9-Ethyl-1,4-dimethyl-6-(4,4,5,5-tetra­methyl-1,3,2-dioxaborolan-2-yl)-9H-carbazole and 6-bromo-9-ethyl-1,4-dimethyl-9H-carbazole

The title carbazolyl boronic ester, C₂₂H₂₈BNO₂, (I), is a building block for the synthesis of new carbazole derivatives of potential utility as pharmaceutically active compounds. The crystal structure of (I) and of the title bromo­carbazole com­pound, C₁₆H₁₆BrN, (II), the synthetic precursor of (I), were solved and analysed with the aim of understanding the lack of reactivity of (I) under Suzuki cross-coupling reaction conditions. In both structures, the methyl groups are coplanar with the carbazole ring system, and the ethyl group lies out of the carbazole plane. The dioxaborolane ring of boronic ester (I) adopts a half-chair conformation but lies approximately in a planar orientation with respect of the carbazole ring system, whereas the Br atom of (II) is coplanar with the carbazole plane. In (I), the carbazole-boronic ester C-B bond length is 1.5435 (14) Å, which is somewhat shorter than the usual value of 1.57 Å.

S1. Comment

Ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole) is a well known alkaloid with antitumor properties, acting as a DNA intercalating agent and inhibiting the activity of topoisomerase II. Many structural modifications of the original molecule have been designed in order to obtain derivatives with a better pharmacological profile. In particular, 9-hydroxyellipticine, Celiptium, has been shown to possess a higher DNA affinity than ellipticine itself, measured on L1210 mice leukaemia, and a lack of toxicity at therapeutic doses (Le Pecq et al., 1974; Searle et al., 1984; Poljakova et al., 2007; Ho & Hsieh, 2006).

We have described recently a general method for the synthesis of 9-alkyl-1,4-dimethyl-6- (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9H-carbazoles starting from 6-bromo-9-alkyl-1,4-dimethyl-9H-carbazole (Caruso et al., 2007). Using the similar synthesis pathway we were able to prepare 9-ethyl-1,4-dimethyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) -9H-carbazole, (I), from 6-bromo-1,4-dimethyl-9H-carbazole, with 6-bromo-9-ethyl-1,4-dimethyl-9H-carbazole, (II), as intermediate product. The crystal structures of the final product (I) and the intermediate (II) are described in this article. The boronic acids and esters constitute very interesting and reactive intermediates for the preparation of various compounds; for example they can be used in metal-catalyzed reactions of the Suzuki type (Suzuki, 1999; Gérard et al., 2006). Metallo-catalysed cross-coupling chemistry has considerably upset the existing medicinal chemistry strategies, making the majority of classical synthetic pathways obsolete. This generally convergent strategy, which is the source of great diversity, makes possible the synthesis of a wide range of chemical libraries starting from a few valuable scaffolds. In this context, we are interested in the production of boronic compounds which are directly carriers of a potent therapeutic skeleton and have cancerology applications (de Koning et al., 2000). However, the title boronic ester has a lower activity than expected, and we undertaken the crystal structure analysis of (I) and (II) to find an explanation.

Figs. 1 and 2 show views of the molecules of (I) and (II), respectively. The asymmetric unit of (I) contains one molecule and that of (II) contains two molecules.

Structure analysis showed that the carbazole cycle is planar in both compounds. The methyl substituents are positioned coplanar with respect to the aromatic rings. In both structures, the ethyl group takes the same conformation: it lies out of the carbazole plane. The dihedral angle (C9A—N9—C10—C11) between the carbazole plane and the plane formed by the ethyl C and carbazole N atoms is -69.9 (1)° in (I) and thus the ethyl group is oriented `downwards' with respect to the carbazole plane. In (II), the dihedral angles are 96.2 (3) and 93.7 (3)°: the ethyl group is oriented `upwards' with respect to the carbazole ring system.

The dioxaborolane ring of (I) is in a half-chair conformation, with an O1—C14—C15—O2 torsion angle of 30.80 (9)°. The BO₂ group is rotated away from the plane of the carbazole ring system by 10.90 (5)°, and the angle between the diaxoborolane ring and the carbazole plane is 16.85 (4)°. The bond length between the carbazole ring and the dioxaborolane ring is 1.5435 (14) Å, which is smaller than usual (1.57 Å; Hall, 2005). Thus, it seems that the boron electron deficiency pumps the π electrons from the carbazole ring system, and this could be a reason for the lower reactivity of (I).

In the crystal packing of (I), the carbazole ring systems stack in parallel planes, forming columns in the b-axis direction. The interplanar spacing is between 3.50 and 3.54 Å. The stacking appears to be the principal interaction in the crystal packing. [There is some repetition in these last two paragraphs; is the spacing actually the same in both compounds or should this first paragraph be omitted? If it is to be retained the wording in the following paragraph should be altered to avoid repetition.]

In (II), the carbazole ring systems stack in parallel planes, forming columns in the b-axis direction. The interplanar spacing is 3.50–3.54 Å. Columns in the b-axis direction are also formed in (I). However, in this case, each second ring in the column is slipped (in the a direction) and the planes of neighbouring carbazole ring systems in the columns are twisted; the angle formed between the planes is about 37°.

Related literature

For related literature, see: Caruso et al. (2007); Gérard et al. (2006); Hall (2005); Ho & Hsieh (2006); Koning et al. (2000); Le Pecq, Xuong, Gosse & Paoletti (1974); Poljakova et al. (2007); Searle et al. (1984); Suzuki (1999).

