Crystal structure of 4,4-di­bromo-1-(3,4-di­meth­oxy­phen­yl)-2-aza­buta-1,3-diene-1-carbo­nitrile

Chaabene, M.; Khatyr, A.; Knorr, M.; Askri, M.; Rousselin, Y.; Kubicki, M.M.

doi:10.1107/S2056989016011075

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ISSN: 2056-9890

Volume 72| Part 8| August 2016| Pages 1167-1170

https://doi.org/10.1107/S2056989016011075

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Crystal structure of 4,4-dibromo-1-(3,4-dimethoxyphenyl)-2-azabuta-1,3-diene-1-carbonitrile

Marwa Chaabene,^a Abderrahim Khatyr,^b Michael Knorr,^b ^* Moheddine Askri,^a Yoann Rousselin ^c and Marek M. Kubicki ^c ^*

^aLaboratoire de Chimie Hétérocyclique, Produits Naturels et Réactivité (LR11ES39), Département de Chimie, Faculté des Sciences de Monastir, Tunisia, ^bInstitut UTINAM UMR CNRS 6213, University of Franche-Comté, 16 route de Gray, 25030 Besançon, France, and ^cICMUB UMR CNRS 6302, University of Bourgogne, 9 avenue Alain Savary, 21078 Dijon, France
^*Correspondence e-mail: michael.knorr@univ-fcomte.fr, marek.kubicki@u-bourgogne.fr

Edited by S. Parkin, University of Kentucky, USA (Received 11 June 2016; accepted 7 July 2016; online 22 July 2016)

The title compound, C₁₂H₁₀Br₂N₂O₂, represents an example of a planar π-conjugated 2-azabutadiene molecule, which is both an interesting starting material for further organic transformations and a potential ligand in organometallic coordination chemistry. Its metric molecular parameters are typical for the family of 2-azabuta-1,3-dienes not substituted at the (CH) 3-position. In the crystal, the almost planar (r.m.s. deviation = 0.0658 Å) azadiene molecules form one-dimensional double-wide ribbons through intermolecular halogen bonds (C—Br⋯O and C—Br⋯Br—C), which then stack in a slipped manner through weak C—H⋯Br and π–π interactions to generate a three-dimensional network.

Keywords: crystal structure; substituted 2-azabuta-1,3-diene; weak hydrogen bonding; halogen bonding; π–π interactions.

CCDC reference: 1491488

1. Chemical context

In the context of our interest in developing novel π-conjugated dithioether compounds as ligands for coordination chemistry and further organic transformations, we have reported on the synthesis and crystal structure of 4,4-dichloro-1,1-diphenyl-2-azabuta-1,3-diene [Ph₂C=N—C(H)=CCl₂] and its conversion to [Ph₂C=N—C(H)=C(SR)₂] and [Ph₂C=N—C(H)=C(OPh)₂] by reaction with thiolates NaSR or NaOPh, respectively (Jacquot et al., 1999 , 2000 ; Jacquot-Rousseau et al., 2006 ; Kinghat et al., 2016 ). Several crystal structures of these molecules/ligands and their derived transition metal complexes reveal that despite the overall planarity of the π-conjugated chain, one aryl group of the –N=CPh₂ imine segment is tilted with respect to the azabutadienic array (Jacquot et al., 1999; Knorr et al., 2003 ; Kinghat et al., 2008 ). To circumvent this feature and to modulate the stereoelectronic properties, we examined other synthetic strategies for the synthesis of 2-azabutadienes. Intrigued by a communication briefly mentioning the formation of the nitrile-functionalized compounds [Ph(C≡N)C=N—C(H)=CX₂] (X = Cl or Br) by treatment of the α-aminonitrile H₂NCHPhC≡N with chloral or bromal (Sato & Adachi, 1978 ), we reinvestigated this reaction to explore the scope for the synthesis of other derivatives. For example, we succeeded in preparing the title compound [C₆H₃(OMe)₂(C≡N)C=N—C(H)=CBr₂], (1), bearing two electron-donating methoxy groups at the meta- and para-positions of the aryl ring (see Fig. 1).

Figure 1
The reaction scheme for the synthesis of (1).

