8-(4-Bromo­phen­yl)-4,4-difluoro-1,3,5,7-tetra­methyl-4-bora-3a,4a-diaza-s-indacene

In the mol­ecule of the title compound, C₁₉H₁₈BBrF₂N₂, the bromo­benzene ring is almost perpendicular to the boron-dipyrromethene (BODIPY) fused-ring fragment [dihedral angle = 78.9 (1)°].

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.042
• wR factor = 0.115
• Data-to-parameter ratio = 13.6

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size .......       0.62 mm
PLAT380_ALERT_4_C Check Incorrectly? Oriented X(sp2)-Methyl Moiety         C1
PLAT380_ALERT_4_C Check Incorrectly? Oriented X(sp2)-Methyl Moiety         C2
PLAT380_ALERT_4_C Check Incorrectly? Oriented X(sp2)-Methyl Moiety         C8

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   4 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   3 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

We are interested in the synthesis of boron-dipyrromethene (BODIPY) dyes which are well known and have attracted much attention due to their use as fluorescence labels and biomolecule sensors in recent years (Wu et al., 2005; Trieflinger et al., 2005; Dost et al., 2006). So the investigation of their structures will be more helpful to understand their photophysical and photochemical properties profoundly (Qin et al., 2005). The crystal structure of compound (I) (Fig. 1) is reported here.

As shown in Fig. 1, the BODIPY skeleton formed by three conjugated heterocyclic rings (Table 1) is almost planar, with an r.m.s. deviation of 0.0378 (3) Å; the maximum deviations from the mean plane are 0.071 (3) Å for C12 and 0.060 (3) Å for C14. The two B—N distances are almost the same, implying the usual delocalization of the positive charge. Perhaps due to steric repulsion from the C1 and C3 methyl groups, the bormobenzene ring is strongly twisted out of the BODIPY mean plane, with a dihedral angle is 78.9 (1)°.

Related literature

For related literature, see: Dost et al. (2006); Qin et al. (2005); Trieflinger et al. (2005); Wu et al. (2005).

S2. Experimental

Compound (I) was prepared in one-pot reaction in dichloromethane (DCM). 8 mmol (0.8 ml) 2,4-dimethyl-pyrrole and 4 mmol (735 mg) 4-bromobenzaldehyde were dissolved in 150 ml absolute DCM, a few drops of trifluoroacetic acid was added immediately under an nitrogen atmosphere. After being stirred at room temperature overnight, 200 ml DCM was evaporated, then a solution of 2,3-dichloro-5,6-dicyano-benzoquinone (4 mmol) in DCM (30 ml) was added and continue stirring for half an hour, and followed by injecting 74 mmol triethylamine (8 ml) into the dark residue, after a while, 75 mmol (12 ml) boron trifluoride ethyl ether complex was injected slowly. After stirring for about 3 h, the solution was washed with an aqueous solution of NaHCO₃, the organic layer was dried over Na₂SO₄, and the solvent was evaporated by reduced pressure. Chromatography on silica column was carried out and eluted with ethyl acetate/petroleum ether (1:6 v/v) mixture. The collected red fraction was subsequently recrystallized from chloroform/hexane (1:4 v/v) to acquire 418 mg of (I) (yield 26%).

S3. Refinement

The H atoms were placed in idealized positions (C—H = 0.93–0.96 Å) and refined in riding mode with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(methyl C).

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL.

Figures

Fig. 1.

8-(4-Bromophenyl)-4,4-difluoro-1,3,5,7-tetramethyl- 4-bora-3a,4a-diaza-s-indacene

