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Molecules of the title compound, (E)-2-(2-phenyl­ethenyl)-1,3,2-benzodioxaborole, C14H11BO2, are essentially completely planar with a high degree of conjugation. They pack with a herring-bone pattern in the crystal structure. The compound is synthesized with high regioselectivity by hydro­boration of phenyl­acetyl­ene with catecholborane.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536800019097/na6019sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536800019097/na6019Isup2.hkl
Contains datablock I

CCDC reference: 155891

Key indicators

  • Single-crystal X-ray study
  • T = 160 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.037
  • wR factor = 0.095
  • Data-to-parameter ratio = 16.6

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Yellow Alert 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 = 0.086 Value of mu given = 0.090 REFLT_03 From the CIF: _diffrn_reflns_theta_max 28.60 From the CIF: _reflns_number_total 2571 TEST2: Reflns within _diffrn_reflns_theta_max Count of symmetry unique reflns 2849 Completeness (_total/calc) 90.24% Alert C: < 95% complete
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
2 Alert Level C = Please check

Comment top

Alkenylboronic esters and acids are versatile synthetic intermediates (Lane & Kabalka, 1976) for products such as cis-alkenes and haloalkenes, and they have important applications in palladium-catalysed cross-coupling reactions and the formation of organometallic compounds (Suzuki, 1985, 1998; Ohe et al., 1988; Larock et al., 1972; Pappo & Collins, 1972). The title compound, (I), was obtained by a hydroboration reaction of phenylacetylene with catecholborane (Brown & Gupta, 1972, 1975; Brown & Chandrasekharan, 1983). The first reported preparation of this compound (Joy et al., 1966) involved treatment of cyclooctatetraene with boron trichloride, followed by reaction of the resulting (E)-styrylboron dichloride with catechol. In order to study the influence of electron-donating and electron-withdrawing substituents at the para-position of the phenyl ring on the reactivity of the double bond in catalysed hydroborations of styrylboronate esters, a series of para-substituted analogues has been prepared (Wiesauer, 1997).

The molecule (Fig. 1) is essentially completely planar, with an r.m.s. deviation of 0.071 Å from the least-squares plane through all atoms. All torsion angles are close to 0 and 180°, the largest corresponding to a twist of about 6° about the C2—C21 bond linking the phenyl group to the central alkene unit. Bond lengths and angles are normal, with B—C somewhat shorter and CC longer than generally observed for single and double bonds, respectively (Allen et al., 1992); together with the planarity of the molecule, they indicate extensive delocalization.

It is instructive to compare the title compound with two closely related styryl bis(boronate) esters, (Z)-[(4-NC—C6H4)-C(Bcat)CH(Bcat)] [(II); Bcat is 1,3,2-benzodioxaborole; cat = 1,2-O2C6H4; Clegg et al., 1996] and (Z)-[(4-MeO-C6H4)-C(Bcat)CH(BCat)] [(III); Lesley et al., 1996]. These differ from (I) in having either a π-acceptor or π-donor substituent at the para-position of the phenyl ring attached to the α-carbon of the alkene and also a second Bcat moiety at Cα. In (II) and (III), the Bcat at the β-position is approximately coplanar (dihedral angles approximately 9 and 7°, respectively) with the alkene unit, as in (I), whereas the Bcat groups at Cα in (II) and (III) are roughly perpendicular (80 and 84°, respectively) to the alkene plane. In both (II) and (III), the Cβ—B distances [1.535 (2) and 1.526 (2) Å] are significantly shorter than their Cα—B distances [1.569 (2) and 1.566 (2) Å] and are consistent with the Cβ—B distance in (I) of 1.5321 (17) Å. Presumably this is a reflection of the delocalization present when the Bcat group is coplanar with the alkene and trans to the aryl moiety. The CC distance in (I) [1.3368 (16) Å] is shorter than the corresponding distance in either (II) or (III) [1.349 (2) and 1.348 (2) Å, respectively] and is probably a result of less steric repulsion in the less substituted alkene.

This structure was recently used as a test of crystal structure prediction methods (Lommerse et al., 2000), and proved to be a considerable challenge to the currently available software systems, with only one prediction reasonably close to the experimentally observed structure.

