 Alert C Check Hybridisation of C(10) in main residue ?
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
3 Alert Level C = Please check
The title compound was prepared by photoinduced reactions of 1-acetylisatin (0.05 mol l−1) with an excess of bicyclopropylidene in benzene solution, and isolated by column chromatography on silica gel (Wang & Xu, 2002). Single crystals suitable for X-ray diffraction analysis were obtained by slow evaporation from an acetone–petroleum ether (1:5 v/v) solution.
The H atoms were fixed geometrically and treated as riding on their parent C atoms, with C—H distances = 0.93–0.97 Å and Uiso(H) = 1.2Ueq(C) [1.5Ueq(C) for the H atoms of the mrthyl group].
Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT and SADABS (Sheldrick, 1996); 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, PARST (Nardelli, 1995) and PLATON (Spek, 1990).
Fig. 1. The structure of title compound, showing 50% probability displacement ellipsoids and the atom-numbering scheme. |
C16H15NO3 | Dx = 1.338 Mg m−3 |
Mr = 269.29 | Melting point: 410(1) K |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 10.4584 (1) Å | Cell parameters from 5107 reflections |
b = 9.2661 (2) Å | θ = 2.6–28.3° |
c = 13.7923 (3) Å | µ = 0.09 mm−1 |
β = 90.329 (1)° | T = 293 K |
V = 1336.57 (4) Å3 | Block, colorless |
Z = 4 | 0.46 × 0.32 × 0.22 mm |
F(000) = 568 |
Siemens SMART CCD area-detector diffractometer | 1656 reflections with I > 2σ(I)' |
Radiation source: fine-focus sealed tube | Rint = 0.116 |
Graphite monochromator | θmax = 25.0°, θmin = 2.6° |
Detector resolution: 8.33 pixels mm-1 | h = −12→5 |
ω scans | k = −10→11 |
6266 measured reflections | l = −16→16 |
2346 independent reflections |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.062 | H-atom parameters constrained |
wR(F2) = 0.176 | w = 1/[σ2(Fo2) + (0.0865P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.99 | (Δ/σ)max < 0.001 |
2346 reflections | Δρmax = 0.30 e Å−3 |
183 parameters | Δρmin = −0.40 e Å−3 |
0 restraints | Extinction correction: SHELXTL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.130 (16) |
C16H15NO3 | V = 1336.57 (4) Å3 |
Mr = 269.29 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 10.4584 (1) Å | µ = 0.09 mm−1 |
b = 9.2661 (2) Å | T = 293 K |
c = 13.7923 (3) Å | 0.46 × 0.32 × 0.22 mm |
β = 90.329 (1)° |
Siemens SMART CCD area-detector diffractometer | 1656 reflections with I > 2σ(I)' |
6266 measured reflections | Rint = 0.116 |
2346 independent reflections |
R[F2 > 2σ(F2)] = 0.062 | 0 restraints |
wR(F2) = 0.176 | H-atom parameters constrained |
S = 0.99 | Δρmax = 0.30 e Å−3 |
2346 reflections | Δρmin = −0.40 e Å−3 |
183 parameters |
Experimental. The data collection covered over a hemisphere of reciprocal space by a combination of three sets of exposures; each set had a different ϕ angle (0, 88 and 180°) for the crystal and each exposure of 30 s covered 0.3° in ω. The crystal-to-detector distance was 5 cm and the detector swing angle was −35°. Crystal decay was monitored by repeating fifty initial frames at the end of data collection and analysing the intensity of duplicate reflections, and was found to be negligible. |