Crystal data

C19H18BBrF2N2	F(000) = 816
Mr = 403.07	Dx = 1.522 Mg m^−3
Monoclinic, P21/c	Melting point: 440 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 11.9874 (12) Å	Cell parameters from 3357 reflections
b = 8.2874 (7) Å	θ = 2.5–32.8°
c = 17.7140 (15) Å	µ = 2.36 mm^−1
β = 91.049 (7)°	T = 298 K
V = 1759.5 (3) Å^3	Block, dark red
Z = 4	0.62 × 0.45 × 0.10 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer	3090 independent reflections
Radiation source: fine-focus sealed tube	2354 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.024
Detector resolution: 9.21 pixels mm^-1	θmax = 25.0°, θmin = 2.7°
φ and ω scans	h = −14→12
Absorption correction: multi-scan (SADABS; Sheldrick, 1997)	k = −9→9
Tmin = 0.323, Tmax = 0.798	l = −21→21
7614 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.042	H-atom parameters constrained
wR(F^2) = 0.115	w = 1/[σ^2(Fo^2) + (0.0546P)^2 + 1.3326P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max = 0.001
3090 reflections	Δρmax = 0.55 e Å^−3
227 parameters	Δρmin = −0.61 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0059 (8)

Special details

Experimental. Mp.: 440–441 K;

¹H NMR (CDCl₃, 400 MHz): δ 7.641(d, 2H, Ar—H, J = 8.4 Hz), 7.171 (d, 2H, Ar—H, J = 8.4 Hz), 5.990 (s, 2H, pyrrole-H), 2.551 (s,CH₃—H, 6H), 1.141 (s, CH₃—H 6H).

¹³C NMR (CDCl₃, 400 MHz): δ 156.084, 143.088, 140.196, 134.139, 132.621, 131.360, 130.017, 123.443, 121.629, 14.826.

HRMS(EI): 402.0712, calculated: 402.0714.