Experimental top

In a nitrogen-filled glove-box, phenylacetylene (4.0 g, 39 mmol) and catecholborane (4.7 g, 39 mmol) were heated at 343 K for 2 h in a scintillation vial. On cooling, an orange solid was formed. The pure product was obtained as a colourless crystalline material by recrystallization from diethylether/hexane by solvent diffusion at 238 K, in 70% yield. Analysis calculated: C 75.73, H 4.99%; found: C 75.30, H 4.98%. 1H NMR (200 MHz): δ 6.48 (d, J = 18.5 Hz, 1H, PhCH), 7.08 (m, 2H, C6H4), 7.26 (m, 2H, C6H4), 7.38 (m, 3H, C6H5), 7.58 (m, 2H, C6H5), 7.77 (d, J = 18.5 Hz, 1H, BCH). 13C{1H} NMR (50 MHz): δ 112.3 (2 C, C3 and C6 of C6H4), 122.6 (2 C, C4 and C5 of C6H4), 127.4 (2 C, Ph), 128.7 (2 C, Ph), 129.6 (1 C, C4 of Ph), 136.9 (1 C, C1 of Ph), 148.3 (2 C, C1 and C2 of C6H4), 152.0 (1 C, PhCH), resonances of C bonded to B too broad to be observed. 11B{1H} NMR (64 MHz): δ 31.3. MS: 222 (M+, 100%), 207 (26%), 196 (52%), 179 (30%), 178 (30%), 144 (68%), 136 (78%), 129 (21%), 120 (84%), 111 (60%), 110 (79%), 102 (77%), 92 (48%).

Refinement top

The data collection nominally covered over a hemisphere of reciprocal space, by a combination of three sets of exposures; each set had a different ϕ angle for the crystal and each exposure covered 0.3° in ω. H atoms were placed geometrically and refined with a riding model (including free rotation about C—C bonds), and with Uiso constrained to be 1.2Ueq of the carrier atom.