S2. Experimental

6-Bromo-1,4-dimethyl-9H-carbazole was prepared by the reaction of 5-bromoindole with hexane-2,4-dione in the presence of p-toluenesulphonic acid. 6-Bromo-1,4-dimethyl-9H-carbazole was N-ethylated by iodoethane/sodium hydride under standard conditions to give (II). Lithiation–boronation of this intermediate, at very low temperature [specify temeperature?], using n-BuLi, triisopropyl borate and pinacol gave (II) after a typical hydrolytic work-up. Transparent crystals of (I) and (II) suitable for X-ray analysis were grown from an acetonitrile solution at room temperature. [Please specify quantities of reagents throughout.]

S3. Refinement

The Flack parameter for (II) was determined with a BASF/TWIN refinement. For (I), all H atoms were located via a difference Fourier map and refined with isotropic atomic displacement parameters [C—H = 0.948 (17)–1.031 (16) Å]. For (II), H atoms were placed in calculated positions and treated as riding on the parent atoms in the ideal geometry (C—H = 0.93–0.97 Å).

Computing details

For both compounds, data collection: APEX2 (Bruker, 2006); cell refinement: APEX2 (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXTL (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).

Figures

	Fig. 1. The asymmetric unit of (I), showing the labelling of the non-H atoms. Displacement ellipsoids are shown at the 50% probability levels; H atoms are drawn as small circles of arbitrary radii.
	Fig. 2. One of the two molecules of the asymmetric unit of (II), showing the labelling of the non-H atoms. Displacement ellipsoids are shown at the 50% probability levels; H atoms are drawn as small circles of arbitrary radiius.

(I) 9-Ethyl-1,4-dimethyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)- 9H-carbazole

Crystal data

C22H28BNO2	F(000) = 752
Mr = 349.26	Dx = 1.183 Mg m^−3
Monoclinic, P21/c	Melting point: 415 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 8.6357 (3) Å	Cell parameters from 9716 reflections
b = 8.1068 (3) Å	θ = 2.4–34.7°
c = 28.2057 (9) Å	µ = 0.07 mm^−1
β = 96.673 (2)°	T = 150 K
V = 1961.24 (12) Å^3	Plate, colourless
Z = 4	0.51 × 0.36 × 0.35 mm

Data collection

Bruker APEXII CCD area-detector diffractometer	6728 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.048
Graphite monochromator	θmax = 34.9°, θmin = 2.6°
phi and ω scans	h = −13→13
96221 measured reflections	k = −12→13
8529 independent reflections	l = −44→45

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.054	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.143	All H-atom parameters refined
S = 1.08	w = 1/[σ^2(Fo^2) + (0.068P)^2 + 0.5909P] where P = (Fo^2 + 2Fc^2)/3
8529 reflections	(Δ/σ)max < 0.001
347 parameters	Δρmax = 0.59 e Å^−3
0 restraints	Δρmin = −0.29 e Å^−3