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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	−0.03359 (4)	0.71112 (6)	0.04766 (2)	0.0755 (2)
C19	0.2385 (2)	0.2985 (4)	0.27304 (17)	0.0399 (7)
C18	0.2716 (2)	0.3598 (4)	0.34286 (17)	0.0401 (7)
C17	0.0493 (3)	0.5822 (4)	0.11723 (18)	0.0478 (8)
C16	0.1705 (2)	0.4002 (4)	0.21984 (17)	0.0393 (7)
C15	0.2712 (2)	0.1449 (4)	0.24924 (17)	0.0401 (7)
C14	0.2476 (3)	0.0557 (4)	0.18261 (18)	0.0442 (8)
C13	0.0560 (3)	0.4146 (4)	0.22579 (19)	0.0464 (8)
H13A	0.0197	0.3622	0.2647	0.056*
C12	0.3683 (3)	−0.0835 (4)	0.25676 (19)	0.0462 (8)
C11	−0.0048 (3)	0.5057 (4)	0.17462 (19)	0.0489 (8)
H11A	−0.0817	0.5151	0.1790	0.059*
C10	0.2232 (3)	0.4766 (4)	0.16093 (18)	0.0468 (8)
H10A	0.3000	0.4665	0.1560	0.056*
C9	0.3057 (3)	0.5012 (4)	0.44785 (19)	0.0534 (9)
H9A	0.3077	0.5825	0.4840	0.064*
C8	0.4453 (3)	−0.2100 (5)	0.2867 (2)	0.0626 (10)
H8A	0.4735	−0.1781	0.3356	0.094*
H8B	0.5064	−0.2232	0.2530	0.094*
H8C	0.4057	−0.3102	0.2910	0.094*
C7	0.3098 (3)	−0.0832 (4)	0.18801 (19)	0.0516 (8)
H7A	0.3125	−0.1640	0.1517	0.062*
C6	0.3586 (3)	0.3521 (5)	0.45480 (19)	0.0508 (8)
C5	0.1626 (3)	0.5677 (4)	0.10936 (19)	0.0519 (9)
H5A	0.1981	0.6187	0.0697	0.062*
C4	0.2501 (3)	0.5096 (4)	0.37948 (18)	0.0463 (8)
C3	0.1662 (3)	0.0949 (5)	0.1197 (2)	0.0588 (9)
H3A	0.1691	0.0123	0.0818	0.088*
H3B	0.1852	0.1969	0.0978	0.088*
H3C	0.0921	0.1004	0.1393	0.088*
C2	0.4261 (4)	0.2875 (5)	0.5194 (2)	0.0673 (11)
H2A	0.4518	0.1810	0.5074	0.101*
H2B	0.3809	0.2830	0.5635	0.101*
H2C	0.4890	0.3567	0.5288	0.101*
C1	0.1810 (3)	0.6495 (4)	0.3533 (2)	0.0570 (9)
H1A	0.1827	0.7324	0.3911	0.086*
H1B	0.1054	0.6148	0.3446	0.086*
H1C	0.2105	0.6913	0.3072	0.086*
N2	0.3388 (2)	0.2661 (3)	0.39129 (14)	0.0422 (6)
F2	0.50032 (16)	0.0954 (3)	0.37912 (12)	0.0653 (6)
F1	0.3431 (2)	−0.0139 (3)	0.42586 (11)	0.0672 (6)
N1	0.3444 (2)	0.0526 (3)	0.29409 (14)	0.0404 (6)
B	0.3845 (3)	0.0952 (5)	0.3751 (2)	0.0455 (9)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0897 (4)	0.0710 (3)	0.0646 (3)	0.0274 (2)	−0.0285 (2)	0.0028 (2)
C19	0.0325 (15)	0.0449 (19)	0.0424 (17)	−0.0023 (14)	0.0011 (13)	0.0054 (14)
C18	0.0355 (16)	0.0430 (18)	0.0418 (17)	0.0006 (14)	−0.0009 (13)	0.0025 (14)
C17	0.056 (2)	0.0401 (18)	0.0467 (18)	0.0091 (16)	−0.0155 (15)	−0.0060 (15)
C16	0.0382 (17)	0.0382 (17)	0.0413 (16)	0.0018 (13)	−0.0025 (13)	−0.0007 (14)
C15	0.0363 (16)	0.0418 (17)	0.0421 (17)	0.0005 (14)	−0.0015 (13)	0.0058 (15)
C14	0.0418 (17)	0.048 (2)	0.0429 (17)	−0.0043 (15)	0.0002 (14)	0.0012 (15)
C13	0.0440 (18)	0.0473 (19)	0.0480 (18)	0.0002 (15)	0.0017 (14)	0.0013 (16)
C12	0.0437 (18)	0.0439 (19)	0.0510 (19)	0.0034 (15)	0.0046 (15)	0.0030 (15)
C11	0.0398 (17)	0.050 (2)	0.057 (2)	0.0082 (15)	−0.0076 (15)	−0.0063 (17)
C10	0.0391 (17)	0.051 (2)	0.0503 (19)	0.0018 (15)	−0.0009 (14)	0.0056 (16)
C9	0.058 (2)	0.053 (2)	0.0484 (19)	−0.0030 (18)	−0.0031 (16)	−0.0070 (17)
C8	0.062 (2)	0.053 (2)	0.073 (3)	0.0149 (19)	−0.0003 (19)	0.000 (2)
C7	0.058 (2)	0.045 (2)	0.051 (2)	−0.0029 (17)	0.0021 (16)	−0.0046 (16)
C6	0.0499 (19)	0.057 (2)	0.0457 (19)	−0.0041 (17)	−0.0037 (15)	0.0013 (17)
C5	0.059 (2)	0.052 (2)	0.0447 (18)	−0.0019 (17)	−0.0055 (16)	0.0089 (16)
C4	0.0433 (18)	0.049 (2)	0.0467 (18)	−0.0012 (15)	0.0031 (14)	−0.0004 (15)
C3	0.058 (2)	0.065 (2)	0.052 (2)	−0.0001 (19)	−0.0130 (17)	−0.0078 (18)
C2	0.070 (3)	0.082 (3)	0.049 (2)	0.008 (2)	−0.0169 (19)	−0.005 (2)
C1	0.059 (2)	0.045 (2)	0.067 (2)	0.0029 (17)	−0.0035 (18)	−0.0070 (18)
N2	0.0410 (14)	0.0472 (16)	0.0381 (14)	0.0003 (12)	−0.0040 (11)	0.0037 (12)
F2	0.0450 (11)	0.0822 (16)	0.0682 (13)	0.0165 (11)	−0.0141 (9)	−0.0065 (12)
F1	0.0953 (16)	0.0553 (13)	0.0511 (12)	0.0014 (12)	0.0042 (11)	0.0145 (10)
N1	0.0377 (14)	0.0401 (15)	0.0434 (14)	0.0023 (12)	0.0014 (11)	0.0015 (12)
B	0.045 (2)	0.046 (2)	0.044 (2)	0.0046 (17)	−0.0031 (16)	0.0064 (17)