Computing details top

Data collection: SMART (Siemens, 1995); cell refinement: local programs; data reduction: SAINT (Siemens, 1995); program(s) used to solve structure: SHELXTL (Sheldrick, 1994); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and local programs.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I) with atom labels and 50% probability ellipsoids for non-H atoms.
(E)-2-(2-phenylethenyl)-1,3,2-benzodioxaborole top
Crystal data top
C14H11BO2F(000) = 464
Mr = 222.04Dx = 1.328 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 6.8351 (9) ÅCell parameters from 5221 reflections
b = 7.6342 (10) Åθ = 2.8–28.6°
c = 21.422 (3) ŵ = 0.09 mm1
β = 96.447 (3)°T = 160 K
V = 1110.8 (3) Å3Block, colourless
Z = 40.62 × 0.50 × 0.40 mm
Data collection top
Bruker SMART 1K CCD
diffractometer
2326 reflections with I > 2σ(I)
Radiation source: sealed tubeRint = 0.022
Graphite monochromatorθmax = 28.6°, θmin = 1.9°
Detector resolution: 8.192 pixels mm-1h = 98
ω rotation with narrow frames scansk = 610
6709 measured reflectionsl = 2828
2571 independent reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.037H-atom parameters constrained
wR(F2) = 0.095 w = 1/[σ2(Fo2) + (0.0389P)2 + 0.3966P]
where P = (Fo2 + 2Fc2)/3
S = 1.06(Δ/σ)max = 0.001
2571 reflectionsΔρmax = 0.26 e Å3
155 parametersΔρmin = 0.15 e Å3
0 restraintsExtinction correction: SHELXTL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.021 (2)
Crystal data top
C14H11BO2V = 1110.8 (3) Å3
Mr = 222.04Z = 4
Monoclinic, P21/cMo Kα radiation
a = 6.8351 (9) ŵ = 0.09 mm1
b = 7.6342 (10) ÅT = 160 K
c = 21.422 (3) Å0.62 × 0.50 × 0.40 mm
β = 96.447 (3)°
Data collection top
Bruker SMART 1K CCD
diffractometer
2326 reflections with I > 2σ(I)
6709 measured reflectionsRint = 0.022
2571 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0370 restraints
wR(F2) = 0.095H-atom parameters constrained
S = 1.06Δρmax = 0.26 e Å3
2571 reflectionsΔρmin = 0.15 e Å3
155 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.28827 (17)0.60351 (16)0.42739 (5)0.0297 (3)
H10.19410.53900.40060.036*
C20.47581 (16)0.59715 (14)0.41531 (5)0.0259 (2)
H20.56850.66060.44300.031*
B10.21424 (19)0.70732 (17)0.48127 (6)0.0273 (3)
O10.33111 (11)0.80614 (10)0.52550 (4)0.0274 (2)
O20.01719 (12)0.71233 (11)0.49180 (4)0.0284 (2)
C110.20129 (15)0.87370 (14)0.56460 (5)0.0242 (2)
C120.01226 (16)0.81736 (14)0.54409 (5)0.0244 (2)
C130.14856 (16)0.86350 (15)0.57367 (5)0.0284 (2)
H130.27780.82530.55900.034*
C140.11031 (18)0.96985 (15)0.62656 (5)0.0303 (3)
H140.21631.00450.64890.036*
C150.07932 (18)1.02632 (15)0.64730 (5)0.0308 (3)
H150.09981.09830.68360.037*
C160.24022 (17)0.98000 (15)0.61615 (5)0.0290 (2)
H160.36961.01980.62990.035*
C210.55373 (15)0.50245 (14)0.36375 (5)0.0232 (2)
C220.75132 (16)0.52442 (15)0.35424 (5)0.0273 (2)
H220.83360.59750.38180.033*
C230.82871 (17)0.44080 (16)0.30499 (5)0.0310 (3)
H230.96250.45890.29860.037*
C240.71196 (18)0.33125 (16)0.26518 (5)0.0303 (3)
H240.76540.27340.23170.036*
C250.51591 (17)0.30617 (15)0.27446 (5)0.0295 (3)
H250.43540.23060.24730.035*
C260.43755 (16)0.39075 (15)0.32302 (5)0.0266 (2)
H260.30320.37290.32880.032*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0290 (6)0.0314 (6)0.0286 (6)0.0024 (4)0.0026 (4)0.0029 (5)
C20.0299 (5)0.0247 (5)0.0229 (5)0.0012 (4)0.0017 (4)0.0011 (4)
B10.0278 (6)0.0272 (6)0.0270 (6)0.0034 (5)0.0034 (5)0.0025 (5)
O10.0242 (4)0.0310 (4)0.0275 (4)0.0029 (3)0.0045 (3)0.0003 (3)
O20.0267 (4)0.0309 (4)0.0279 (4)0.0006 (3)0.0042 (3)0.0055 (3)
C110.0245 (5)0.0236 (5)0.0249 (5)0.0032 (4)0.0047 (4)0.0047 (4)
C120.0289 (5)0.0217 (5)0.0226 (5)0.0013 (4)0.0027 (4)0.0012 (4)
C130.0251 (5)0.0293 (6)0.0312 (6)0.0006 (4)0.0051 (4)0.0012 (5)
C140.0334 (6)0.0283 (6)0.0309 (6)0.0042 (5)0.0105 (5)0.0012 (5)
C150.0396 (6)0.0273 (5)0.0256 (5)0.0003 (5)0.0045 (4)0.0016 (4)
C160.0298 (6)0.0282 (6)0.0283 (5)0.0018 (4)0.0000 (4)0.0013 (4)
C210.0244 (5)0.0230 (5)0.0220 (5)0.0029 (4)0.0023 (4)0.0040 (4)
C220.0248 (5)0.0288 (5)0.0276 (5)0.0003 (4)0.0006 (4)0.0018 (4)
C230.0248 (5)0.0362 (6)0.0330 (6)0.0026 (5)0.0077 (4)0.0044 (5)
C240.0368 (6)0.0293 (6)0.0259 (5)0.0059 (5)0.0087 (4)0.0016 (4)
C250.0338 (6)0.0273 (6)0.0270 (5)0.0003 (4)0.0010 (4)0.0017 (4)
C260.0240 (5)0.0275 (5)0.0284 (5)0.0009 (4)0.0031 (4)0.0002 (4)
Geometric parameters (Å, º) top
C1—C21.3368 (16)C14—H140.950
C1—B11.5321 (17)C15—C161.3945 (17)
C1—H10.950C15—H150.950
C2—C211.4692 (15)C16—H160.950
C2—H20.950C21—C221.3983 (15)
B1—O21.3909 (15)C21—C261.4013 (15)
B1—O11.3910 (15)C22—C231.3877 (16)
O1—C111.3864 (13)C22—H220.950
O2—C121.3811 (13)C23—C241.3823 (17)
C11—C161.3722 (16)C23—H230.950
C11—C121.3856 (15)C24—C251.3898 (16)
C12—C131.3749 (15)C24—H240.950
C13—C141.3944 (16)C25—C261.3824 (16)
C13—H130.950C25—H250.950
C14—C151.3907 (17)C26—H260.950
C2—C1—B1124.72 (11)C14—C15—H15119.2
C2—C1—H1117.6C16—C15—H15119.2
B1—C1—H1117.6C11—C16—C15116.29 (11)
C1—C2—C21126.86 (11)C11—C16—H16121.9
C1—C2—H2116.6C15—C16—H16121.9
C21—C2—H2116.6C22—C21—C26118.12 (10)
O2—B1—O1111.54 (10)C22—C21—C2119.22 (10)
O2—B1—C1122.96 (11)C26—C21—C2122.66 (10)
O1—B1—C1125.50 (11)C23—C22—C21120.83 (11)
C11—O1—B1104.82 (9)C23—C22—H22119.6
C12—O2—B1105.06 (9)C21—C22—H22119.6
C16—C11—C12121.90 (10)C24—C23—C22120.29 (10)
C16—C11—O1128.82 (10)C24—C23—H23119.9
C12—C11—O1109.28 (9)C22—C23—H23119.9
C13—C12—O2128.04 (10)C23—C24—C25119.63 (10)
C13—C12—C11122.66 (10)C23—C24—H24120.2
O2—C12—C11109.30 (9)C25—C24—H24120.2
C12—C13—C14115.91 (11)C26—C25—C24120.29 (11)
C12—C13—H13122.0C26—C25—H25119.9
C14—C13—H13122.0C24—C25—H25119.9
C15—C14—C13121.54 (11)C25—C26—C21120.83 (10)
C15—C14—H14119.2C25—C26—H26119.6
C13—C14—H14119.2C21—C26—H26119.6
C14—C15—C16121.69 (11)
B1—C1—C2—C21178.83 (11)C11—C12—C13—C140.71 (17)
C2—C1—B1—O2179.17 (11)C12—C13—C14—C150.58 (17)
C2—C1—B1—O11.22 (19)C13—C14—C15—C160.25 (18)
O2—B1—O1—C110.16 (12)C12—C11—C16—C150.84 (17)
C1—B1—O1—C11179.49 (11)O1—C11—C16—C15179.21 (10)
O1—B1—O2—C120.00 (12)C14—C15—C16—C110.96 (17)
C1—B1—O2—C12179.65 (10)C1—C2—C21—C22173.52 (11)
B1—O1—C11—C16179.80 (11)C1—C2—C21—C266.08 (18)
B1—O1—C11—C120.25 (12)C26—C21—C22—C231.36 (16)
B1—O2—C12—C13179.91 (11)C2—C21—C22—C23178.25 (10)
B1—O2—C12—C110.16 (12)C21—C22—C23—C241.30 (17)
C16—C11—C12—C130.01 (17)C22—C23—C24—C250.46 (18)
O1—C11—C12—C13179.97 (10)C23—C24—C25—C260.28 (17)
C16—C11—C12—O2179.78 (10)C24—C25—C26—C210.20 (17)
O1—C11—C12—O20.26 (12)C22—C21—C26—C250.62 (16)
O2—C12—C13—C14179.02 (10)C2—C21—C26—C25178.99 (10)

