organic compounds
2,2-Difluoro-4-phenyl-1,3,2-dioxaborolo[4,5-c]chromen-5-ium-2-ide
aFaculty of Chemistry, University of Gdańsk, J. Sobieskiego 18, 80-952 Gdańsk, Poland, and bInstitute of Chemistry, V.N. Karazin National University, Svobody 4, 61077 Kharkiv, Ukraine
*Correspondence e-mail: bla@chem.univ.gda.pl
In the crystal, the inversely oriented molecules of the title compound, C15H9BF2O3, form stacks along the a axis via π–π interactions between parallel phenylchromenium fragments. Linked by a network of C—H⋯F interactions, the stacks form layers in the ac plane that are dispersively stabilized in the Two F atoms bonded to the B atom are located in the plane perpendicular to the planar skeleton of the molecule made rigid by two intramolecular C—H⋯O interactions.
Related literature
For general background to 3-hydroxy-2-phenyl-4H-chromene-4-one (flavonol) and its derivatives, see: Kukharenko & Avramenko (2001); Petković et al. (2010); Roshal et al. (1998, 2003); Sytnik et al. (1994). For related structures, see: Belogh-Hergovich et al. (1999); Farina et al. (1995); Kaizer et al. (2007); Okabe et al. (2003). For intermolecular interactions, see: Choudhury & Guru Row (2004); Hunter et al. (2001); Novoa et al. (2006); Thalladi et al. (1998). For the synthesis, see: Roshal et al. (2002).
Experimental
Crystal data
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Refinement
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Data collection: CrysAlis CCD (Oxford Diffraction, 2008); cell CrysAlis RED (Oxford Diffraction, 2008); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009).
Supporting information
https://doi.org/10.1107/S1600536810048919/ng5071sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810048919/ng5071Isup2.hkl
The title compound was obtained during the reaction of 3-hydroxy-2-phenyl-4H-chromene-4-one (flavonol) with BF3 (Roshal et al., 2002). Thus, boron trifluoride dissolved in anhydrous diethyl ether was added dropwise, with continuous stirring, to an equimolar amount of a
of flavonol in anhydrous dichloromethane. After evaporation of the solvents, the residue was recrystallized twice from N,N-dimethylformamide yielding yellow fluorescing crystals suitable for X-Ray investigations (m.p. 485 - 487 K).H atoms were positioned geometrically, with C—H = 0.93 Å, and constrained to ride on their parent atoms with Uiso(H) = 1.2Ueq(C).
3-Hydroxy-2-phenyl-4H-chromene-4-one (flavonol) and its derivatives have been investigated for a long time owing to their unique spectral properties emerging from the
intramolecular proton transfer occurring in them (Sytnik et al., 1994). These compounds turned out to be convenient analytical probes because of their considerable ability to complex various chemical entities (molecules, ions) (Roshal et al., 1998; Roshal et al., 2003; Petković et al., 2010). The latter property was the reason for turning our attention to the possibility of applying of flavonol as an analytical spectral probe for boron compounds (Roshal et al., 2002). As part of these investigations we wanted to see how flavonol behaved in the presence of BF3. Thus we mixed both reagents in dichloromethane, expecting to obtain a molecular complex of flavonol and BF3. The structure of the crystalline product that was actually separated is presented here. It appears that not complexation but condensation of the two reagents, accompanied by the release of HF, takes place (Kukharenko & Avramenko, 2001) and a molecule of a formally zwitterionic canonical structure was produced. Crystal structures of various flavonol complexes have so far been reported (Farina & Yamin, 1995; Belogh-Hergovich et al., 1999; Okabe et al., 2003; Kaizer et al., 2007), but none of them have contained boron.The canonical structure of the title compound suggests that the phenylchromenium core of the molecule is aromatic. This is confirmed by analysis of the bond lengths and angles, as well as comparison of the structure determinated here with the structures of selected compounds containing flavonol units (Farina et al., 1995; Belogh-Hergovich et al., 1999; Okabe et al., 2003; Kaizer et al., 2007). Furthermore, the average deviation from planarity of the phenylchromenium core is 0.0215 (2) and that of the molecule's skeleton is 0.0373 (2). This implies that both the above-mentioned molecular fragments are planar and that two F atoms at the B atom are located in a plane perpendicular to the molecular one (the dihedral angle between the plane of the molecule's skeleton and the plane of B1–F1–F2 is 89.5 (1)°). Furthermore, two intramolecular C–H···O interactions (Table 1, Fig. 1) stiffen the phenylchromenium core, undoubtedly contributing to its planarity.
