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ISSN: 2056-9890

4-(4,4-Di­fluoro-1,3,5,7-tetra­methyl-3a-aza-4a-azonia-4-borata-s-indacen-8-yl)benzo­nitrile

aDepartment of Chemistry, Shandong University, Jinan 250100, People's Republic of China, and bDepartment of Chemistry, Dezhou University, Dezhou 253023, People's Republic of China
*Correspondence e-mail: jianzhuang@ustb.edu.cn

(Received 23 February 2011; accepted 12 March 2011; online 19 March 2011)

The title compound, C20H18BF2N3, contains one C9BN2 (Bodipy) framework and one cyano­benzyl group. The Bodipy framework is essentially planar with a maximum deviation of 0.041 (2) Å. The introduction of two methyl groups at positions 1 and 7 of s-indacene in the Bodipy unit results in almost orthogonal configuration between the mean plane of the Bodipy unit and the cyano­benzyl group [dihedral angle = 89.78 (4)°].

Related literature

For the structures and optical properties of Bodipy dyes, see: Loudet & Burgess (2007[Loudet, A. & Burgess, K. (2007). Chem. Rev. 107, 4891-4932.]) and Feng et al. (2008[Feng, J. Q., Liang, B. L., Wang, D. L., Xue, L. & Li, X. Y. (2008). Org. Lett. 20, 4437-4440.]), respectively. For the relation between the crystal structures and optical properties of Bodipy compounds, see: Cui et al. (2007[Cui, A., Peng, X., Fan, J., Chen, X., Wu, Y. & Guo, B. (2007). J. Photochem. Photobiol. A, 186, 85-92.]); Broring et al.(2008[Broring, M., Kruger, R., Link, S., Kleeberg, C., Kohler, S., Xie, X., Ventura, B. & Flamigni, L. (2008). Chem. Eur. J. 14, 2976-2983.]).

[Scheme 1]

Experimental

Crystal data
  • C20H18BF2N3

  • Mr = 349.18

  • Monoclinic, P 21 /c

  • a = 7.6498 (3) Å

  • b = 11.3715 (5) Å

  • c = 21.555 (1) Å

  • β = 92.008 (4)°

  • V = 1873.91 (14) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.09 mm−1

  • T = 293 K

  • 0.20 × 0.18 × 0.16 mm

Data collection
  • Bruker SMART 1000 CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.]) Tmin = 0.983, Tmax = 0.986

  • 7304 measured reflections

  • 3286 independent reflections

  • 2240 reflections with I > 2σ(I)

  • Rint = 0.028

Refinement
  • R[F2 > 2σ(F2)] = 0.065

  • wR(F2) = 0.195

  • S = 1.07

  • 3286 reflections

  • 235 parameters

  • H-atom parameters constrained

  • Δρmax = 0.30 e Å−3

  • Δρmin = −0.25 e Å−3

Table 1
Selected bond lengths (Å)

F2—B1 1.382 (4)
N1—C5 1.350 (3)
N1—C9 1.400 (3)
N1—B1 1.535 (4)
F1—B1 1.384 (3)
N2—C3 1.346 (3)
N2—C10 1.408 (3)
N2—B1 1.545 (4)
C8—C10 1.390 (3)
C8—C9 1.398 (3)
C10—C1 1.429 (4)
C9—C7 1.426 (4)

Data collection: SMART (Bruker, 1996[Bruker (1996). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 1996[Bruker (1996). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

Fluorescent dyes, especially 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (Bodipy), have been extensively studied due to their advantageous photospectral properties including high photostability, sharp absorption and emission bands, relatively high absorption coefficient, high fluorescence quantum yields, and the extraordinary feature of excitation/emission wavelengths in the visible region (Loudet et al., 2007; Feng et al. 2008). Single crystal structural studies of these compounds have become increasingly important in revealing precisely the relation between their optical properties and molecular structures (Cui et al., 2007). As an extension of our work on the structural characterization of this field, the title compound, (I), is synthesized and characterized by x-ray diffraction, as shown in Fig. 1.