2. Structural commentary

Compound (1) crystallizes from acetonitrile in the triclinic crystal system, space group P $[\overline{1}]$ . The transoid conformation of the azabutadiene chain found in [Ph₂C=N—C(H)=CCl₂] (Jacquot et al., 1999) is also observed in the crystal structure of (1) (Fig. 2). The azadiene chain (C9/N1/C11/C12) is essentially planar (r.m.s. deviation = 0.014 Å). The torsion angle C12—C11—N1—C9 is 177.9 (3)°. The aryl ring, as well as the CN substituent, form part of the π-conjugated array. The length of the vinylic C11=C12 bond matches well with that of [Ph₂C=N—C(H)=CCl₂] [1.332 (4) versus 1.319 (3) Å]. We are not aware of any other structurally characterized azabutadienes bearing a Br₂C=C moiety. For other organic compounds containing this dibromovinyl unit, such as 2,2-dibromovinylthiophene and 2-(2,2-dibromovinyl)-1-methyl-1H-imidazole-4,5-dicarbonitrile, C=C distances of 1.335 (7) and 1.317 (3) Å have been reported (Clément et al., 2011 ; Lokaj et al., 2011 ). The C9=N1 bond length of the imine group is also comparable with that of [Ph₂C=N—C(H)=CCl₂] [1.288 (3) versus 1.293 (2) Å].

Figure 2
An displacement ellipsoid plot of (1) at the 50% probability level.

3. Supramolecular features

Each planar molecule of (1) is connected through halogen (Cavallo et al., 2016 ) bifurcated bonds C12—Br2⋯(O1,O2) to two neighbouring molecules to form a one-dimensional ribbon. The ribbon is further connected through another kind of side halogen bond (C12—Br1⋯Br1—C12) to other neighbouring molecules with the formation of roughly planar one-dimensional double-wide straight chains (Fig. 3 and Table 1). These chains then stack in a slipped manner through very weak C—H⋯Br interactions (Fig. 4 and Table 2) to generate a three-dimensional supramolecular network (Fig. 5). When projecting the structure down the direction perpendicular to the planes of the planar molecules of (1) (e.g. down from the top in Fig. 4), one sees an interesting overlap in a head-to-tail arrangement of zigzagging unsaturated chains that leads to the formation of π–π stacking interactions around the symmetry centres located at (0, $[1 \over 2]$ , $[1 \over 2]$ ) and ( $[1 \over 2]$ , $[1 \over 2]$ , $[1 \over 2]$ ). They consist of overlaps between the azadiene C=C and C=N double bonds and parts of the aryl rings. For clarity, these overlaps are shown separately in Figs. 6 and 7. The mean interatomic separation between the chains built around ( $[1 \over 2]$ , $[1 \over 2]$ , $[1 \over 2]$ ) (Fig. 6 and Table 3) is 3.523 (5) Å, while a slightly shorter separation of 3.464 (5) Å is observed for the second couple built around (0, $[1 \over 2]$ , $[1 \over 2]$ ) (Fig. 7 and Table 3).

Table 1
Halogen-bonding parameters (Å, °) for (1)

D	Br	A	D—Br	Br⋯A	D—Br⋯A
C12	Br2	O1ⁱ	1.878 (3)	3.185 (2)	124.26 (9)
C12	Br2	O2ⁱ	1.878 (3)	3.153 (2)	167.6 (1)
C12	Br1	Br1ⁱⁱ	1.872 (3)	3.4340 (5)	144.8 (1)
Symmetry codes: (i) x − 1, y, z − 1; (ii) −x + 1, −y + 2, −z + 1.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1A⋯Br1ⁱ	0.98	3.01	3.867 (4)	146
C1—H1B⋯Br2ⁱⁱ	0.98	3.04	3.869 (4)	143
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) -x, -y+1, -z+1.

Table 3
π–π interactions (Å) in (1)

Atom A	Atom B	A⋯B	Atom C	Atom D	C⋯D
C5	C12ⁱⁱ	3.445 (5)	C11	O1ⁱ	3.455 (4)
C6	C11ⁱⁱ	3.497 (5)	N1	C3ⁱ	3.556 (4)
C9	N1ⁱⁱ	3.451 (4)	C9	C8ⁱ	3.523 (5)
			C6	C7ⁱ	3.559 (5)
Symmetry codes: (i) 1 − x, 1 − y, 1 − z; (ii) −x, 1 − y, 1 − z.

Figure 3
Part of the crystal structure of (1), showing the formation of double-wide ribbons through halogen C—Br⋯O and C—Br⋯Br—C bonding. [Symmetry codes: (i) x − 1, y, z − 1; (ii) −x + 1, −y + 2, −z + 1.]