Special details

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
C6	0.35498 (10)	0.80818 (11)	0.10426 (3)	0.01580 (15)
C7	0.24194 (11)	0.86419 (12)	0.13295 (3)	0.01723 (16)
H7	0.1380 (17)	0.8936 (19)	0.1176 (5)	0.028 (4)*
C8	0.27233 (10)	0.87927 (12)	0.18199 (3)	0.01641 (16)
H8	0.1907 (16)	0.9200 (19)	0.2010 (5)	0.024 (3)*
C8A	0.42282 (10)	0.84174 (11)	0.20297 (3)	0.01377 (15)
N9	0.48382 (9)	0.85695 (10)	0.25028 (3)	0.01475 (14)
C9A	0.64091 (10)	0.81134 (11)	0.25445 (3)	0.01404 (15)
C1	0.75276 (11)	0.81416 (11)	0.29491 (3)	0.01651 (16)
C2	0.90150 (11)	0.76301 (12)	0.28726 (4)	0.01898 (17)
H2	0.9851 (17)	0.7638 (18)	0.3151 (5)	0.023 (3)*
C3	0.94038 (11)	0.71291 (12)	0.24271 (4)	0.01873 (17)
H3	1.0473 (18)	0.6738 (19)	0.2392 (5)	0.026 (4)*
C4	0.83144 (10)	0.71556 (11)	0.20249 (3)	0.01559 (15)
C4A	0.67993 (10)	0.76710 (10)	0.20872 (3)	0.01342 (14)
C4B	0.54021 (10)	0.78717 (10)	0.17550 (3)	0.01340 (14)
C5	0.50407 (10)	0.76893 (11)	0.12620 (3)	0.01498 (15)
H5	0.5835 (17)	0.7298 (18)	0.1061 (5)	0.021 (3)*
C10	0.38311 (11)	0.86188 (11)	0.28845 (3)	0.01520 (15)
H10A	0.2875 (15)	0.9180 (17)	0.2753 (4)	0.015 (3)*
H10B	0.4342 (15)	0.9303 (17)	0.3142 (5)	0.018 (3)*
C11	0.34604 (11)	0.69040 (12)	0.30542 (3)	0.01821 (17)
H11A	0.3019 (17)	0.6226 (19)	0.2786 (5)	0.025 (4)*
H11B	0.4391 (17)	0.6366 (18)	0.3214 (5)	0.024 (3)*
H11C	0.2677 (17)	0.6978 (18)	0.3282 (5)	0.025 (4)*
C12	0.87335 (11)	0.66028 (13)	0.15478 (4)	0.02052 (18)
H12A	0.8595 (18)	0.7489 (19)	0.1319 (6)	0.029 (4)*
H12B	0.8066 (17)	0.5649 (19)	0.1428 (5)	0.028 (4)*
H12C	0.9835 (17)	0.6243 (19)	0.1570 (5)	0.026 (4)*
C13	0.72279 (12)	0.87230 (15)	0.34370 (4)	0.0233 (2)
H13A	0.6832 (18)	0.985 (2)	0.3427 (5)	0.031 (4)*
H13B	0.8215 (19)	0.872 (2)	0.3659 (6)	0.032 (4)*
H13C	0.6527 (19)	0.7996 (19)	0.3575 (6)	0.030 (4)*
B1	0.31304 (12)	0.78903 (13)	0.04984 (4)	0.01688 (18)
O2	0.17617 (8)	0.84516 (9)	0.02549 (2)	0.01970 (14)
O1	0.40869 (8)	0.71309 (10)	0.02090 (2)	0.02022 (14)
C14	0.31605 (12)	0.68979 (14)	−0.02529 (3)	0.02069 (18)
C15	0.19294 (12)	0.83023 (13)	−0.02531 (3)	0.01973 (18)
C16	0.42376 (15)	0.70069 (19)	−0.06399 (4)	0.0317 (3)
H16A	0.477 (2)	0.803 (2)	−0.0619 (6)	0.035 (4)*
H16B	0.497 (2)	0.604 (2)	−0.0612 (6)	0.043 (5)*
H16C	0.364 (2)	0.696 (2)	−0.0959 (7)	0.046 (5)*
C17	0.24447 (14)	0.51831 (15)	−0.02465 (4)	0.0273 (2)
H17A	0.1744 (18)	0.510 (2)	0.0011 (5)	0.033 (4)*
H17B	0.1794 (18)	0.493 (2)	−0.0558 (6)	0.031 (4)*
H17C	0.3281 (19)	0.436 (2)	−0.0189 (6)	0.036 (4)*
C18	0.03524 (13)	0.79172 (16)	−0.05233 (4)	0.0272 (2)
H18A	−0.0093 (18)	0.693 (2)	−0.0394 (6)	0.031 (4)*
H18B	0.044 (2)	0.771 (2)	−0.0879 (6)	0.037 (4)*
H18C	−0.0316 (19)	0.885 (2)	−0.0506 (6)	0.033 (4)*
C19	0.25054 (15)	0.99612 (16)	−0.04130 (4)	0.0297 (2)
H19A	0.356 (2)	1.023 (2)	−0.0237 (6)	0.041 (4)*
H19B	0.2639 (19)	0.992 (2)	−0.0771 (6)	0.040 (4)*
H19C	0.1754 (19)	1.082 (2)	−0.0352 (6)	0.033 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C6	0.0156 (4)	0.0168 (4)	0.0149 (3)	0.0006 (3)	0.0014 (3)	0.0016 (3)
C7	0.0148 (4)	0.0196 (4)	0.0171 (4)	0.0024 (3)	0.0012 (3)	0.0027 (3)
C8	0.0140 (3)	0.0185 (4)	0.0169 (4)	0.0029 (3)	0.0026 (3)	0.0010 (3)
C8A	0.0141 (3)	0.0133 (3)	0.0139 (3)	0.0001 (3)	0.0017 (3)	0.0005 (3)
N9	0.0141 (3)	0.0165 (3)	0.0137 (3)	0.0014 (2)	0.0019 (2)	0.0002 (2)
C9A	0.0134 (3)	0.0121 (3)	0.0163 (3)	−0.0006 (3)	0.0007 (3)	0.0005 (3)
C1	0.0163 (4)	0.0158 (4)	0.0169 (4)	−0.0016 (3)	−0.0003 (3)	0.0002 (3)
C2	0.0148 (4)	0.0209 (4)	0.0204 (4)	−0.0018 (3)	−0.0015 (3)	0.0012 (3)
C3	0.0124 (3)	0.0211 (4)	0.0223 (4)	−0.0010 (3)	0.0006 (3)	0.0018 (3)
C4	0.0127 (3)	0.0147 (4)	0.0195 (4)	−0.0012 (3)	0.0023 (3)	0.0009 (3)
C4A	0.0130 (3)	0.0113 (3)	0.0159 (3)	−0.0008 (3)	0.0014 (3)	0.0006 (3)
C4B	0.0128 (3)	0.0122 (3)	0.0152 (3)	0.0001 (3)	0.0018 (3)	0.0009 (3)
C5	0.0146 (3)	0.0149 (4)	0.0156 (3)	−0.0002 (3)	0.0025 (3)	0.0007 (3)
C10	0.0169 (4)	0.0135 (3)	0.0156 (3)	0.0019 (3)	0.0034 (3)	−0.0016 (3)
C11	0.0194 (4)	0.0162 (4)	0.0194 (4)	−0.0007 (3)	0.0042 (3)	0.0001 (3)
C12	0.0159 (4)	0.0246 (5)	0.0219 (4)	0.0016 (3)	0.0056 (3)	−0.0001 (4)
C13	0.0218 (4)	0.0302 (5)	0.0171 (4)	−0.0004 (4)	−0.0012 (3)	−0.0041 (4)
B1	0.0159 (4)	0.0195 (4)	0.0150 (4)	0.0004 (3)	0.0010 (3)	0.0025 (3)
O2	0.0182 (3)	0.0255 (3)	0.0149 (3)	0.0045 (3)	0.0000 (2)	0.0017 (2)
O1	0.0169 (3)	0.0298 (4)	0.0137 (3)	0.0040 (3)	0.0003 (2)	0.0006 (3)
C14	0.0199 (4)	0.0290 (5)	0.0128 (3)	0.0029 (4)	0.0004 (3)	0.0007 (3)
C15	0.0200 (4)	0.0247 (4)	0.0138 (4)	0.0012 (3)	−0.0009 (3)	0.0033 (3)
C16	0.0284 (5)	0.0500 (8)	0.0175 (4)	0.0055 (5)	0.0063 (4)	0.0021 (5)
C17	0.0314 (5)	0.0260 (5)	0.0238 (5)	0.0023 (4)	−0.0003 (4)	−0.0032 (4)
C18	0.0221 (5)	0.0356 (6)	0.0220 (5)	0.0021 (4)	−0.0051 (4)	0.0022 (4)
C19	0.0351 (6)	0.0281 (5)	0.0251 (5)	−0.0026 (5)	−0.0004 (4)	0.0089 (4)