In the π-π interactions between parallel phenylchromenium fragments (Table 2, Figs. 2 and 3). These stacks are linked by a network of C–H···F interactions arranged in layers in the ac plane (Table 1, Figs. 2 and 3). The above-mentioned layers are dispersively stabilized in the The C–H···O (Novoa et al., 2006) and C–H···F (Thalladi et al.(1998); Choudhury & Guru Row (2004)) interactions are of the hydrogen bond type. Like the π-π contacts, they are of an attractive nature (Hunter et al., 2001).
inversely oriented molecules form stacks along the a axis viaFor general background to 3-hydroxy-2-phenyl-4〈i〉H〈/i〉-chromene-4-one (flavonol) and its derivatives, see: Kukharenko & Avramenko (2001); Petković et al. (2010); Roshal et al. (1998); Roshal et al. (2003); Sytnik et al. (1994). For related structures, see: Belogh-Hergovich et al. (1999); Farina et al. (1995); Kaizer et al. (2007); Okabe et al. (2003). For intermolecular interactions, see: Choudhury & Guru Row (2004); Hunter et al. (2001); Novoa et al. (2006); Thalladi et al. (1998). For the synthesis, see: Roshal et al. (2002).
Data collection: CrysAlis CCD (Oxford Diffraction, 2008); cell
CrysAlis RED (Oxford Diffraction, 2008); data reduction: CrysAlis RED (Oxford Diffraction, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).Fig. 1. The molecular structure of the title compound showing the atom-labeling scheme. Displacement ellipsoids are drawn at the 25% probability level, and H atoms are shown as small spheres of arbitrary radius. Cg1, Cg2 and Cg3 denote the ring centroids. The C–H···O hydrogen bonds are represented by dashed lines. | |
Fig. 2. The arrangement of the molecules in the crystal structure. The C–H···O and C–H···F interactions are represented by dashed lines, the π–π contacts by dotted lines. H atoms not involved in interactions have been omitted. [Symmetry codes: (i) –x + 1, –y, –z; (ii) –x + 1, –y, –z + 1; (iii) –x, –y, –z + 1.] | |
Fig. 3. Molecular stacks in the crystal structure, viewed along the a axis. The C–H···F interactions are represented by dashed lines. H atoms not involved in interactions have been omitted. |
C15H9BF2O3 | Z = 2 |
Mr = 286.03 | F(000) = 292 |
Triclinic, P1 | Dx = 1.514 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.1969 (10) Å | Cell parameters from 2218 reflections |
b = 9.7054 (11) Å | θ = 3.0–25.1° |
c = 9.9986 (15) Å | µ = 0.12 mm−1 |
α = 74.310 (11)° | T = 295 K |
β = 75.931 (13)° | Needle, yellow |
γ = 71.296 (11)° | 0.6 × 0.02 × 0.02 mm |
V = 627.43 (15) Å3 |
Oxford Diffraction Gemini R Ultra Ruby CCD diffractometer | 2218 independent reflections |
Radiation source: Enhance (Mo) X-ray Source | 996 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.034 |