Figure 4
Part of the crystal structure of (1), showing the C—H⋯Br interactions. [Symmetry codes: (i) −x + 1, −y + 1, −z + 1; (ii) −x, −y + 1, −z + 1.]

Figure 5
Part of the three-dimensional packing in (1) projected down the [101] direction and showing the halogen and weak C–H⋯Br interactions detailed in Figs. 3

and 4

Figure 6
Part of the crystal structure of (1), showing the potential π–π interactions in two head-to-tail molecules overlapping around the symmetry centre at ( $[1 \over 2]$ , $[1 \over 2]$ , $[1 \over 2]$ ) (see also Fig. 4

). H atoms have been omitted for clarity. [Symmetry code: (i) −x + 1, −y + 1, −z + 1.]

Figure 7
Part of the crystal structure of (1), showing the potential π–π interactions in two head-to-tail molecules overlapping around the symmetry centre at (0, $[1 \over 2]$ , $[1 \over 2]$ ) (see also Fig. 4

). H atoms have been omitted for clarity. [Symmetry code: (ii) −x, −y + 1, −z + 1.]

4. Database survey

There are several other examples of structurally characterized 2-azabutadienes bearing cyano (nitrile) substituents attached at the azabutadienic array. These include 3-cyano-4-(n-methoxyphenyl)-1,1-diphenyl-2-aza-1,3-butadienes (n = 2, 3 or 4), 3-cyano-4-(4-cyanophenyl)-1,1-diphenyl-2-aza-1,3-butadiene, 3-cyano-4-(2,4-dimethoxyphenyl)-1,1-diphenyl-2-aza-1,3-butadiene, 3-cyano-4-(2,4-dichlorophenyl)-1,1-diphenyl-2-aza-1,3-butadiene and 3-cyano-4-(n-fluorophenyl)-1,1-diphenyl-2-aza-1,3-butadienes (n = 2 or 4) (Angelova et al., 1993a ,b ; Macícek et al., 1993a ,b ; Dryanska et al., 1995 ). Furthermore, the structure of (E)-4,4-dicyano-3-methylthio-1-phenyl-1-(1-pyrrolidinyl)-2-azabuta-1,3-diene has been reported (Lorente et al., 1996 ). Note that in all these structures there is a significant deviation from linearity of the C=N—C=C chain. This feature is due to the presence of a substituent at the 3-C position of the 2-azabuta-1,3-diene chain. We also observed and discussed this feature in the structures of [Ar₂C=N—C(S^tBu)=C(H)S^tBu] (Kinghat et al., 2016).

5. Synthesis and crystallization

The required α-aminonitrile used a starting material was obtained according a literature protocol (Mai & Patil, 1984 ). An equimolar mixture of N-(dibromoethylenyl)-1-imino-1-vertracetonitrile (10 mmol) and tribromoacetaldehyde in 10 ml of acetonitrile was stirred under reflux for 2 h. The solution was then filtered and all volatiles removed under reduced pressure. The crude residue was recrystallized from acetonitrile affording clear-light orange crystals (yield 79%; m.p. 440 K; ¹H RMN (CDCl₃, 300 MHz): δ 3.95 (s, 3H, OCH₃), 3.96 (s, 3H, OCH₃), 6.93 (d, 1H, J = 9 Hz, 1 Ar-H), 7.65 (s, 2H, 2 Ar-H), 8.04 (s, 1H, =CH); ¹³C{¹H} NMR (CDCl₃, 75 MHz): δ 55.9 (OCH₃), 56.2 (OCH₃), 103.2 (=CBr₂), 110.6 (C≡N), 124.3–153.9 (C_Ar), 137.8 (C=N), 142.2 (CH); λ_max = 245 nm (e = 3300 M⁻¹ cm⁻¹), λ_max = 353 nm (e = 7580 M⁻¹ cm⁻¹); IR (ATR) cm⁻¹: 2219 (C≡N), 1597 (C=N), 1569 (C=C).

6. Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 4. All H atoms were placed in calculated positions and treated in a riding model. C—H distances were set at 0.95 (aromatic) and 0.98 Å (methyl), with U_iso(H) = xU_eq(C), where x = 1.5 for idealized methyl H atoms refined as rotating groups and 1.2 for all other H atoms.