Geometric parameters (Å, º)

Br1—C17	1.898 (3)	C9—C6	1.393 (5)
C19—C18	1.388 (4)	C9—H9A	0.9300
C19—C15	1.400 (4)	C8—H8A	0.9600
C19—C16	1.495 (4)	C8—H8B	0.9600
C18—N2	1.401 (4)	C8—H8C	0.9600
C18—C4	1.426 (5)	C7—H7A	0.9300
C17—C11	1.371 (5)	C6—N2	1.349 (4)
C17—C5	1.373 (5)	C6—C2	1.489 (5)
C16—C13	1.383 (4)	C5—H5A	0.9300
C16—C10	1.384 (4)	C4—C1	1.494 (5)
C15—N1	1.400 (4)	C3—H3A	0.9600
C15—C14	1.417 (4)	C3—H3B	0.9600
C14—C7	1.374 (5)	C3—H3C	0.9600
C14—C3	1.504 (5)	C2—H2A	0.9600
C13—C11	1.377 (5)	C2—H2B	0.9600
C13—H13A	0.9300	C2—H2C	0.9600
C12—N1	1.342 (4)	C1—H1A	0.9600
C12—C7	1.394 (5)	C1—H1B	0.9600
C12—C8	1.488 (5)	C1—H1C	0.9600
C11—H11A	0.9300	B—N1	1.546 (5)
C10—C5	1.382 (4)	B—N2	1.548 (5)
C10—H10A	0.9300	B—F1	1.374 (4)
C9—C4	1.373 (5)	B—F2	1.388 (4)
C18—C19—C15	121.6 (3)	C12—C7—H7A	125.5
C18—C19—C16	119.9 (3)	N2—C6—C9	108.8 (3)
C15—C19—C16	118.4 (3)	N2—C6—C2	122.4 (3)
C19—C18—N2	119.6 (3)	C9—C6—C2	128.9 (3)
C19—C18—C4	132.3 (3)	C17—C5—C10	119.4 (3)
N2—C18—C4	108.1 (3)	C17—C5—H5A	120.3
C11—C17—C5	121.1 (3)	C10—C5—H5A	120.3
C11—C17—Br1	119.5 (3)	C9—C4—C18	105.5 (3)
C5—C17—Br1	119.4 (3)	C9—C4—C1	124.8 (3)
C13—C16—C10	119.1 (3)	C18—C4—C1	129.6 (3)
C13—C16—C19	122.1 (3)	C14—C3—H3A	109.5
C10—C16—C19	118.8 (3)	C14—C3—H3B	109.5
N1—C15—C19	120.1 (3)	H3A—C3—H3B	109.5
N1—C15—C14	107.5 (3)	C14—C3—H3C	109.5
C19—C15—C14	132.3 (3)	H3A—C3—H3C	109.5
C7—C14—C15	106.2 (3)	H3B—C3—H3C	109.5
C7—C14—C3	125.2 (3)	C6—C2—H2A	109.5
C15—C14—C3	128.5 (3)	C6—C2—H2B	109.5
C11—C13—C16	120.7 (3)	H2A—C2—H2B	109.5
C11—C13—H13A	119.7	C6—C2—H2C	109.5
C16—C13—H13A	119.7	H2A—C2—H2C	109.5
N1—C12—C7	108.7 (3)	H2B—C2—H2C	109.5
N1—C12—C8	123.6 (3)	C4—C1—H1A	109.5
C7—C12—C8	127.7 (3)	C4—C1—H1B	109.5
C17—C11—C13	119.3 (3)	H1A—C1—H1B	109.5
C17—C11—H11A	120.3	C4—C1—H1C	109.5
C13—C11—H11A	120.3	H1A—C1—H1C	109.5
C5—C10—C16	120.4 (3)	H1B—C1—H1C	109.5
C5—C10—H10A	119.8	C6—N2—C18	108.0 (3)
C16—C10—H10A	119.8	C6—N2—B	125.5 (3)