The compound (I) crystallizes in the monoclinic system with only one molecule per unit cell, and contains mainly one C9BN2 (Bodipy) framework and one cyanobenzyl unit. The C9BN2 (Bodipy) framework consisting of one central six-membered and two adjacent five-membered rings is essentially flat, with the maximum deviation from the least-squares mean plane being 0.041 Å. As shown in Table 1, the C—C and C—N bond lengths within C9BN2 (Bodipy) framework, without any clear distinction between single and double bonds, indicate the strongly delocalized π-system nature of the Bodipy framework. However, this π-electron delocalization is interrupted between the two B—N bonds (Broring et al. 2008). More interestingly, the introduction of two methyl groups onto C-1 and C-7 atoms in Bodipy moiety results in almostly orthogonal configuration between the mean plane of Bodipy moiety and cyanobenzyl unit with the dihedral angle of 89.78 (4)°, indicating the almost non-electronic coupling nature between these moieties. (Loudet et al., 2007).

Related literature top

For the structures and optical properties of Bodipy dyes, see: Loudet et al. (2007) and Feng et al. (2008), respectively. For the relation between the crystal structures and optical properties of Bodipy compounds, see: Cui et al. (2007); Broring et al.(2008).

Experimental top

To the mixture of 4-cyanobenzaldehyde (131 mg, 1 mmol) and 2,4-dimethylpyrrole (190 mg, 2.00 mmol) dissolved in CH2Cl2 (100 ml), one drop of TFAwas added. The resulting mixture was then stirred at room temperature under N2 atmosphere. When thin-layer chromatography (TLC) monitoring indicated the complete consumption of the aldehyde, a solution of DDQ (227 mg, 1 mmol) in CH2Cl2 (40 ml) was added and the reaction mixture was further stirred for another 15 min. After the addition of N, N-diisopropylethylamine (DIEA) (2 ml) into the mixture for 15 min, the BF3—OEt2 (2.0 ml) was added into the reaction mixture and stirring was continued for another 30 min. The resulting mixture was evaporated, and the residue was chromatographed on a silica gel column using CH2Cl2/hexane (1:1) as eluent. Repeated chromatography followed by recrystallization from CH2Cl2 and hexane gave the target compound as black-red crystals. Yield: 104 mg, 15%. Anal. for C20H18BF2N3: Calc. C, 68.79; H, 5.20; N, 12.03; Found: C, 68.10; H, 5.17; N, 12.81%. The No. of CCDC: 814146.

Refinement top

All H atoms were placed in geometrically idealized positions and treated as riding on their parent atoms with C–H distances of 0.96Å and Uiso(H)=1.5Ueq(C) for methyl H-atoms and C–H distances of 0.93Å and Uiso(H)=1.2Ueq(C) for other H-atoms.