Geometric parameters (Å, º)

C6—C5	1.3987 (13)	C11—H11C	0.988 (15)
C6—C7	1.4132 (13)	C12—H12A	0.964 (16)
C6—B1	1.5435 (14)	C12—H12B	1.000 (15)
C7—C8	1.3832 (13)	C12—H12C	0.990 (15)
C7—H7	0.979 (15)	C13—H13A	0.977 (16)
C8—C8A	1.3975 (12)	C13—H13B	0.998 (16)
C8—H8	0.991 (14)	C13—H13C	0.959 (16)
C8A—N9	1.3820 (11)	B1—O1	1.3725 (13)
C8A—C4B	1.4163 (12)	B1—O2	1.3738 (12)
N9—C9A	1.3978 (11)	O2—C15	1.4617 (12)
N9—C10	1.4612 (11)	O1—C14	1.4599 (12)
C9A—C1	1.4071 (12)	C14—C16	1.5167 (15)
C9A—C4A	1.4165 (12)	C14—C17	1.5223 (16)
C1—C2	1.3903 (13)	C14—C15	1.5576 (14)
C1—C13	1.5051 (14)	C15—C18	1.5139 (15)
C2—C3	1.3981 (14)	C15—C19	1.5204 (16)
C2—H2	1.003 (15)	C16—H16A	0.948 (17)
C3—C4	1.3873 (13)	C16—H16B	1.006 (18)
C3—H3	0.993 (15)	C16—H16C	0.985 (19)
C4—C4A	1.4038 (12)	C17—H17A	1.000 (15)
C4—C12	1.5021 (14)	C17—H17B	1.006 (16)
C4A—C4B	1.4483 (12)	C17—H17C	0.985 (17)
C4B—C5	1.3973 (12)	C18—H18A	0.979 (16)
C5—H5	0.991 (14)	C18—H18B	1.029 (17)
C10—C11	1.5164 (13)	C18—H18C	0.954 (17)
C10—H10A	0.977 (13)	C19—H19A	1.010 (17)
C10—H10B	0.976 (14)	C19—H19B	1.031 (16)
C11—H11A	0.975 (15)	C19—H19C	0.979 (17)
C11—H11B	0.977 (15)
C5—C6—C7	118.78 (8)	C4—C12—H12B	110.1 (9)
C5—C6—B1	120.97 (8)	H12A—C12—H12B	109.2 (13)
C7—C6—B1	120.25 (8)	C4—C12—H12C	111.2 (8)
C8—C7—C6	122.52 (8)	H12A—C12—H12C	107.7 (13)
C8—C7—H7	118.5 (9)	H12B—C12—H12C	107.8 (12)
C6—C7—H7	119.0 (9)	C1—C13—H13A	111.3 (9)
C7—C8—C8A	117.59 (8)	C1—C13—H13B	110.5 (9)
C7—C8—H8	120.4 (8)	H13A—C13—H13B	106.8 (13)
C8A—C8—H8	121.9 (8)	C1—C13—H13C	111.2 (9)
N9—C8A—C8	128.37 (8)	H13A—C13—H13C	110.7 (13)
N9—C8A—C4B	109.83 (7)	H13B—C13—H13C	106.1 (13)
C8—C8A—C4B	121.73 (8)	O1—B1—O2	113.17 (8)
C8A—N9—C9A	108.36 (7)	O1—B1—C6	123.27 (8)
C8A—N9—C10	121.42 (7)	O2—B1—C6	123.56 (9)
C9A—N9—C10	126.88 (7)	B1—O2—C15	106.57 (7)
N9—C9A—C1	129.20 (8)	B1—O1—C14	106.47 (7)
N9—C9A—C4A	108.76 (7)	O1—C14—C16	108.45 (8)
C1—C9A—C4A	121.95 (8)	O1—C14—C17	106.78 (8)
C2—C1—C9A	115.39 (8)	C16—C14—C17	110.21 (10)
C2—C1—C13	119.70 (8)	O1—C14—C15	102.06 (8)
C9A—C1—C13	124.88 (9)	C16—C14—C15	115.65 (9)
C1—C2—C3	123.29 (9)	C17—C14—C15	112.92 (9)
C1—C2—H2	118.1 (8)	O2—C15—C18	108.95 (8)
C3—C2—H2	118.7 (8)	O2—C15—C19	106.89 (8)
C4—C3—C2	121.30 (9)	C18—C15—C19	109.83 (9)
C4—C3—H3	118.2 (9)	O2—C15—C14	101.86 (7)
C2—C3—H3	120.5 (9)	C18—C15—C14	115.05 (9)
C3—C4—C4A	117.10 (8)	C19—C15—C14	113.57 (9)
C3—C4—C12	121.13 (8)	C14—C16—H16A	109.9 (10)
C4A—C4—C12	121.74 (8)	C14—C16—H16B	109.4 (10)
C4—C4A—C9A	120.87 (8)	H16A—C16—H16B	112.4 (14)
C4—C4A—C4B	132.14 (8)	C14—C16—H16C	110.9 (11)
C9A—C4A—C4B	106.99 (7)	H16A—C16—H16C	106.7 (15)
C5—C4B—C8A	119.09 (8)	H16B—C16—H16C	107.5 (14)
C5—C4B—C4A	134.83 (8)	C14—C17—H17A	110.7 (10)
C8A—C4B—C4A	106.06 (7)	C14—C17—H17B	111.1 (9)
C4B—C5—C6	120.25 (8)	H17A—C17—H17B	107.2 (12)
C4B—C5—H5	120.9 (8)	C14—C17—H17C	109.4 (10)
C6—C5—H5	118.9 (8)	H17A—C17—H17C	109.1 (13)
N9—C10—C11	111.90 (7)	H17B—C17—H17C	109.3 (13)
N9—C10—H10A	106.3 (7)	C15—C18—H18A	110.6 (9)
C11—C10—H10A	110.3 (8)	C15—C18—H18B	111.1 (10)
N9—C10—H10B	107.8 (8)	H18A—C18—H18B	107.6 (13)
C11—C10—H10B	112.3 (8)	C15—C18—H18C	109.0 (10)
H10A—C10—H10B	107.9 (11)	H18A—C18—H18C	111.3 (13)
C10—C11—H11A	110.5 (9)	H18B—C18—H18C	107.2 (13)
C10—C11—H11B	111.2 (9)	C15—C19—H19A	110.6 (10)
H11A—C11—H11B	109.4 (12)	C15—C19—H19B	109.7 (10)
C10—C11—H11C	109.6 (9)	H19A—C19—H19B	107.0 (13)
H11A—C11—H11C	107.6 (12)	C15—C19—H19C	109.2 (10)
H11B—C11—H11C	108.4 (12)	H19A—C19—H19C	109.9 (14)
C4—C12—H12A	110.7 (9)	H19B—C19—H19C	110.4 (13)
O1—C18—C19—O2	−44.71 (3)