Detector resolution: 10.4002 pixels mm-1 | θmax = 25.1°, θmin = 3.0° |
ω scans | h = −8→8 |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008) | k = −10→11 |
Tmin = 0.945, Tmax = 0.979 | l = −9→11 |
4848 measured reflections |
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)] = 0.058 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.234 | H-atom parameters constrained |
S = 1.10 | w = 1/[σ2(Fo2) + (0.0787P)2 + 0.4107P] where P = (Fo2 + 2Fc2)/3 |
2218 reflections | (Δ/σ)max < 0.001 |
190 parameters | Δρmax = 0.22 e Å−3 |
0 restraints | Δρmin = −0.24 e Å−3 |
C15H9BF2O3 | γ = 71.296 (11)° |
Mr = 286.03 | V = 627.43 (15) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.1969 (10) Å | Mo Kα radiation |
b = 9.7054 (11) Å | µ = 0.12 mm−1 |
c = 9.9986 (15) Å | T = 295 K |
α = 74.310 (11)° | 0.6 × 0.02 × 0.02 mm |
β = 75.931 (13)° |
Oxford Diffraction Gemini R Ultra Ruby CCD diffractometer | 2218 independent reflections |
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2008) | 996 reflections with I > 2σ(I) |
Tmin = 0.945, Tmax = 0.979 | Rint = 0.034 |
4848 measured reflections |
R[F2 > 2σ(F2)] = 0.058 | 0 restraints |
wR(F2) = 0.234 | H-atom parameters constrained |
S = 1.10 | Δρmax = 0.22 e Å−3 |
2218 reflections | Δρmin = −0.24 e Å−3 |
190 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 | ||
B1 | 0.4867 (13) | −0.1835 (7) | 0.2184 (8) | 0.075 (2) | |
O1 | 0.3873 (5) | −0.2005 (3) | 0.3680 (3) | 0.0605 (10) | |
C1 | 0.1714 (6) | −0.1185 (5) | 0.6585 (5) | 0.0395 (11) | |
F1 | 0.3869 (6) | −0.2186 (4) | 0.1401 (3) | 0.1025 (14) | |
O2 | 0.4773 (5) | −0.0183 (3) | 0.1743 (3) | 0.0594 (10) | |
C2 | 0.0722 (8) | −0.0564 (6) | 0.7748 (5) | 0.0600 (15) | |
H2 | 0.0499 | 0.0447 | 0.7694 | 0.072* | |
F2 | 0.6830 (6) | −0.2651 (4) | 0.2068 (4) | 0.1059 (14) | |
O3 | 0.2079 (5) | 0.1167 (3) | 0.5341 (3) | 0.0480 (9) | |
C3 | 0.0071 (9) | −0.1459 (6) | 0.8983 (6) | 0.0680 (16) | |
H3 | −0.0595 | −0.1045 | 0.9764 | 0.082* | |
C4 | 0.0389 (8) | −0.2934 (6) | 0.9077 (6) | 0.0628 (15) | |
H4 | −0.0061 | −0.3521 | 0.9919 | 0.075* | |
C5 | 0.1364 (8) | −0.3559 (6) | 0.7946 (6) | 0.0601 (15) | |
H5 | 0.1595 | −0.4574 | 0.8022 | 0.072* | |
C6 | 0.2010 (7) | −0.2690 (5) | 0.6686 (6) | 0.0535 (13) | |
H6 | 0.2643 | −0.3114 | 0.5907 | 0.064* | |
C7 | 0.2432 (6) | −0.0265 (5) | 0.5263 (5) | 0.0408 (11) | |
C8 | 0.3379 (7) | −0.0667 (5) | 0.3996 (5) | 0.0436 (12) | |
C9 | 0.3902 (7) | 0.0404 (5) | 0.2829 (5) | 0.0453 (12) | |
C10 | 0.3501 (7) | 0.1903 (5) | 0.2890 (5) | 0.0414 (11) | |
C11 | 0.3933 (7) | 0.3038 (5) | 0.1770 (5) | 0.0549 (14) | |
H11 | 0.4525 | 0.2835 | 0.0882 | 0.066* | |