Computing details top

Data collection: SMART (Bruker, 1996); cell refinement: SAINT (Bruker, 1996); data reduction: SAINT (Bruker, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at 30% probability level.
4-(4,4-Difluoro-1,3,5,7-tetramethyl-3a-aza-4a-azonia-4-borata-s- indacen-8-yl)benzonitrile top
Crystal data top
C20H18BF2N3F(000) = 728
Mr = 349.18Dx = 1.238 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3286 reflections
a = 7.6498 (3) Åθ = 2.3–25.0°
b = 11.3715 (5) ŵ = 0.09 mm1
c = 21.555 (1) ÅT = 293 K
β = 92.008 (4)°Block, red
V = 1873.91 (14) Å30.20 × 0.18 × 0.16 mm
Z = 4
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer
3286 independent reflections
Radiation source: fine-focus sealed tube2240 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.028
ϕ and ω scansθmax = 25.0°, θmin = 3.2°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 98
Tmin = 0.983, Tmax = 0.986k = 1313
7304 measured reflectionsl = 2516
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.065Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.195H-atom parameters constrained
S = 1.07 w = 1/[σ2(Fo2) + (0.1059P)2 + 0.276P]
where P = (Fo2 + 2Fc2)/3
3286 reflections(Δ/σ)max < 0.001
235 parametersΔρmax = 0.30 e Å3
0 restraintsΔρmin = 0.25 e Å3
Crystal data top
C20H18BF2N3V = 1873.91 (14) Å3
Mr = 349.18Z = 4
Monoclinic, P21/cMo Kα radiation
a = 7.6498 (3) ŵ = 0.09 mm1
b = 11.3715 (5) ÅT = 293 K
c = 21.555 (1) Å0.20 × 0.18 × 0.16 mm
β = 92.008 (4)°
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer
3286 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
2240 reflections with I > 2σ(I)
Tmin = 0.983, Tmax = 0.986Rint = 0.028
7304 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0650 restraints
wR(F2) = 0.195H-atom parameters constrained
S = 1.07Δρmax = 0.30 e Å3
3286 reflectionsΔρmin = 0.25 e Å3
235 parameters
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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
xyzUiso*/Ueq
F20.6736 (2)1.18071 (15)0.82647 (9)0.0706 (6)
N10.7514 (3)0.97876 (19)0.81048 (9)0.0409 (6)
F10.8040 (3)1.13260 (16)0.73783 (8)0.0750 (6)
N20.9776 (3)1.13074 (18)0.83306 (9)0.0384 (5)
C171.2845 (4)0.6972 (2)0.99641 (13)0.0491 (7)
C81.0075 (3)0.9342 (2)0.87582 (11)0.0376 (6)
C141.1043 (3)0.8502 (2)0.91690 (12)0.0391 (6)
C101.0737 (3)1.0468 (2)0.86812 (11)0.0388 (6)
C90.8499 (3)0.8989 (2)0.84668 (11)0.0405 (6)
C201.3795 (5)0.6205 (3)1.03874 (14)0.0619 (9)
C181.1552 (4)0.7687 (3)1.01831 (13)0.0623 (9)
H181.12930.76671.06010.075*
C161.3223 (4)0.7006 (3)0.93441 (14)0.0593 (8)
H161.40780.65130.91910.071*
C151.2329 (4)0.7774 (3)0.89494 (13)0.0555 (8)
H151.25950.78010.85320.067*
C21.2232 (4)1.2167 (3)0.86865 (14)0.0548 (8)
H21.30841.27390.87580.066*
C50.6123 (3)0.9205 (3)0.78539 (13)0.0495 (7)
C191.0646 (4)0.8426 (3)0.97863 (13)0.0579 (8)
H190.97480.88850.99360.069*
C40.9998 (4)1.3421 (3)0.80490 (16)0.0627 (9)
H4A0.88931.32660.78400.094*
H4B1.08141.37010.77540.094*
H4C0.98491.40080.83630.094*
C11.2306 (3)1.1032 (3)0.89043 (13)0.0484 (7)
C70.7648 (4)0.7874 (2)0.84295 (14)0.0510 (7)
C60.6190 (4)0.8041 (3)0.80502 (15)0.0588 (8)
H30.53730.74650.79420.071*
C31.0675 (4)1.2325 (2)0.83408 (12)0.0461 (7)
B10.7971 (4)1.1087 (3)0.80066 (14)0.0441 (8)
C110.8200 (5)0.6725 (3)0.87155 (19)0.0788 (11)
H5A0.92510.68360.89650.118*
H5B0.84110.61640.83930.118*
H5C0.72900.64380.89710.118*
C131.3786 (4)1.0532 (3)0.92990 (17)0.0722 (10)
H13A1.35440.97240.93920.108*
H13B1.39071.09710.96790.108*
H13C1.48521.05820.90780.108*
C120.4752 (4)0.9784 (3)0.74490 (17)0.0751 (10)
H1A0.50451.05980.73950.113*
H1B0.36400.97250.76400.113*
H1C0.46900.94020.70520.113*
N31.4528 (4)0.5619 (3)1.07363 (14)0.0836 (10)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
F20.0473 (9)0.0506 (10)0.1138 (16)0.0101 (8)0.0003 (10)0.0057 (10)