Table 4
Experimental details

Crystal data
Chemical formula	C₁₂H₁₀Br₂N₂O₂
M_r	374.04
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	100
a, b, c (Å)	7.6878 (4), 9.2782 (5), 10.8111 (6)
α, β, γ (°)	106.162 (2), 100.887 (2), 110.009 (2)
V (Å³)	660.57 (6)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	6.13
Crystal size (mm)	0.25 × 0.2 × 0.1

Data collection
Diffractometer	Bruker D8 VENTURE
Absorption correction	Multi-scan (SADABS; Bruker, 2014 )
T_min, T_max	0.537, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	23955, 3045, 2442
R_int	0.067
(sin θ/λ)_max (Å⁻¹)	0.652

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.027, 0.067, 1.03
No. of reflections	3045
No. of parameters	165
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.80, −0.42
Computer programs: APEX2 and SAINT (Bruker, 2013 ), SHELXT (Sheldrick, 2015a ), SHELXL2014 (Sheldrick, 2015b ) and OLEX2 (Dolomanov et al., 2009 ).

Supporting information

CCDC reference: 1491488

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989016011075/pk2582sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989016011075/pk2582Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989016011075/pk2582Isup3.cml

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

4,4-Dibromo-1-(3,4-dimethoxyphenyl)-2-azabuta-1,3-diene-1-carbonitrile top

Crystal data top

C₁₂H₁₀Br₂N₂O₂	Z = 2
M_r = 374.04	F(000) = 364
Triclinic, P1	D_x = 1.881 Mg m⁻³
a = 7.6878 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.2782 (5) Å	Cell parameters from 8732 reflections
c = 10.8111 (6) Å	θ = 3.0–27.5°
α = 106.162 (2)°	µ = 6.13 mm⁻¹
β = 100.887 (2)°	T = 100 K
γ = 110.009 (2)°	Plqte, clear light orange
V = 660.57 (6) Å³	0.25 × 0.2 × 0.1 mm

Data collection top

Bruker D8 VENTURE diffractometer	3045 independent reflections
Radiation source: X-ray tube, Siemens KFF Mo 2K-90C	2442 reflections with I > 2σ(I)
TRIUMPH curved crystal monochromator	R_int = 0.067
φ and ω scans'	θ_max = 27.6°, θ_min = 3.0°
Absorption correction: multi-scan (SADABS; Bruker, 2014)	h = −9→10
T_min = 0.537, T_max = 0.746	k = −12→12
23955 measured reflections	l = −14→14

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.027	H-atom parameters constrained
wR(F²) = 0.067	w = 1/[σ²(F_o²) + (0.0307P)² + 0.5386P] where P = (F_o² + 2F_c²)/3
S = 1.03	(Δ/σ)_max = 0.001
3045 reflections	Δρ_max = 0.80 e Å⁻³
165 parameters	Δρ_min = −0.42 e Å⁻³
0 restraints

Special details top

Experimental. Absorption correction: SADABS-2014/4 (Bruker,2014) was used for absorption correction. wR2(int) was 0.0938 before and 0.0647 after correction. The Ratio of minimum to maximum transmission is 0.7197. The λ/2 correction factor is 0.00150.