C12 | 0.3484 (8) | 0.4446 (6) | 0.1983 (6) | 0.0587 (14) | |
H12 | 0.3739 | 0.5212 | 0.1237 | 0.070* | |
C13 | 0.2639 (8) | 0.4731 (5) | 0.3325 (6) | 0.0601 (15) | |
H13 | 0.2371 | 0.5689 | 0.3466 | 0.072* | |
C14 | 0.2191 (7) | 0.3639 (5) | 0.4443 (6) | 0.0566 (14) | |
H14 | 0.1636 | 0.3844 | 0.5334 | 0.068* | |
C15 | 0.2586 (7) | 0.2227 (5) | 0.4210 (5) | 0.0454 (12) |
U11 | U22 | U33 | U12 | U13 | U23 | |
B1 | 0.113 (6) | 0.055 (4) | 0.059 (5) | −0.037 (4) | 0.023 (4) | −0.031 (4) |
O1 | 0.090 (3) | 0.0377 (19) | 0.050 (2) | −0.0213 (18) | 0.0070 (19) | −0.0153 (16) |
C1 | 0.037 (3) | 0.042 (3) | 0.039 (3) | −0.013 (2) | −0.005 (2) | −0.007 (2) |
F1 | 0.189 (4) | 0.081 (2) | 0.059 (2) | −0.073 (3) | 0.000 (2) | −0.0260 (19) |
O2 | 0.086 (3) | 0.047 (2) | 0.041 (2) | −0.0228 (18) | 0.0087 (19) | −0.0157 (17) |
C2 | 0.076 (4) | 0.058 (3) | 0.048 (3) | −0.026 (3) | 0.003 (3) | −0.016 (3) |
F2 | 0.122 (3) | 0.062 (2) | 0.092 (3) | −0.004 (2) | 0.040 (2) | −0.025 (2) |
O3 | 0.059 (2) | 0.0383 (18) | 0.043 (2) | −0.0122 (15) | 0.0004 (16) | −0.0117 (16) |
C3 | 0.093 (4) | 0.076 (4) | 0.037 (3) | −0.036 (3) | 0.005 (3) | −0.014 (3) |
C4 | 0.066 (4) | 0.073 (4) | 0.043 (3) | −0.032 (3) | −0.001 (3) | 0.007 (3) |
C5 | 0.058 (3) | 0.054 (3) | 0.055 (4) | −0.013 (3) | −0.004 (3) | 0.003 (3) |
C6 | 0.056 (3) | 0.049 (3) | 0.054 (3) | −0.016 (3) | −0.002 (3) | −0.012 (3) |
C7 | 0.041 (3) | 0.040 (3) | 0.041 (3) | −0.009 (2) | −0.006 (2) | −0.010 (2) |
C8 | 0.044 (3) | 0.043 (3) | 0.039 (3) | −0.009 (2) | −0.004 (2) | −0.008 (2) |
C9 | 0.047 (3) | 0.047 (3) | 0.041 (3) | −0.014 (2) | 0.000 (2) | −0.014 (2) |
C10 | 0.045 (3) | 0.038 (3) | 0.043 (3) | −0.012 (2) | −0.005 (2) | −0.011 (2) |
C11 | 0.065 (4) | 0.050 (3) | 0.049 (3) | −0.022 (3) | 0.001 (3) | −0.011 (3) |
C12 | 0.066 (4) | 0.047 (3) | 0.056 (4) | −0.021 (3) | −0.001 (3) | −0.001 (3) |
C13 | 0.071 (4) | 0.038 (3) | 0.066 (4) | −0.010 (3) | −0.001 (3) | −0.018 (3) |
C14 | 0.062 (3) | 0.042 (3) | 0.061 (4) | −0.011 (3) | 0.001 (3) | −0.018 (3) |
C15 | 0.046 (3) | 0.039 (3) | 0.046 (3) | −0.012 (2) | −0.002 (2) | −0.006 (2) |
B1—F1 | 1.349 (8) | C5—C6 | 1.381 (7) |
B1—F2 | 1.375 (9) | C5—H5 | 0.9300 |
B1—O1 | 1.483 (7) | C6—H6 | 0.9300 |
B1—O2 | 1.527 (7) | C7—C8 | 1.377 (6) |
O1—C8 | 1.336 (5) | C8—C9 | 1.402 (6) |
C1—C6 | 1.386 (6) | C9—C10 | 1.405 (6) |
C1—C2 | 1.387 (6) | C10—C11 | 1.396 (6) |
C1—C7 | 1.462 (6) | C10—C15 | 1.395 (6) |
O2—C9 | 1.293 (5) | C11—C12 | 1.363 (7) |
C2—C3 | 1.378 (7) | C11—H11 | 0.9300 |
C2—H2 | 0.9300 | C12—C13 | 1.394 (7) |
O3—C7 | 1.351 (5) | C12—H12 | 0.9300 |
O3—C15 | 1.371 (5) | C13—C14 | 1.371 (7) |
C3—C4 | 1.356 (7) | C13—H13 | 0.9300 |
