2,4-Bis(4-bromo­phen­yl)-3-aza­bicyclo­[3.3.1]nonan-9-one

Parthiban, P.; Ramkumar, V.; Amirthaganesan, S.; Jeong, Y.T.

doi:10.1107/S1600536809017565

organic compounds

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ISSN: 2056-9890

Volume 65| Part 6| June 2009| Page o1356

doi:10.1107/S1600536809017565

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2,4-Bis(4-bromophenyl)-3-azabicyclo[3.3.1]nonan-9-one

P. Parthiban,^a V. Ramkumar,^b S. Amirthaganesan ^a and Yeon Tae Jeong ^a ^*

^aDivision of Image Science and Information Engineering, Pukyong National University, Busan 608 739, Republic of Korea, and ^bDepartment of Chemistry, IIT Madras, Chennai, TamilNadu, India
^*Correspondence e-mail: ytjeong@pknu.ac.kr

(Received 7 May 2009; accepted 11 May 2009; online 20 May 2009)

The title compound, C₂₀H₁₉Br₂NO, shows a chair–chair conformation for the azabicycle with an equatorial disposition of the 4-bromophenyl groups [dihedral angle between the aromatic rings = 16.48 (3)°]. In the crystal, a short Br⋯Br contact [3.520 (4) Å] occurs and the structure is further stabilized by N—H⋯O hydrogen bonds and C—H⋯O interactions.

Related literature

For general background to the biological properties of 3-azabicyclononanes, see: Jeyaraman & Avila (1981 ); Hardick et al. (1996 ); Barker et al. (2005 ). For different conformations for the azabicycle, see: Parthiban et al. (2008a ,b ,c ,d , 2009 ); Smith-Verdier et al. (1983 ); Padegimas & Kovacic (1972 ). For ring puckering analysis, see: Cremer & Pople (1975 ).

Experimental

Crystal data

C₂₀H₁₉Br₂NO
M_r = 449.18
Triclinic, $[P \overline 1]$
a = 6.9415 (3) Å
b = 10.4489 (4) Å
c = 13.2888 (5) Å
α = 101.542 (2)°
β = 100.391 (2)°
γ = 94.472 (2)°
V = 922.34 (6) Å³
Z = 2
Mo Kα radiation
μ = 4.40 mm⁻¹
T = 298 K
0.38 × 0.25 × 0.20 mm

Data collection

Bruker SMART APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker 1999 ) T_min = 0.280, T_max = 0.415
12376 measured reflections
4036 independent reflections
2805 reflections with I > 2σ(I)
R_int = 0.024

Refinement

R[F² > 2σ(F²)] = 0.038
wR(F²) = 0.089
S = 1.02
4036 reflections
221 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.85 e Å⁻³
Δρ_min = −0.92 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯O1ⁱ	0.80 (3)	2.42 (3)	3.191 (3)	162 (3)
C16—H16⋯O1ⁱⁱ	0.93	2.53	3.242 (3)	133
Symmetry codes: (i) x+1, y, z; (ii) -x, -y+1, -z+1.

Data collection: SMART (Bruker–Nonius, 2004 ); cell refinement: SAINT-Plus (Bruker–Nonius, 2004); data reduction: SAINT-Plus (Bruker–Nonius, 2004); 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).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809017565/hb2967sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809017565/hb2967Isup2.hkl

checkCIF report

Comment top

3-Azabicyclononanes are important class of heterocycles due to their broad spectrum of biological activities (Jeyaraman & Avila, 1981; Hardick et al., 1996; Barker et al., 2005). Owing to the diverse possibilities in conformations, viz., chair-chair (Parthiban et al., 2008a,b,c,d, 2009), chair-boat (Smith-Verdier et al., 1983) and boat-boat (Padegimas & Kovacic, 1972) for the azabicycle, the present crystal study was undertaken to explore the conformation, stereochemistry and bonding of the title compound, (I).

The analysis of torsion angles, asymmetry parameters and least-squares plane calculation of the title compound shows that the piperidine ring adopts near ideal chair conformation with the deviation of ring atoms N1 and C8 from the C1/C2/C6/C7 plane by 0.636 (3) and -0.730 (3) Å. respectively; the q2 and q3 are 0.057 (3)Å and -0.610 (3) Å. The total puckering amplitude, Q_T = 0.613 (3)Å and θ = 174.5 (3)°. (Cremer & Pople, 1975).

The cyclohexane ring deviates from the ideal chair conformation by the deviation of ring atoms C8 and C4 from the C2/C3/C5/C6 plane by -0.693 (4)Å and 0.547 (3) Å, respectively. Total puckering amplitude, Q_T = 0.546 (3) Å, q2 = 0.109 (4) Å, q3 = -0.535 (4)Å and θ =168.6 (4)° (Cremer & Pople, 1975).

Hence, the title compound C₂₀ H₁₉ Br₂ N O, exists in twin-chair conformation with equatorial orientation of 4-bromophenyl groups on the heterocycle and are orientated at an angle of 16.48 (3)° to each other. the torsion angle of C8—C2—C1—C9 and C8—C6—C7—C15 are -177.26 (3) and -178.37 (4) °, respectively.