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.5229 (4)	0.2556 (4)	0.9031 (3)	0.0198 (6)
H1A	0.5402	0.1716	0.8346	0.030*
H1B	0.3876	0.2129	0.9037	0.030*
H1C	0.6109	0.2824	0.9927	0.030*
C2	0.6815 (5)	0.8341 (4)	0.8299 (3)	0.0246 (7)
H2A	0.7114	0.8389	0.7465	0.037*
H2B	0.7909	0.9196	0.9088	0.037*
H2C	0.5636	0.8527	0.8307	0.037*
C3	0.4518 (4)	0.3908 (3)	0.7558 (3)	0.0163 (6)
C4	0.3008 (4)	0.2473 (3)	0.6590 (3)	0.0160 (6)
H4	0.2729	0.1450	0.6709	0.019*
C5	0.1904 (4)	0.2535 (3)	0.5444 (3)	0.0156 (6)
H5	0.0857	0.1552	0.4792	0.019*
C6	0.2308 (4)	0.4007 (3)	0.5242 (3)	0.0149 (5)
C7	0.3852 (4)	0.5476 (3)	0.6221 (3)	0.0154 (6)
H7	0.4130	0.6496	0.6096	0.019*
C8	0.4946 (4)	0.5419 (3)	0.7352 (3)	0.0149 (5)
C9	0.1186 (4)	0.4092 (3)	0.4029 (3)	0.0148 (5)
C10	−0.0396 (4)	0.2543 (4)	0.3038 (3)	0.0210 (6)
C11	0.0555 (4)	0.5495 (3)	0.2655 (3)	0.0175 (6)
H11	−0.0400	0.4495	0.1958	0.021*
C12	0.0911 (4)	0.6927 (3)	0.2490 (3)	0.0139 (5)
N1	0.1576 (3)	0.5463 (3)	0.3839 (2)	0.0145 (5)
N2	−0.1661 (4)	0.1374 (3)	0.2229 (3)	0.0356 (7)
O1	0.5666 (3)	0.4013 (2)	0.8715 (2)	0.0195 (4)
O2	0.6500 (3)	0.6752 (2)	0.8351 (2)	0.0195 (4)
Br1	0.27146 (4)	0.89631 (3)	0.38235 (3)	0.01976 (9)
Br2	−0.04365 (4)	0.69810 (3)	0.08743 (3)	0.01900 (9)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0209 (14)	0.0221 (14)	0.0233 (16)	0.0103 (12)	0.0097 (12)	0.0148 (13)
C2	0.0258 (16)	0.0142 (14)	0.0254 (17)	0.0023 (12)	0.0012 (13)	0.0074 (13)
C3	0.0145 (13)	0.0177 (14)	0.0202 (15)	0.0082 (11)	0.0082 (11)	0.0086 (12)
C4	0.0180 (14)	0.0152 (13)	0.0194 (15)	0.0087 (11)	0.0095 (12)	0.0083 (11)
C5	0.0121 (13)	0.0167 (13)	0.0147 (14)	0.0043 (11)	0.0038 (11)	0.0035 (11)
C6	0.0142 (12)	0.0161 (13)	0.0146 (14)	0.0071 (10)	0.0062 (11)	0.0038 (11)
C7	0.0168 (13)	0.0137 (13)	0.0144 (14)	0.0050 (11)	0.0058 (11)	0.0044 (11)
C8	0.0132 (13)	0.0142 (13)	0.0152 (14)	0.0039 (10)	0.0046 (11)	0.0048 (11)
C9	0.0133 (13)	0.0151 (13)	0.0146 (14)	0.0061 (10)	0.0055 (11)	0.0025 (11)
C10	0.0226 (15)	0.0186 (14)	0.0217 (16)	0.0076 (13)	0.0050 (13)	0.0099 (13)
C11	0.0171 (14)	0.0170 (14)	0.0141 (14)	0.0069 (11)	0.0033 (11)	0.0012 (11)
C12	0.0133 (12)	0.0179 (13)	0.0104 (13)	0.0064 (11)	0.0042 (11)	0.0053 (11)
N1	0.0157 (11)	0.0160 (11)	0.0117 (12)	0.0072 (9)	0.0049 (9)	0.0038 (9)
N2	0.0337 (16)	0.0205 (14)	0.0371 (18)	0.0036 (12)	−0.0042 (14)	0.0087 (13)
O1	0.0191 (10)	0.0185 (10)	0.0202 (11)	0.0059 (8)	0.0025 (8)	0.0110 (9)
O2	0.0203 (10)	0.0130 (9)	0.0174 (11)	0.0017 (8)	−0.0006 (8)	0.0053 (8)
Br1	0.02102 (15)	0.01428 (14)	0.01661 (16)	0.00322 (11)	0.00125 (12)	0.00357 (11)
Br2	0.02026 (15)	0.02270 (16)	0.01424 (16)	0.01035 (12)	0.00265 (12)	0.00730 (12)

Geometric parameters (Å, º) top

C1—H1A	0.9800	C5—C6	1.383 (4)
C1—H1B	0.9800	C6—C7	1.415 (4)
C1—H1C	0.9800	C6—C9	1.464 (4)
C1—O1	1.431 (3)	C7—H7	0.9500
C2—H2A	0.9800	C7—C8	1.372 (4)
C2—H2B	0.9800	C8—O2	1.372 (3)
C2—H2C	0.9800	C9—C10	1.465 (4)
C2—O2	1.430 (3)	C9—N1	1.288 (3)
C3—C4	1.387 (4)	C10—N2	1.147 (4)
C3—C8	1.418 (4)	C11—H11	0.9500
C3—O1	1.345 (3)	C11—C12	1.332 (4)
C4—H4	0.9500	C11—N1	1.384 (4)
C4—C5	1.391 (4)	C12—Br1	1.872 (3)
C5—H5	0.9500	C12—Br2	1.878 (3)