C4—C9—C6	109.6 (3)	C18—N2—B	126.6 (3)
C4—C9—H9A	125.2	C12—N1—C15	108.5 (3)
C6—C9—H9A	125.2	C12—N1—B	125.7 (3)
C12—C8—H8A	109.5	C15—N1—B	125.7 (3)
C12—C8—H8B	109.5	F1—B—F2	109.9 (3)
H8A—C8—H8B	109.5	F1—B—N1	110.3 (3)
C12—C8—H8C	109.5	F2—B—N1	110.0 (3)
H8A—C8—H8C	109.5	F1—B—N2	110.3 (3)
H8B—C8—H8C	109.5	F2—B—N2	110.3 (3)
C14—C7—C12	109.0 (3)	N1—B—N2	106.0 (3)
C14—C7—H7A	125.5
C15—C19—C18—N2	−0.5 (4)	C6—C9—C4—C1	178.0 (3)
C16—C19—C18—N2	−177.7 (3)	C19—C18—C4—C9	−179.8 (3)
C15—C19—C18—C4	179.9 (3)	N2—C18—C4—C9	0.6 (4)
C16—C19—C18—C4	2.7 (5)	C19—C18—C4—C1	1.4 (6)
C18—C19—C16—C13	−82.5 (4)	N2—C18—C4—C1	−178.2 (3)
C15—C19—C16—C13	100.2 (4)	C9—C6—N2—C18	−0.4 (4)
C18—C19—C16—C10	100.4 (4)	C2—C6—N2—C18	178.9 (3)
C15—C19—C16—C10	−76.9 (4)	C9—C6—N2—B	178.6 (3)
C18—C19—C15—N1	−3.8 (4)	C2—C6—N2—B	−2.0 (5)
C16—C19—C15—N1	173.4 (3)	C19—C18—N2—C6	−179.8 (3)
C18—C19—C15—C14	178.8 (3)	C4—C18—N2—C6	−0.1 (3)
C16—C19—C15—C14	−3.9 (5)	C19—C18—N2—B	1.2 (4)
N1—C15—C14—C7	−2.2 (3)	C4—C18—N2—B	−179.1 (3)
C19—C15—C14—C7	175.4 (3)	C7—C12—N1—C15	−1.0 (4)
N1—C15—C14—C3	174.1 (3)	C8—C12—N1—C15	179.0 (3)
C19—C15—C14—C3	−8.3 (6)	C7—C12—N1—B	175.2 (3)
C10—C16—C13—C11	−1.1 (5)	C8—C12—N1—B	−4.7 (5)
C19—C16—C13—C11	−178.2 (3)	C19—C15—N1—C12	−175.9 (3)
C5—C17—C11—C13	0.9 (5)	C14—C15—N1—C12	2.0 (3)
Br1—C17—C11—C13	−178.8 (2)	C19—C15—N1—B	7.8 (4)
C16—C13—C11—C17	0.2 (5)	C14—C15—N1—B	−174.2 (3)
C13—C16—C10—C5	0.9 (5)	C12—N1—B—F1	−62.6 (4)
C19—C16—C10—C5	178.1 (3)	C15—N1—B—F1	113.0 (3)
C15—C14—C7—C12	1.6 (4)	C12—N1—B—F2	58.8 (4)
C3—C14—C7—C12	−174.9 (3)	C15—N1—B—F2	−125.6 (3)
N1—C12—C7—C14	−0.4 (4)	C12—N1—B—N2	178.0 (3)
C8—C12—C7—C14	179.6 (3)	C15—N1—B—N2	−6.4 (4)
C4—C9—C6—N2	0.8 (4)	C6—N2—B—F1	63.6 (4)
C4—C9—C6—C2	−178.5 (4)	C18—N2—B—F1	−117.5 (3)
C11—C17—C5—C10	−1.1 (5)	C6—N2—B—F2	−58.0 (4)
Br1—C17—C5—C10	178.7 (3)	C18—N2—B—F2	120.9 (3)
C16—C10—C5—C17	0.2 (5)	C6—N2—B—N1	−177.0 (3)
C6—C9—C4—C18	−0.8 (4)	C18—N2—B—N1	1.9 (4)