C3—H3 | 0.9300 | C14—C15 | 1.380 (6) |
C4—C5 | 1.360 (7) | C14—H14 | 0.9300 |
C4—H4 | 0.9300 | ||
F1—B1—F2 | 112.0 (5) | O3—C7—C8 | 117.9 (4) |
F1—B1—O1 | 110.8 (5) | O3—C7—C1 | 113.2 (4) |
F2—B1—O1 | 110.9 (6) | C8—C7—C1 | 128.9 (4) |
F1—B1—O2 | 110.6 (6) | O1—C8—C7 | 128.2 (4) |
F2—B1—O2 | 108.8 (5) | O1—C8—C9 | 111.7 (4) |
O1—B1—O2 | 103.3 (4) | C7—C8—C9 | 120.1 (4) |
C8—O1—B1 | 106.4 (4) | O2—C9—C8 | 111.0 (4) |
C6—C1—C2 | 119.3 (4) | O2—C9—C10 | 126.5 (4) |
C6—C1—C7 | 120.2 (4) | C8—C9—C10 | 122.5 (4) |
C2—C1—C7 | 120.6 (4) | C11—C10—C15 | 119.6 (4) |
C9—O2—B1 | 107.5 (4) | C11—C10—C9 | 125.9 (5) |
C3—C2—C1 | 119.3 (5) | C15—C10—C9 | 114.6 (4) |
C3—C2—H2 | 120.3 | C12—C11—C10 | 119.7 (5) |
C1—C2—H2 | 120.3 | C12—C11—H11 | 120.2 |
C7—O3—C15 | 122.7 (4) | C10—C11—H11 | 120.2 |
C4—C3—C2 | 120.9 (5) | C11—C12—C13 | 119.7 (5) |
C4—C3—H3 | 119.5 | C11—C12—H12 | 120.1 |
C2—C3—H3 | 119.5 | C13—C12—H12 | 120.1 |
C3—C4—C5 | 120.3 (5) | C14—C13—C12 | 121.9 (5) |
C3—C4—H4 | 119.8 | C14—C13—H13 | 119.1 |
C5—C4—H4 | 119.8 | C12—C13—H13 | 119.1 |
C4—C5—C6 | 120.2 (5) | C13—C14—C15 | 118.2 (5) |
C4—C5—H5 | 119.9 | C13—C14—H14 | 120.9 |
C6—C5—H5 | 119.9 | C15—C14—H14 | 120.9 |
C1—C6—C5 | 119.9 (5) | O3—C15—C14 | 116.8 (4) |
C1—C6—H6 | 120.1 | O3—C15—C10 | 122.2 (4) |
C5—C6—H6 | 120.1 | C14—C15—C10 | 120.9 (4) |
F1—B1—O1—C8 | −119.9 (5) | C1—C7—C8—C9 | 178.1 (4) |
F2—B1—O1—C8 | 114.9 (4) | B1—O2—C9—C8 | 0.3 (6) |
O2—B1—O1—C8 | −1.5 (7) | B1—O2—C9—C10 | −179.8 (5) |
F1—B1—O2—C9 | 119.3 (5) | O1—C8—C9—O2 | −1.4 (6) |
F2—B1—O2—C9 | −117.2 (5) | C7—C8—C9—O2 | −180.0 (4) |
O1—B1—O2—C9 | 0.7 (7) | O1—C8—C9—C10 | 178.7 (4) |
C6—C1—C2—C3 | 0.7 (7) | C7—C8—C9—C10 | 0.2 (7) |
C7—C1—C2—C3 | −179.7 (5) | O2—C9—C10—C11 | 1.6 (8) |
C1—C2—C3—C4 | 0.1 (8) | C8—C9—C10—C11 | −178.5 (5) |
C2—C3—C4—C5 | 0.1 (8) | O2—C9—C10—C15 | −178.4 (5) |
C3—C4—C5—C6 | −1.0 (8) | C8—C9—C10—C15 | 1.4 (6) |
C2—C1—C6—C5 | −1.6 (7) | C15—C10—C11—C12 | 0.9 (7) |
C7—C1—C6—C5 | 178.7 (4) | C9—C10—C11—C12 | −179.1 (5) |
C4—C5—C6—C1 | 1.8 (7) | C10—C11—C12—C13 | 1.5 (8) |
C15—O3—C7—C8 | 1.5 (6) | C11—C12—C13—C14 | −1.8 (8) |
C15—O3—C7—C1 | −178.3 (4) | C12—C13—C14—C15 | −0.5 (8) |
C6—C1—C7—O3 | −178.3 (4) | C7—O3—C15—C14 | −178.3 (4) |
C2—C1—C7—O3 | 2.1 (6) | C7—O3—C15—C10 | 0.2 (7) |
C6—C1—C7—C8 | 1.9 (7) | C13—C14—C15—O3 | −178.5 (4) |
C2—C1—C7—C8 | −177.7 (5) | C13—C14—C15—C10 | 2.9 (7) |
B1—O1—C8—C7 | −179.8 (6) | C11—C10—C15—O3 | 178.3 (4) |
B1—O1—C8—C9 | 1.8 (6) | C9—C10—C15—O3 | −1.6 (7) |
O3—C7—C8—O1 | −179.9 (4) | C11—C10—C15—C14 | −3.2 (7) |
C1—C7—C8—O1 | −0.2 (8) | C9—C10—C15—C14 | 176.8 (4) |