(II) 6-bromo-9-ethyl-1,4-dimethyl-9H-carbazole

Crystal data

C16H16BrN	F(000) = 616
Mr = 302.21	Dx = 1.513 Mg m^−3
Monoclinic, P21	Melting point: 363 K
Hall symbol: P 2yb	Mo Kα radiation, λ = 0.71073 Å
a = 15.3210 (14) Å	Cell parameters from 5721 reflections
b = 4.6518 (5) Å	θ = 2.7–29.9°
c = 18.6647 (17) Å	µ = 3.08 mm^−1
β = 94.239 (5)°	T = 150 K
V = 1326.6 (2) Å^3	Prism, colourless
Z = 4	0.41 × 0.36 × 0.34 mm

Data collection

Bruker APEXII CCD area-detector diffractometer	9080 independent reflections
Radiation source: sealed tube	7897 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.033
phi and ω scans	θmax = 32.0°, θmin = 2.7°
Absorption correction: numerical (SAINT; Bruker, 2006)	h = −22→22
Tmin = 0.366, Tmax = 0.508	k = −6→6
32267 measured reflections	l = −26→27

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)] = 0.030	H-atom parameters constrained
wR(F^2) = 0.067	w = 1/[σ^2(Fo^2) + (0.0358P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.01	(Δ/σ)max = 0.002
9080 reflections	Δρmax = 0.59 e Å^−3
332 parameters	Δρmin = −0.33 e Å^−3
1 restraint	Absolute structure: Flack (1983), 3979 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.265 (4)