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 | 0.42348 (16) | 0.40961 (16) | 0.61325 (15) | 0.0553 (6) | |
O2 | 0.73563 (16) | 0.13267 (19) | 0.60286 (15) | 0.0577 (6) | |
O3 | 0.24733 (14) | 0.23422 (17) | 0.73731 (12) | 0.0445 (5) | |
N1 | 0.52489 (16) | 0.18522 (18) | 0.61536 (12) | 0.0318 (5) | |
C1 | 0.4204 (2) | 0.2797 (2) | 0.62129 (17) | 0.0370 (6) | |
C2 | 0.3012 (2) | 0.1902 (2) | 0.64355 (16) | 0.0366 (6) | |
C3 | 0.3496 (2) | 0.0397 (2) | 0.64152 (16) | 0.0357 (6) | |
C4 | 0.2826 (2) | −0.0881 (2) | 0.65425 (18) | 0.0466 (7) | |
H4A | 0.1947 | −0.0880 | 0.6642 | 0.056* | |
C5 | 0.3517 (3) | −0.2167 (2) | 0.65154 (19) | 0.0499 (7) | |
H5A | 0.3093 | −0.3043 | 0.6585 | 0.060* | |
C6 | 0.4815 (3) | −0.2156 (2) | 0.63883 (18) | 0.0455 (7) | |
H6A | 0.5256 | −0.3027 | 0.6379 | 0.055* | |
C7 | 0.5485 (2) | −0.0882 (2) | 0.62727 (17) | 0.0410 (6) | |
H7A | 0.6368 | −0.0885 | 0.6195 | 0.049* | |
C8 | 0.4805 (2) | 0.0394 (2) | 0.62758 (14) | 0.0308 (5) | |
C9 | 0.1767 (2) | 0.2367 (2) | 0.59336 (18) | 0.0385 (6) | |
C10 | 0.1349 (2) | 0.2905 (2) | 0.69025 (18) | 0.0406 (6) | |
C11 | 0.0797 (3) | 0.4301 (3) | 0.7173 (2) | 0.0670 (9) | |
H11A | 0.1183 | 0.4818 | 0.7712 | 0.080* | |
H11B | 0.0457 | 0.4907 | 0.6659 | 0.080* | |
C12 | 0.0099 (3) | 0.2883 (3) | 0.7393 (2) | 0.0587 (8) | |
H12A | 0.0074 | 0.2558 | 0.8061 | 0.070* | |
H12B | −0.0651 | 0.2647 | 0.7008 | 0.070* | |
C13 | 0.1573 (3) | 0.2996 (3) | 0.49436 (19) | 0.0531 (7) | |
H13A | 0.2301 | 0.3016 | 0.4511 | 0.064* | |
H13B | 0.0994 | 0.3808 | 0.4879 | 0.064* | |
C14 | 0.1011 (3) | 0.1553 (3) | 0.5191 (2) | 0.0536 (7) | |
H14A | 0.0093 | 0.1495 | 0.5275 | 0.064* | |
H14B | 0.1400 | 0.0703 | 0.4906 | 0.064* | |
C15 | 0.6532 (2) | 0.2242 (3) | 0.60118 (17) | 0.0390 (6) | |
C16 | 0.6844 (3) | 0.3794 (3) | 0.5834 (2) | 0.0558 (8) | |
H16A | 0.7748 | 0.3895 | 0.5736 | 0.084* | |
H16B | 0.6591 | 0.4358 | 0.6384 | 0.084* | |
H16C | 0.6394 | 0.4124 | 0.5268 | 0.084* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0502 (12) | 0.0283 (10) | 0.0874 (15) | −0.0006 (7) | 0.0004 (10) | 0.0050 (8) |
O2 | 0.0381 (11) | 0.0510 (11) | 0.0840 (14) | 0.0039 (9) | −0.0024 (9) | 0.0058 (10) |
O3 | 0.0344 (10) | 0.0578 (11) | 0.0413 (10) | 0.0056 (8) | −0.0006 (7) | −0.0083 (7) |
N1 | 0.0320 (11) | 0.0282 (10) | 0.0351 (10) | −0.0017 (7) | −0.0010 (8) | 0.0026 (7) |
C1 | 0.0386 (14) | 0.0297 (12) | 0.0427 (14) | −0.0004 (9) | −0.0043 (10) | 0.0010 (9) |
C2 | 0.0346 (13) | 0.0332 (12) | 0.0420 (13) | 0.0019 (10) | −0.0031 (10) | −0.0026 (10) |
C3 | 0.0410 (14) | 0.0302 (12) | 0.0360 (12) | −0.0009 (10) | −0.0039 (10) | 0.0040 (9) |
C4 | 0.0471 (16) | 0.0395 (14) | 0.0532 (16) | −0.0118 (11) | −0.0029 (12) | 0.0064 (11) |