O3—C7—C8—C9 | −1.6 (6) |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2···O3 | 0.93 | 2.37 | 2.700 (6) | 100 |
C6—H6···O1 | 0.93 | 2.29 | 2.967 (6) | 129 |
C11—H11···F1i | 0.93 | 2.44 | 3.373 (6) | 177 |
Symmetry code: (i) −x+1, −y, −z. |
Experimental details
Crystal data | |
Chemical formula | C15H9BF2O3 |
Mr | 286.03 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 295 |
a, b, c (Å) | 7.1969 (10), 9.7054 (11), 9.9986 (15) |
α, β, γ (°) | 74.310 (11), 75.931 (13), 71.296 (11) |
V (Å3) | 627.43 (15) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.6 × 0.02 × 0.02 |
Data collection | |
Diffractometer | Oxford Diffraction Gemini R Ultra Ruby CCD |
Absorption correction | Multi-scan (CrysAlis RED; Oxford Diffraction, 2008) |
Tmin, Tmax | 0.945, 0.979 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4848, 2218, 996 |
Rint | 0.034 |
(sin θ/λ)max (Å−1) | 0.596 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.058, 0.234, 1.10 |
No. of reflections | 2218 |
No. of parameters | 190 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.22, −0.24 |
Computer programs: CrysAlis CCD (Oxford Diffraction, 2008), CrysAlis RED (Oxford Diffraction, 2008), SHELXS97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2···O3 | 0.93 | 2.37 | 2.700 (6) | 100 |
C6—H6···O1 | 0.93 | 2.29 | 2.967 (6) | 129 |
C11—H11···F1i | 0.93 | 2.44 | 3.373 (6) | 177 |
Symmetry code: (i) −x+1, −y, −z. |
Cg1, Cg2 and Cg3 are the centroids of the O3/C7–C10/C15, C10–C15 and C1–C6 rings, respectively. CgI···CgJ is the distance between ring centroids. The dihedral angle is that between the planes of the rings I and J. CgI_Perp is the perpendicuar distance of CgI from ring J. CgI_Offset is the distance between CgI and the perpendicular projection of CgJ on ring I. |
I | J | CgI···CgJ | Dihedral angle | CgI_Perp | CgI_Offset |
1 | 1ii | 3.512 (3) | 0 | 3.344 (2) | 1.076 (2) |
1 | 3iii | 3.572 (3) | 2.3 (3) | 3.450 (2) | 0.956 (2) |
2 | 3ii | 3.970 (3) | 4.3 (3) | 3.342 (2) | 2.143 (2) |
2 | 3iii | 3.925 (3) | 4.3 (3) | 3.472 (2) | 1.831 (2) |
3 | 1iii | 3.571 (3) | 2.3 (3) | 3.428 (2) | 1.000 (2) |
3 | 2ii | 3.970 (3) | 4.3 (3) | 3.492 (2) | 1.889 (2) |
3 | 2iii | 3.925 (3) | 4.3 (3) | 3.404 (2) | 1.954 (2) |
Symmetry codes: (ii) -x + 1, -y, -z + 1; (iii) -x, -y, -z + 1. |
Acknowledgements
This study was financed by the State Funds for Scientific Research (grant DS/8220–4–0087–0).