N10.0394 (11)0.0438 (13)0.0393 (12)0.0006 (10)0.0026 (9)0.0010 (10)
F10.0938 (14)0.0822 (13)0.0473 (11)0.0220 (11)0.0203 (9)0.0224 (9)
N20.0407 (11)0.0357 (12)0.0388 (12)0.0002 (9)0.0007 (9)0.0048 (10)
C170.0574 (17)0.0432 (16)0.0460 (17)0.0028 (13)0.0073 (13)0.0088 (13)
C80.0411 (13)0.0378 (15)0.0342 (13)0.0026 (11)0.0065 (11)0.0002 (11)
C140.0407 (13)0.0374 (14)0.0390 (15)0.0019 (11)0.0008 (11)0.0004 (12)
C100.0366 (12)0.0439 (15)0.0358 (14)0.0035 (11)0.0004 (10)0.0011 (12)
C90.0402 (13)0.0401 (15)0.0412 (14)0.0019 (11)0.0003 (11)0.0005 (12)
C200.084 (2)0.0478 (18)0.0534 (19)0.0053 (17)0.0091 (17)0.0070 (16)
C180.093 (2)0.0577 (19)0.0371 (16)0.0218 (18)0.0102 (16)0.0069 (15)
C160.0633 (18)0.064 (2)0.0510 (18)0.0255 (16)0.0034 (14)0.0056 (15)
C150.0631 (18)0.065 (2)0.0383 (15)0.0189 (16)0.0066 (13)0.0074 (14)
C20.0499 (16)0.0527 (19)0.0617 (19)0.0188 (14)0.0007 (14)0.0050 (15)
C50.0418 (14)0.0539 (18)0.0522 (16)0.0050 (13)0.0060 (13)0.0024 (14)
C190.078 (2)0.0560 (19)0.0410 (16)0.0208 (16)0.0178 (15)0.0044 (14)
C40.068 (2)0.0479 (18)0.072 (2)0.0081 (16)0.0016 (17)0.0148 (16)
C10.0425 (14)0.0533 (18)0.0489 (16)0.0033 (13)0.0048 (12)0.0027 (14)
C70.0492 (15)0.0412 (16)0.0626 (19)0.0040 (13)0.0011 (14)0.0014 (14)
C60.0496 (16)0.0511 (19)0.075 (2)0.0158 (14)0.0031 (15)0.0054 (16)
C30.0501 (15)0.0439 (16)0.0444 (16)0.0074 (13)0.0052 (12)0.0043 (13)
B10.0478 (17)0.0419 (18)0.0421 (17)0.0003 (14)0.0056 (14)0.0069 (15)
C110.079 (2)0.0441 (19)0.112 (3)0.0110 (17)0.013 (2)0.0184 (19)
C130.0506 (17)0.078 (2)0.086 (2)0.0111 (16)0.0224 (17)0.0132 (19)
C120.0591 (19)0.077 (2)0.086 (2)0.0084 (18)0.0288 (18)0.0025 (19)
N30.111 (2)0.0673 (19)0.0713 (19)0.0198 (18)0.0186 (17)0.0168 (16)
Geometric parameters (Å, º) top
F2—B11.382 (4)C2—C11.374 (4)
N1—C51.350 (3)C2—C31.394 (4)
N1—C91.400 (3)C2—H20.9300
N1—B11.535 (4)C5—C61.390 (4)
F1—B11.384 (3)C5—C121.494 (4)
N2—C31.346 (3)C19—H190.9300
N2—C101.408 (3)C4—C31.482 (4)
N2—B11.545 (4)C4—H4A0.9600
C17—C181.376 (4)C4—H4B0.9600
C17—C161.378 (4)C4—H4C0.9600
C17—C201.440 (4)C1—C131.504 (4)
C8—C101.390 (3)C7—C61.373 (4)
C8—C91.398 (3)C7—C111.500 (4)
C8—C141.483 (3)C6—H30.9300
C14—C191.378 (4)C11—H5A0.9600
C14—C151.382 (4)C11—H5B0.9600
C10—C11.429 (4)C11—H5C0.9600
C9—C71.426 (4)C13—H13A0.9600
C20—N31.138 (4)C13—H13B0.9600
C18—C191.371 (4)C13—H13C0.9600
C18—H180.9300C12—H1A0.9600
C16—C151.384 (4)C12—H1B0.9600
C16—H160.9300C12—H1C0.9600
C15—H150.9300
C5—N1—C9107.8 (2)C3—C4—H4B109.5
C5—N1—B1126.7 (2)H4A—C4—H4B109.5
C9—N1—B1125.5 (2)C3—C4—H4C109.5
C3—N2—C10108.5 (2)H4A—C4—H4C109.5
C3—N2—B1126.5 (2)H4B—C4—H4C109.5
C10—N2—B1125.0 (2)C2—C1—C10106.4 (2)
C18—C17—C16119.6 (2)C2—C1—C13124.7 (3)
C18—C17—C20119.5 (3)C10—C1—C13128.8 (3)
C16—C17—C20120.9 (3)C6—C7—C9105.7 (2)
C10—C8—C9121.5 (2)C6—C7—C11125.2 (3)
C10—C8—C14119.2 (2)C9—C7—C11129.1 (3)
C9—C8—C14119.2 (2)C7—C6—C5109.5 (2)
C19—C14—C15118.5 (2)C7—C6—H3125.3
C19—C14—C8119.6 (2)C5—C6—H3125.3
C15—C14—C8121.9 (2)N2—C3—C2108.9 (2)
C8—C10—N2120.2 (2)N2—C3—C4123.1 (3)
C8—C10—C1132.8 (2)C2—C3—C4127.9 (3)
N2—C10—C1107.0 (2)F2—B1—F1109.1 (2)
C8—C9—N1120.2 (2)F2—B1—N1110.6 (2)
C8—C9—C7131.7 (2)F1—B1—N1109.9 (2)
N1—C9—C7108.0 (2)F2—B1—N2109.5 (2)
N3—C20—C17177.9 (4)F1—B1—N2110.3 (2)
C19—C18—C17120.1 (3)N1—B1—N2107.3 (2)
C19—C18—H18119.9C7—C11—H5A109.5
C17—C18—H18119.9C7—C11—H5B109.5
C17—C16—C15119.9 (3)H5A—C11—H5B109.5
C17—C16—H16120.1C7—C11—H5C109.5
C15—C16—H16120.1H5A—C11—H5C109.5
C14—C15—C16120.7 (3)H5B—C11—H5C109.5
C14—C15—H15119.7C1—C13—H13A109.5
C16—C15—H15119.7C1—C13—H13B109.5
C1—C2—C3109.1 (2)H13A—C13—H13B109.5
C1—C2—H2125.4C1—C13—H13C109.5
C3—C2—H2125.4H13A—C13—H13C109.5
N1—C5—C6109.0 (2)H13B—C13—H13C109.5
N1—C5—C12123.0 (3)C5—C12—H1A109.5
C6—C5—C12128.0 (3)C5—C12—H1B109.5
C18—C19—C14121.1 (3)H1A—C12—H1B109.5
C18—C19—H19119.4C5—C12—H1C109.5
C14—C19—H19119.4H1A—C12—H1C109.5
C3—C4—H4A109.5H1B—C12—H1C109.5