C5 | 0.071 (2) | 0.0287 (13) | 0.0494 (16) | −0.0106 (12) | −0.0095 (13) | 0.0077 (10) |
C6 | 0.0624 (18) | 0.0318 (13) | 0.0424 (14) | 0.0042 (11) | −0.0044 (12) | 0.0043 (10) |
C7 | 0.0470 (16) | 0.0348 (13) | 0.0412 (14) | 0.0055 (11) | −0.0025 (11) | 0.0021 (10) |
C8 | 0.0372 (13) | 0.0287 (12) | 0.0266 (11) | −0.0021 (9) | −0.0028 (9) | 0.0028 (8) |
C9 | 0.0349 (13) | 0.0297 (12) | 0.0507 (15) | 0.0005 (9) | −0.0085 (10) | −0.0014 (10) |
C10 | 0.0344 (13) | 0.0374 (13) | 0.0499 (15) | 0.0039 (10) | −0.0018 (11) | −0.0059 (10) |
C11 | 0.081 (2) | 0.0436 (16) | 0.076 (2) | 0.0188 (14) | −0.0111 (17) | −0.0167 (14) |
C12 | 0.0395 (16) | 0.0607 (19) | 0.076 (2) | 0.0094 (13) | 0.0004 (14) | −0.0118 (15) |
C13 | 0.0533 (17) | 0.0523 (16) | 0.0536 (17) | −0.0009 (13) | −0.0103 (13) | 0.0071 (12) |
C14 | 0.0484 (16) | 0.0458 (15) | 0.0664 (18) | −0.0051 (12) | −0.0146 (13) | −0.0105 (13) |
C15 | 0.0348 (14) | 0.0414 (14) | 0.0408 (13) | −0.0037 (11) | −0.0066 (10) | 0.0045 (10) |
C16 | 0.0463 (16) | 0.0455 (16) | 0.075 (2) | −0.0163 (12) | −0.0095 (14) | 0.0141 (13) |
O1—C1 | 1.209 (2) | C9—C10 | 1.494 (3) |
O2—C15 | 1.209 (3) | C9—C14 | 1.494 (3) |
O3—C2 | 1.471 (3) | C9—C13 | 1.497 (3) |
O3—C10 | 1.438 (3) | C10—C11 | 1.466 (3) |
N1—C1 | 1.404 (3) | C10—C12 | 1.476 (4) |
N1—C15 | 1.404 (3) | C11—C12 | 1.535 (4) |
N1—C8 | 1.438 (3) | C11—H11B | 0.9700 |
C1—C2 | 1.529 (3) | C11—H11A | 0.9700 |
C2—C3 | 1.484 (3) | C12—H12A | 0.9700 |
C2—C9 | 1.533 (3) | C12—H12B | 0.9700 |
C3—C8 | 1.384 (3) | C13—C14 | 1.501 (4) |
C3—C4 | 1.389 (3) | C13—H13A | 0.9700 |
C4—C5 | 1.395 (3) | C13—H13B | 0.9700 |
C4—H4A | 0.9300 | C14—H14A | 0.9700 |
C5—C6 | 1.369 (4) | C14—H14B | 0.9700 |
C5—H5A | 0.9300 | C15—C16 | 1.495 (3) |
C6—C7 | 1.382 (3) | C16—H16A | 0.9600 |
C6—H6A | 0.9300 | C16—H16B | 0.9600 |
C7—C8 | 1.380 (3) | C16—H16C | 0.9600 |
C7—H7A | 0.9300 | ||
C10—O3—C2 | 91.15 (16) | O3—C10—C12 | 120.8 (2) |
C1—N1—C15 | 126.37 (18) | C11—C10—C12 | 62.89 (19) |
C1—N1—C8 | 109.11 (17) | O3—C10—C9 | 92.30 (17) |
C15—N1—C8 | 124.52 (18) | C11—C10—C9 | 129.8 (2) |
O1—C1—N1 | 126.5 (2) | C12—C10—C9 | 132.0 (2) |
O1—C1—C2 | 125.5 (2) | C10—C11—C12 | 58.87 (17) |
N1—C1—C2 | 108.00 (17) | C10—C11—H11B | 117.9 |
O3—C2—C3 | 114.16 (18) | C12—C11—H11B | 117.9 |
O3—C2—C1 | 110.05 (17) | C10—C11—H11A | 117.9 |
C3—C2—C1 | 103.15 (18) | C12—C11—H11A | 117.9 |
O3—C2—C9 | 89.44 (16) | H11B—C11—H11A | 115.0 |
C3—C2—C9 | 122.98 (19) | C10—C12—C11 | 58.24 (17) |
C1—C2—C9 | 116.63 (19) | C10—C12—H12A | 117.9 |
C8—C3—C4 | 121.1 (2) | C11—C12—H12A | 117.9 |
C8—C3—C2 | 110.02 (18) | C10—C12—H12B | 117.9 |
C4—C3—C2 | 128.8 (2) | C11—C12—H12B | 117.9 |
C3—C4—C5 | 117.6 (2) | H12A—C12—H12B | 115.1 |
C3—C4—H4A | 121.2 | C9—C13—C14 | 59.79 (16) |
C5—C4—H4A | 121.2 | C9—C13—H13A | 117.8 |
C6—C5—C4 | 120.8 (2) | C14—C13—H13A | 117.8 |
C6—C5—H5A | 119.6 | C9—C13—H13B | 117.8 |
C4—C5—H5A | 119.6 | C14—C13—H13B | 117.8 |