Special details

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
C11	0.77412 (10)	0.5447 (4)	0.41137 (9)	0.0212 (3)
C12	0.72214 (12)	0.6594 (4)	0.35457 (10)	0.0253 (4)
H12	0.7331	0.6045	0.3082	0.030*
C13	0.65427 (11)	0.8526 (4)	0.36330 (10)	0.0254 (3)
H13	0.6211	0.9194	0.3230	0.030*
C14	0.63495 (10)	0.9480 (4)	0.43085 (9)	0.0204 (3)
C14A	0.68556 (9)	0.8360 (3)	0.48968 (9)	0.0177 (3)
C14B	0.68387 (10)	0.8794 (4)	0.56649 (9)	0.0187 (3)
C15	0.63271 (10)	1.0471 (4)	0.60894 (9)	0.0209 (3)
H15	0.5887	1.1653	0.5884	0.025*
C16	0.64958 (10)	1.0318 (4)	0.68285 (9)	0.0238 (3)
C17	0.71606 (11)	0.8605 (4)	0.71549 (10)	0.0257 (4)
H17	0.7261	0.8597	0.7652	0.031*
C18	0.76699 (11)	0.6920 (4)	0.67402 (9)	0.0235 (3)
H18	0.8113	0.5763	0.6950	0.028*
C18A	0.74968 (9)	0.7012 (4)	0.59950 (9)	0.0187 (3)
N19	0.79060 (8)	0.5521 (3)	0.54743 (8)	0.0198 (3)
C19A	0.75345 (10)	0.6321 (4)	0.48002 (9)	0.0185 (3)
Br11	0.577329 (12)	1.24125 (4)	0.743002 (10)	0.03300 (5)
C110	0.85923 (10)	0.3415 (4)	0.56576 (10)	0.0227 (3)
H10A	0.8598	0.2002	0.5276	0.027*
H10B	0.8462	0.2420	0.6094	0.027*
C111	0.94926 (11)	0.4793 (5)	0.57678 (11)	0.0309 (4)
H11A	0.9636	0.5703	0.5330	0.046*
H11B	0.9920	0.3342	0.5900	0.046*
H11C	0.9490	0.6204	0.6143	0.046*
C112	0.56356 (11)	1.1641 (4)	0.43874 (10)	0.0244 (4)
H12A	0.5351	1.2060	0.3924	0.037*
H12B	0.5883	1.3373	0.4595	0.037*
H12C	0.5216	1.0872	0.4694	0.037*
C113	0.84686 (11)	0.3415 (4)	0.39530 (11)	0.0278 (4)
H13A	0.8299	0.1480	0.4056	0.042*
H13B	0.8989	0.3903	0.4246	0.042*
H13C	0.8580	0.3568	0.3455	0.042*
C21	0.65996 (11)	0.8775 (4)	−0.03465 (10)	0.0229 (3)
C22	0.67743 (11)	0.7110 (4)	−0.09374 (10)	0.0273 (4)
H22	0.6382	0.7165	−0.1342	0.033*
C23	0.75171 (11)	0.5350 (5)	−0.09496 (10)	0.0290 (4)
H23	0.7606	0.4308	−0.1363	0.035*
C24	0.81179 (10)	0.5126 (4)	−0.03648 (9)	0.0245 (3)
C24A	0.79602 (11)	0.6781 (3)	0.02431 (10)	0.0210 (3)
C24B	0.84379 (10)	0.7101 (4)	0.09345 (9)	0.0214 (3)
C25	0.92166 (11)	0.5920 (4)	0.12524 (10)	0.0237 (3)
H25	0.9541	0.4601	0.1008	0.028*
C26	0.94839 (11)	0.6785 (4)	0.19408 (11)	0.0278 (4)
Br21	1.054315 (12)	0.52725 (4)	0.238642 (11)	0.03635 (6)
C27	0.90157 (12)	0.8735 (5)	0.23248 (11)	0.0298 (4)
H27	0.9219	0.9246	0.2789	0.036*
C28	0.82479 (11)	0.9922 (4)	0.20191 (10)	0.0275 (4)
H28	0.7927	1.1223	0.2272	0.033*
C28A	0.79715 (11)	0.9106 (4)	0.13222 (10)	0.0226 (3)
N29	0.72428 (9)	1.0030 (3)	0.09020 (8)	0.0230 (3)
C29A	0.72183 (11)	0.8599 (4)	0.02435 (9)	0.0212 (3)
C210	0.66349 (11)	1.2114 (4)	0.11622 (10)	0.0260 (3)
H20A	0.6348	1.3127	0.0756	0.031*
H20B	0.6958	1.3514	0.1462	0.031*
C211	0.59423 (13)	1.0716 (6)	0.15941 (12)	0.0386 (5)
H21A	0.5573	0.9507	0.1284	0.058*
H21B	0.5594	1.2182	0.1796	0.058*
H21C	0.6223	0.9578	0.1973	0.058*
C212	0.89124 (12)	0.3248 (4)	−0.03838 (11)	0.0315 (4)
H22A	0.8897	0.2257	−0.0836	0.047*
H22B	0.8918	0.1871	0.0000	0.047*
H22C	0.9430	0.4413	−0.0328	0.047*