Experimental details

Crystal data
Chemical formulaC20H18BF2N3
Mr349.18
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)7.6498 (3), 11.3715 (5), 21.555 (1)
β (°) 92.008 (4)
V3)1873.91 (14)
Z4
Radiation typeMo Kα
µ (mm1)0.09
Crystal size (mm)0.20 × 0.18 × 0.16
Data collection
DiffractometerBruker SMART 1000 CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.983, 0.986
No. of measured, independent and
observed [I > 2σ(I)] reflections
7304, 3286, 2240
Rint0.028
(sin θ/λ)max1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.065, 0.195, 1.07
No. of reflections3286
No. of parameters235
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.30, 0.25

Computer programs: SMART (Bruker, 1996), SAINT (Bruker, 1996), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Selected bond lengths (Å) top
F2—B11.382 (4)N2—C101.408 (3)
N1—C51.350 (3)N2—B11.545 (4)
N1—C91.400 (3)C8—C101.390 (3)
N1—B11.535 (4)C8—C91.398 (3)
F1—B11.384 (3)C10—C11.429 (4)
N2—C31.346 (3)C9—C71.426 (4)
 

References

First citationBroring, M., Kruger, R., Link, S., Kleeberg, C., Kohler, S., Xie, X., Ventura, B. & Flamigni, L. (2008). Chem. Eur. J. 14, 2976–2983.  PubMed CAS Google Scholar
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