C5—C6—C7 | 121.7 (2) | H13A—C13—H13B | 114.9 |
C5—C6—H6A | 119.2 | C9—C14—C13 | 59.99 (16) |
C7—C6—H6A | 119.2 | C9—C14—H14A | 117.8 |
C8—C7—C6 | 118.0 (2) | C13—C14—H14A | 117.8 |
C8—C7—H7A | 121.0 | C9—C14—H14B | 117.8 |
C6—C7—H7A | 121.0 | C13—C14—H14B | 117.8 |
C7—C8—C3 | 120.82 (19) | H14A—C14—H14B | 114.9 |
C7—C8—N1 | 129.6 (2) | O2—C15—N1 | 119.9 (2) |
C3—C8—N1 | 109.54 (18) | O2—C15—C16 | 121.4 (2) |
C10—C9—C14 | 128.7 (2) | N1—C15—C16 | 118.7 (2) |
C10—C9—C13 | 130.3 (2) | C15—C16—H16A | 109.5 |
C14—C9—C13 | 60.22 (17) | C15—C16—H16B | 109.5 |
C10—C9—C2 | 86.66 (17) | H16A—C16—H16B | 109.5 |
C14—C9—C2 | 127.7 (2) | C15—C16—H16C | 109.5 |
C13—C9—C2 | 129.1 (2) | H16A—C16—H16C | 109.5 |
O3—C10—C11 | 121.9 (2) | H16B—C16—H16C | 109.5 |
C15—N1—C1—O1 | 1.6 (4) | O3—C2—C9—C10 | 4.84 (16) |
C8—N1—C1—O1 | −179.2 (2) | C3—C2—C9—C10 | 123.6 (2) |
C15—N1—C1—C2 | −176.4 (2) | C1—C2—C9—C10 | −107.4 (2) |
C8—N1—C1—C2 | 2.8 (2) | O3—C2—C9—C14 | −133.6 (3) |
C10—O3—C2—C3 | −131.3 (2) | C3—C2—C9—C14 | −14.8 (4) |
C10—O3—C2—C1 | 113.24 (19) | C1—C2—C9—C14 | 114.2 (3) |
C10—O3—C2—C9 | −5.03 (16) | O3—C2—C9—C13 | 146.8 (2) |
O1—C1—C2—O3 | −59.9 (3) | C3—C2—C9—C13 | −94.4 (3) |
N1—C1—C2—O3 | 118.08 (19) | C1—C2—C9—C13 | 34.6 (3) |
O1—C1—C2—C3 | 177.9 (2) | C2—O3—C10—C11 | −136.0 (3) |
N1—C1—C2—C3 | −4.1 (2) | C2—O3—C10—C12 | 148.7 (2) |
O1—C1—C2—C9 | 40.0 (3) | C2—O3—C10—C9 | 5.16 (17) |
N1—C1—C2—C9 | −142.04 (19) | C14—C9—C10—O3 | 132.7 (2) |
O3—C2—C3—C8 | −115.3 (2) | C13—C9—C10—O3 | −146.1 (2) |
C1—C2—C3—C8 | 4.0 (2) | C2—C9—C10—O3 | −4.96 (16) |
C9—C2—C3—C8 | 138.5 (2) | C14—C9—C10—C11 | −91.1 (3) |
O3—C2—C3—C4 | 62.5 (3) | C13—C9—C10—C11 | −10.0 (4) |
C1—C2—C3—C4 | −178.1 (2) | C2—C9—C10—C11 | 131.2 (3) |
C9—C2—C3—C4 | −43.6 (3) | C14—C9—C10—C12 | −3.9 (4) |
C8—C3—C4—C5 | −0.6 (3) | C13—C9—C10—C12 | 77.3 (4) |
C2—C3—C4—C5 | −178.3 (2) | C2—C9—C10—C12 | −141.5 (3) |
C3—C4—C5—C6 | 1.4 (4) | O3—C10—C11—C12 | −111.1 (3) |
C4—C5—C6—C7 | −0.7 (4) | C9—C10—C11—C12 | 123.5 (3) |
C5—C6—C7—C8 | −0.8 (4) | O3—C10—C12—C11 | 112.7 (3) |
C6—C7—C8—C3 | 1.6 (3) | C9—C10—C12—C11 | −120.4 (3) |
C6—C7—C8—N1 | −178.7 (2) | C10—C9—C13—C14 | −117.4 (3) |
C4—C3—C8—C7 | −0.9 (3) | C2—C9—C13—C14 | 116.3 (3) |
C2—C3—C8—C7 | 177.18 (19) | C10—C9—C14—C13 | 119.8 (3) |
C4—C3—C8—N1 | 179.35 (19) | C2—C9—C14—C13 | −118.4 (3) |
C2—C3—C8—N1 | −2.6 (2) | C1—N1—C15—O2 | 175.8 (2) |
C1—N1—C8—C7 | −179.9 (2) | C8—N1—C15—O2 | −3.2 (3) |
C15—N1—C8—C7 | −0.7 (3) | C1—N1—C15—C16 | −4.7 (3) |
C1—N1—C8—C3 | −0.2 (2) | C8—N1—C15—C16 | 176.3 (2) |
C15—N1—C8—C3 | 179.0 (2) |
Experimental details
Crystal data | |
Chemical formula | C16H15NO3 |
Mr | 269.29 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 10.4584 (1), 9.2661 (2), 13.7923 (3) |
β (°) | 90.329 (1) |
V (Å3) | 1336.57 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.46 × 0.32 × 0.22 |
Data collection | |