H1A—C1—H1B	109.5	C5—C6—C9	121.7 (2)
H1A—C1—H1C	109.5	C7—C6—C9	118.7 (2)
H1B—C1—H1C	109.5	C6—C7—H7	120.2
O1—C1—H1A	109.5	C8—C7—C6	119.6 (3)
O1—C1—H1B	109.5	C8—C7—H7	120.2
O1—C1—H1C	109.5	C7—C8—C3	120.5 (3)
H2A—C2—H2B	109.5	O2—C8—C3	114.7 (2)
H2A—C2—H2C	109.5	O2—C8—C7	124.8 (2)
H2B—C2—H2C	109.5	C6—C9—C10	117.0 (2)
O2—C2—H2A	109.5	N1—C9—C6	121.6 (2)
O2—C2—H2B	109.5	N1—C9—C10	121.5 (3)
O2—C2—H2C	109.5	N2—C10—C9	176.7 (3)
C4—C3—C8	119.4 (3)	C12—C11—H11	120.0
O1—C3—C4	125.4 (3)	C12—C11—N1	120.0 (3)
O1—C3—C8	115.1 (2)	N1—C11—H11	120.0
C3—C4—H4	120.1	C11—C12—Br1	123.0 (2)
C3—C4—C5	119.8 (3)	C11—C12—Br2	120.4 (2)
C5—C4—H4	120.1	Br1—C12—Br2	116.65 (14)
C4—C5—H5	119.5	C9—N1—C11	120.4 (2)
C6—C5—C4	120.9 (3)	C3—O1—C1	118.0 (2)
C6—C5—H5	119.5	C8—O2—C2	116.8 (2)
C5—C6—C7	119.6 (3)

C3—C4—C5—C6	1.1 (4)	C7—C6—C9—C10	179.8 (2)
C3—C8—O2—C2	−171.0 (2)	C7—C6—C9—N1	0.0 (4)
C4—C3—C8—C7	1.5 (4)	C7—C8—O2—C2	9.3 (4)
C4—C3—C8—O2	−178.2 (2)	C8—C3—C4—C5	−1.4 (4)
C4—C3—O1—C1	−4.4 (4)	C8—C3—O1—C1	175.8 (2)
C4—C5—C6—C7	−0.7 (4)	C9—C6—C7—C8	−178.7 (2)
C4—C5—C6—C9	178.7 (3)	C10—C9—N1—C11	−2.9 (4)
C5—C6—C7—C8	0.8 (4)	C12—C11—N1—C9	177.2 (3)
C5—C6—C9—C10	0.3 (4)	N1—C11—C12—Br1	−1.7 (4)
C5—C6—C9—N1	−179.5 (3)	N1—C11—C12—Br2	179.0 (2)
C6—C7—C8—C3	−1.2 (4)	O1—C3—C4—C5	178.8 (3)
C6—C7—C8—O2	178.5 (2)	O1—C3—C8—C7	−178.7 (3)
C6—C9—N1—C11	176.9 (2)	O1—C3—C8—O2	1.5 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1A···Br1ⁱ	0.98	3.01	3.867 (4)	146
C1—H1B···Br2ⁱⁱ	0.98	3.04	3.869 (4)	143

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x, −y+1, −z+1.

Halogen-bonding parameters (Å, °) for (1). top

D	Br	A	D—Br	Br···A	D—Br···A
C12	Br2	O1ⁱ	1.878 (3)	3.185 (2)	124.26 (9)
C12	Br2	O2ⁱ	1.878 (3)	3.153 (2)	167.6 (1)
C12	Br1	Br1ⁱⁱ	1.872 (3)	3.4340 (5)	144.8 (1)

Symmetry codes: (i) x-1, y, z-1; (ii) -x+1, -y+2, -z+1.

π–π interactions (Å) in (1). top

Atom A	Atom B	Distance A···B	Atom C	Atom D	Distance C···D
C5	C12ⁱⁱ	3.445 (5)	C11	O1ⁱ	3.455 (4)
C6	C11ⁱⁱ	3.497 (5)	N1	C3ⁱ	3.556 (4)
C9	N1ⁱⁱ	3.451 (4)	C9	C8ⁱ	3.523 (5)
			C6	C7ⁱ	3.559 (5)

Symmetry codes: (i) 1-x, 1-y, 1-z; (ii) -x, 1-y, 1-z.

Acknowledgements

We are grateful to the Universities of Franche–Comté and Bourgogne and the CNRS for financial support.

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