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3-Hydroxy-2-phenyl-4H-chromene-4-one (flavonol) and its derivatives have been investigated for a long time owing to their unique spectral properties emerging from the excited state intramolecular proton transfer occurring in them (Sytnik et al., 1994). These compounds turned out to be convenient analytical probes because of their considerable ability to complex various chemical entities (molecules, ions) (Roshal et al., 1998; Roshal et al., 2003; Petković et al., 2010). The latter property was the reason for turning our attention to the possibility of applying of flavonol as an analytical spectral probe for boron compounds (Roshal et al., 2002). As part of these investigations we wanted to see how flavonol behaved in the presence of BF3. Thus we mixed both reagents in dichloromethane, expecting to obtain a molecular complex of flavonol and BF3. The structure of the crystalline product that was actually separated is presented here. It appears that not complexation but condensation of the two reagents, accompanied by the release of HF, takes place (Kukharenko & Avramenko, 2001) and a molecule of a formally zwitterionic canonical structure was produced. Crystal structures of various flavonol complexes have so far been reported (Farina & Yamin, 1995; Belogh-Hergovich et al., 1999; Okabe et al., 2003; Kaizer et al., 2007), but none of them have contained boron.
The canonical structure of the title compound suggests that the phenylchromenium core of the molecule is aromatic. This is confirmed by analysis of the bond lengths and angles, as well as comparison of the structure determinated here with the structures of selected compounds containing flavonol units (Farina et al., 1995; Belogh-Hergovich et al., 1999; Okabe et al., 2003; Kaizer et al., 2007). Furthermore, the average deviation from planarity of the phenylchromenium core is 0.0215 (2) and that of the molecule's skeleton is 0.0373 (2). This implies that both the above-mentioned molecular fragments are planar and that two F atoms at the B atom are located in a plane perpendicular to the molecular one (the dihedral angle between the plane of the molecule's skeleton and the plane of B1–F1–F2 is 89.5 (1)°). Furthermore, two intramolecular C–H···O interactions (Table 1, Fig. 1) stiffen the phenylchromenium core, undoubtedly contributing to its planarity.
In the crystal structure, inversely oriented molecules form stacks along the a axis via π-π interactions between parallel phenylchromenium fragments (Table 2, Figs. 2 and 3). These stacks are linked by a network of C–H···F interactions arranged in layers in the ac plane (Table 1, Figs. 2 and 3). The above-mentioned layers are dispersively stabilized in the crystal lattice. The C–H···O (Novoa et al., 2006) and C–H···F (Thalladi et al.(1998); Choudhury & Guru Row (2004)) interactions are of the hydrogen bond type. Like the π-π contacts, they are of an attractive nature (Hunter et al., 2001).