C213	0.57866 (11)	1.0603 (5)	−0.03923 (10)	0.0299 (4)
H23A	0.5946	1.2589	−0.0434	0.045*
H23B	0.5481	1.0339	0.0033	0.045*
H23C	0.5415	1.0048	−0.0806	0.045*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C11	0.0206 (6)	0.0192 (7)	0.0240 (8)	−0.0013 (6)	0.0023 (6)	−0.0019 (7)
C12	0.0276 (8)	0.0290 (9)	0.0194 (8)	−0.0017 (6)	0.0013 (7)	−0.0033 (7)
C13	0.0260 (8)	0.0304 (9)	0.0192 (8)	0.0010 (7)	−0.0022 (6)	0.0005 (7)
C14	0.0202 (7)	0.0175 (7)	0.0232 (8)	0.0001 (5)	−0.0008 (6)	0.0020 (6)
C14A	0.0162 (6)	0.0179 (7)	0.0188 (8)	−0.0028 (5)	0.0002 (6)	0.0000 (6)
C14B	0.0166 (7)	0.0182 (8)	0.0213 (8)	−0.0041 (5)	0.0001 (6)	0.0007 (6)
C15	0.0195 (6)	0.0203 (8)	0.0228 (8)	−0.0027 (6)	0.0014 (6)	−0.0016 (7)
C16	0.0230 (7)	0.0269 (8)	0.0221 (8)	−0.0059 (7)	0.0055 (6)	−0.0048 (8)
C17	0.0243 (8)	0.0323 (9)	0.0203 (8)	−0.0072 (7)	0.0017 (6)	0.0000 (7)
C18	0.0225 (7)	0.0255 (9)	0.0219 (8)	−0.0030 (6)	−0.0019 (6)	0.0036 (7)
C18A	0.0170 (6)	0.0176 (8)	0.0213 (8)	−0.0036 (5)	0.0003 (5)	0.0018 (6)
N19	0.0187 (5)	0.0206 (7)	0.0198 (7)	0.0007 (5)	−0.0011 (5)	−0.0005 (6)
C19A	0.0163 (7)	0.0175 (7)	0.0212 (8)	−0.0030 (5)	−0.0016 (6)	−0.0002 (6)
Br11	0.03198 (9)	0.04153 (11)	0.02647 (9)	0.00080 (8)	0.00871 (7)	−0.00781 (9)
C110	0.0212 (7)	0.0201 (7)	0.0264 (9)	0.0013 (6)	−0.0016 (6)	0.0013 (7)
C111	0.0196 (7)	0.0412 (11)	0.0316 (10)	−0.0008 (7)	−0.0011 (7)	−0.0035 (9)
C112	0.0215 (7)	0.0258 (9)	0.0258 (9)	0.0025 (6)	0.0008 (7)	0.0023 (7)
C113	0.0267 (8)	0.0278 (8)	0.0290 (10)	0.0030 (7)	0.0038 (7)	−0.0071 (8)
C21	0.0227 (8)	0.0252 (9)	0.0209 (8)	−0.0028 (6)	0.0019 (6)	0.0055 (7)
C22	0.0270 (8)	0.0320 (10)	0.0222 (8)	−0.0051 (8)	−0.0013 (6)	0.0019 (8)
C23	0.0331 (9)	0.0327 (10)	0.0215 (8)	−0.0041 (9)	0.0041 (7)	−0.0045 (9)
C24	0.0261 (7)	0.0231 (8)	0.0248 (8)	−0.0030 (7)	0.0052 (6)	0.0006 (7)
C24A	0.0215 (7)	0.0213 (9)	0.0205 (8)	−0.0029 (6)	0.0026 (6)	0.0025 (6)
C24B	0.0208 (7)	0.0209 (8)	0.0225 (8)	−0.0023 (6)	0.0021 (6)	0.0018 (7)
C25	0.0224 (7)	0.0261 (9)	0.0225 (8)	−0.0003 (6)	0.0016 (6)	0.0031 (7)
C26	0.0220 (7)	0.0328 (10)	0.0280 (9)	−0.0011 (6)	−0.0031 (7)	0.0059 (7)
Br21	0.02796 (8)	0.04670 (12)	0.03295 (11)	0.00446 (8)	−0.00746 (7)	0.00629 (9)
C27	0.0297 (9)	0.0371 (11)	0.0220 (9)	−0.0045 (7)	−0.0014 (7)	−0.0020 (8)
C28	0.0286 (8)	0.0295 (10)	0.0242 (9)	−0.0011 (7)	0.0005 (7)	−0.0042 (8)
C28A	0.0213 (7)	0.0239 (8)	0.0224 (8)	−0.0021 (6)	0.0006 (6)	0.0007 (7)
N29	0.0230 (6)	0.0236 (7)	0.0221 (7)	0.0005 (6)	0.0000 (5)	−0.0008 (6)
C29A	0.0225 (7)	0.0218 (8)	0.0195 (8)	−0.0042 (6)	0.0027 (6)	0.0031 (6)
C210	0.0243 (7)	0.0267 (9)	0.0273 (9)	0.0009 (7)	0.0041 (6)	−0.0024 (8)
C211	0.0307 (9)	0.0550 (14)	0.0310 (10)	0.0015 (9)	0.0085 (8)	0.0063 (10)
C212	0.0312 (9)	0.0339 (10)	0.0297 (10)	0.0038 (7)	0.0053 (8)	−0.0062 (8)
C213	0.0250 (8)	0.0363 (10)	0.0280 (9)	−0.0003 (7)	−0.0007 (7)	0.0044 (8)