Experimental details

Crystal data
Chemical formulaC14H11BO2
Mr222.04
Crystal system, space groupMonoclinic, P21/c
Temperature (K)160
a, b, c (Å)6.8351 (9), 7.6342 (10), 21.422 (3)
β (°) 96.447 (3)
V3)1110.8 (3)
Z4
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.62 × 0.50 × 0.40
Data collection
DiffractometerBruker SMART 1K CCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
6709, 2571, 2326
Rint0.022
(sin θ/λ)max1)0.674
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.095, 1.06
No. of reflections2571
No. of parameters155
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.26, 0.15

Computer programs: SMART (Siemens, 1995), SAINT (Siemens, 1995), SHELXTL (Sheldrick, 1994), SHELXTL and local programs.

Selected geometric parameters (Å, º) top
C1—C21.3368 (16)B1—O21.3909 (15)
C1—B11.5321 (17)B1—O11.3910 (15)
C2—C211.4692 (15)
C2—C1—B1124.72 (11)O1—B1—C1125.50 (11)
C1—C2—C21126.86 (11)C11—O1—B1104.82 (9)
O2—B1—O1111.54 (10)C12—O2—B1105.06 (9)
O2—B1—C1122.96 (11)
B1—C1—C2—C21178.83 (11)C1—C2—C21—C22173.52 (11)
C2—C1—B1—O2179.17 (11)C1—C2—C21—C266.08 (18)
C2—C1—B1—O11.22 (19)
 

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