Diffractometer | Siemens SMART CCD area-detector diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)'] reflections | 6266, 2346, 1656 |
Rint | 0.116 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.062, 0.176, 0.99 |
No. of reflections | 2346 |
No. of parameters | 183 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.30, −0.40 |
Computer programs: SMART (Siemens, 1996), SAINT (Siemens, 1996), SAINT and SADABS (Sheldrick, 1996), SHELXTL (Sheldrick, 1997), SHELXTL, PARST (Nardelli, 1995) and PLATON (Spek, 1990).
O3—C2 | 1.471 (3) | C2—C9 | 1.533 (3) |
O3—C10 | 1.438 (3) | C9—C10 | 1.494 (3) |
O3—C2—C3 | 114.16 (18) | O3—C10—C11 | 121.9 (2) |
O3—C2—C1 | 110.05 (17) | O3—C10—C12 | 120.8 (2) |
The photoinduced electron transfer (PET) reactions of bicyclopropylidene and its derivatives, so far, have not been thoroughly investigated. In the course of our systematic studies on the PET reactions of various electron-acceptor compounds, we have carried out the photoinduced reactions of bicyclopropylidene with 1-acetylisatin (Wang & Xu, 2002), isolated the title compound, (I), and undertaken its single-crystal X-ray diffraction study.
The bond lengths and angles in (I) (Fig. 1) are within normal ranges (Allen et al., 1987). The geometrical parameters of the indole moiety (C1–C8/N1) are comparable to those of the related structures reported earlier (Usman et al., 2002). Although both atoms C2 and C10 in the oxetane ring (O3/C2/C9/C10) are in the sp3 hybridization state, their different environments cause slight differences in the O3—C2 and O3—C10 bond lengths, and the O3—C2—C1, O3—C2—C3, O3—C10—C11 and O3—C10—C12 angles (Table 1).
The oxetane ring, as is usually observed (Usman et al., 2002), is not exactly planar. The atoms deviate by ±0.033 (2) Å from their mean plane, with the dihedral angle between the C2/O3/C10 and C2/C9/C10 planes being 172.7 (2)°.
The indole moiety is essentially planar, mainly due to the C═O and C—N conjugation, with the dihedral angle between the planes of its heterocyclic and benzene rings being 1.6 (1)°. The acetyl group (O2/C15/C16) bonded to the N1 atom is twisted out of the indole plane by a small angle of 4.8 (1)°, thus indicating that the acetyl group tends to be coplanar with the indole system (Usman et al., 2002), obviously due to the π-conjugation involving the acetyl C═O bond.
The mean plane of the oxetane ring is almost perpendicular to that of the indole moiety, corresponding to dihedral angle of 88.5 (1)°. Similarly, the oxetane ring is also perpendicular with respect to both cyclopropyl rings (C9/C13/C14 and C10/C11/C12), which is not unexpected taking into account the sp3 hybridization state of atoms C2, C9 and C10.
The reference molecule comprising the asymmetric unit and depicted in Fig. 1 shows the S configuration of the chiral center at atom C2. However, the centrosymmetric space group indicates that the crystal is a racemic mixture of both enantiomers of the title compound.