Geometric parameters (Å, º)

C11—C12	1.385 (2)	C21—C22	1.390 (3)
C11—C19A	1.403 (2)	C21—C29A	1.401 (2)
C11—C113	1.508 (2)	C21—C213	1.505 (2)
C12—C13	1.393 (3)	C22—C23	1.403 (3)
C12—H12	0.9300	C22—H22	0.9300
C13—C14	1.389 (2)	C23—C24	1.379 (2)
C13—H13	0.9300	C23—H23	0.9300
C14—C14A	1.397 (2)	C24—C24A	1.407 (3)
C14—C112	1.501 (2)	C24—C212	1.501 (2)
C14A—C19A	1.429 (2)	C24A—C29A	1.417 (2)
C14A—C14B	1.450 (2)	C24A—C24B	1.443 (2)
C14B—C15	1.394 (2)	C24B—C25	1.405 (2)
C14B—C18A	1.411 (2)	C24B—C28A	1.408 (2)
C15—C16	1.387 (2)	C25—C26	1.379 (3)
C15—H15	0.9300	C25—H25	0.9300
C16—C17	1.397 (3)	C26—C27	1.388 (3)
C16—Br11	1.9025 (17)	C26—Br21	1.9029 (18)
C17—C18	1.383 (2)	C27—C28	1.384 (3)
C17—H17	0.9300	C27—H27	0.9300
C18—C18A	1.397 (2)	C28—C28A	1.391 (3)
C18—H18	0.9300	C28—H28	0.9300
C18A—N19	1.381 (2)	C28A—N29	1.384 (2)
N19—C19A	1.393 (2)	N29—C29A	1.396 (2)
N19—C110	1.459 (2)	N29—C210	1.453 (2)
C110—C111	1.521 (2)	C210—C211	1.525 (3)
C110—H10A	0.9700	C210—H20A	0.9700
C110—H10B	0.9700	C210—H20B	0.9700
C111—H11A	0.9600	C211—H21A	0.9600
C111—H11B	0.9600	C211—H21B	0.9600
C111—H11C	0.9600	C211—H21C	0.9600
C112—H12A	0.9600	C212—H22A	0.9600
C112—H12B	0.9600	C212—H22B	0.9600
C112—H12C	0.9600	C212—H22C	0.9600
C113—H13A	0.9600	C213—H23A	0.9600
C113—H13B	0.9600	C213—H23B	0.9600
C113—H13C	0.9600	C213—H23C	0.9600
C12—C11—C19A	115.58 (15)	C22—C21—C29A	115.62 (16)
C12—C11—C113	118.73 (16)	C22—C21—C213	118.47 (16)
C19A—C11—C113	125.70 (16)	C29A—C21—C213	125.90 (17)
C11—C12—C13	123.42 (17)	C21—C22—C23	122.82 (17)
C11—C12—H12	118.3	C21—C22—H22	118.6
C13—C12—H12	118.3	C23—C22—H22	118.6
C14—C13—C12	121.55 (17)	C24—C23—C22	121.73 (18)
C14—C13—H13	119.2	C24—C23—H23	119.1
C12—C13—H13	119.2	C22—C23—H23	119.1
C13—C14—C14A	116.82 (15)	C23—C24—C24A	116.91 (17)
C13—C14—C112	120.58 (16)	C23—C24—C212	121.37 (17)
C14A—C14—C112	122.59 (16)	C24A—C24—C212	121.71 (16)
C14—C14A—C19A	121.00 (15)	C24—C24A—C29A	120.85 (16)
C14—C14A—C14B	132.50 (15)	C24—C24A—C24B	132.18 (16)
C19A—C14A—C14B	106.48 (14)	C29A—C24A—C24B	106.96 (15)
C15—C14B—C18A	119.62 (16)	C25—C24B—C28A	119.32 (16)
C15—C14B—C14A	133.79 (15)	C25—C24B—C24A	134.11 (16)
C18A—C14B—C14A	106.58 (14)	C28A—C24B—C24A	106.55 (14)
C16—C15—C14B	117.74 (16)	C26—C25—C24B	117.62 (16)
C16—C15—H15	121.1	C26—C25—H25	121.2
C14B—C15—H15	121.1	C24B—C25—H25	121.2
C15—C16—C17	122.65 (16)	C25—C26—C27	122.85 (17)
C15—C16—Br11	119.15 (13)	C25—C26—Br21	118.95 (14)
C17—C16—Br11	118.17 (13)	C27—C26—Br21	118.19 (14)
C18—C17—C16	120.17 (17)	C28—C27—C26	120.25 (18)
C18—C17—H17	119.9	C28—C27—H27	119.9
C16—C17—H17	119.9	C26—C27—H27	119.9
C17—C18—C18A	117.80 (16)	C27—C28—C28A	117.89 (17)
C17—C18—H18	121.1	C27—C28—H28	121.1
C18A—C18—H18	121.1	C28A—C28—H28	121.1
N19—C18A—C18	128.48 (15)	N29—C28A—C28	128.49 (16)
N19—C18A—C14B	109.54 (14)	N29—C28A—C24B	109.46 (15)
C18—C18A—C14B	121.98 (15)	C28—C28A—C24B	122.05 (16)
C18A—N19—C19A	108.97 (13)	C28A—N29—C29A	108.61 (14)
C18A—N19—C110	121.91 (14)	C28A—N29—C210	121.85 (15)
C19A—N19—C110	129.09 (15)	C29A—N29—C210	129.53 (14)
N19—C19A—C11	130.01 (15)	N29—C29A—C21	129.56 (16)
N19—C19A—C14A	108.42 (15)	N29—C29A—C24A	108.40 (15)
C11—C19A—C14A	121.57 (15)	C21—C29A—C24A	122.04 (17)
N19—C110—C111	112.29 (15)	N29—C210—C211	112.37 (17)
N19—C110—H10A	109.1	N29—C210—H20A	109.1
C111—C110—H10A	109.1	C211—C210—H20A	109.1
N19—C110—H10B	109.1	N29—C210—H20B	109.1
C111—C110—H10B	109.1	C211—C210—H20B	109.1
H10A—C110—H10B	107.9	H20A—C210—H20B	107.9
C110—C111—H11A	109.5	C210—C211—H21A	109.5
C110—C111—H11B	109.5	C210—C211—H21B	109.5
H11A—C111—H11B	109.5	H21A—C211—H21B	109.5
C110—C111—H11C	109.5	C210—C211—H21C	109.5
H11A—C111—H11C	109.5	H21A—C211—H21C	109.5
H11B—C111—H11C	109.5	H21B—C211—H21C	109.5
C14—C112—H12A	109.5	C24—C212—H22A	109.5
C14—C112—H12B	109.5	C24—C212—H22B	109.5
H12A—C112—H12B	109.5	H22A—C212—H22B	109.5
C14—C112—H12C	109.5	C24—C212—H22C	109.5
H12A—C112—H12C	109.5	H22A—C212—H22C	109.5
H12B—C112—H12C	109.5	H22B—C212—H22C	109.5
C11—C113—H13A	109.5	C21—C213—H23A	109.5
C11—C113—H13B	109.5	C21—C213—H23B	109.5
H13A—C113—H13B	109.5	H23A—C213—H23B	109.5
C11—C113—H13C	109.5	C21—C213—H23C	109.5
H13A—C113—H13C	109.5	H23A—C213—H23C	109.5
H13B—C113—H13C	109.5	H23B—C213—H23C	109.5