An interesting feature of the crystal structure is a weak intermolecular Br···Br [3.520 (4) Å; symmetry code: 1 - x, 1 - y, - z] interaction which is shorter than the sum of the van der Waals radius of Br atoms. The crystal structure is further stabilized by N—H···O interaction and C—H···O interaction, where the oxygen atom bonds with both C18 and N1 forming a bifurcated bond (Table 1).

Related literature top

For general background to the biological properties of 3-azabicyclononanes, see: Jeyaraman & Avila (1981); Hardick et al. (1996); Barker et al. (2005). For different conformations for the azabicycle, see: Parthiban et al. (2008a,b,c,d, 2009); Smith-Verdier et al. (1983); Padegimas & Kovacic (1972). For ring puckering analysis, see: Cremer & Pople (1975).

Experimental top

To a warm solution of 0.075 mol ammonium acetate in 50 ml absolute ethanol, 0.1 mol of para-bromobenzaldehyde and 0.05 mol of cyclohexanone were added. The mixture was gently warmed on a hot plate with stirring till the yellow color formed during the mixing of the reactants and stirring is continued over night at room temparature. At the end, the white crude azabicyclic ketone was separated by filtration and washed with 1:5 ethanol-ether mixture. Colourless blocks of (I) were recrystallised from ethanol.

Computing details top

Data collection: SMART (Bruker–Nonius, 2004); cell refinement: SAINT-Plus (Bruker–Nonius, 2004); data reduction: SAINT-Plus (Bruker–Nonius, 2004); 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

	Fig. 1. The molecular sturcture of (I) with non-hydrogen atoms represented as 30% probability ellipsoids.
	Fig. 2. N—H···O interaction and Br—Br interactions (dashed lines) in the crystal of (I).

2,4-Bis(4-bromophenyl)-3-azabicyclo[3.3.1]nonan-9-one top

Crystal data top

C₂₀H₁₉Br₂NO	Z = 2
M_r = 449.18	F(000) = 448
Triclinic, P1	D_x = 1.617 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.9415 (3) Å	Cell parameters from 4458 reflections
b = 10.4489 (4) Å	θ = 2.3–23.7°
c = 13.2888 (5) Å	µ = 4.40 mm⁻¹
α = 101.542 (2)°	T = 298 K
β = 100.391 (2)°	Block, colourless
γ = 94.472 (2)°	0.38 × 0.25 × 0.20 mm
V = 922.34 (6) Å³

Data collection top

Bruker SMART CCD diffractometer	4036 independent reflections
Radiation source: fine-focus sealed tube	2805 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.024
ϕ and ω scans	θ_max = 28.3°, θ_min = 1.6°
Absorption correction: multi-scan (SADABS; Bruker 1999)	h = −9→9
T_min = 0.280, T_max = 0.415	k = −13→10
12376 measured reflections	l = −16→17

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.089	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	w = 1/[σ²(F_o²) + (0.0266P)² + 1.1237P] where P = (F_o² + 2F_c²)/3
4036 reflections	(Δ/σ)_max = 0.001
221 parameters	Δρ_max = 0.85 e Å⁻³
0 restraints	Δρ_min = −0.92 e Å⁻³

Crystal data top

C₂₀H₁₉Br₂NO	γ = 94.472 (2)°
M_r = 449.18	V = 922.34 (6) Å³
Triclinic, P1	Z = 2
a = 6.9415 (3) Å	Mo Kα radiation
b = 10.4489 (4) Å	µ = 4.40 mm⁻¹
c = 13.2888 (5) Å	T = 298 K
α = 101.542 (2)°	0.38 × 0.25 × 0.20 mm
β = 100.391 (2)°

Data collection top

Bruker SMART CCD diffractometer	4036 independent reflections
Absorption correction: multi-scan (SADABS; Bruker 1999)	2805 reflections with I > 2σ(I)
T_min = 0.280, T_max = 0.415	R_int = 0.024
12376 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.038	0 restraints
wR(F²) = 0.089	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	Δρ_max = 0.85 e Å⁻³
4036 reflections	Δρ_min = −0.92 e Å⁻³
221 parameters

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
Br1	0.51212 (7)	−0.32865 (4)	0.04459 (3)	0.07124 (16)
Br2	0.76344 (6)	0.92093 (4)	0.40986 (3)	0.06669 (15)
C1	0.2024 (4)	0.1542 (3)	0.2864 (2)	0.0314 (6)
H1	0.1988	0.1411	0.3571	0.038*
C2	−0.0130 (4)	0.1605 (3)	0.2300 (2)	0.0354 (7)
H2	−0.0943	0.0792	0.2291	0.043*
C3	−0.0360 (5)	0.1813 (3)	0.1177 (2)	0.0469 (8)
H3A	0.0242	0.1136	0.0771	0.056*
H3B	−0.1754	0.1706	0.0864	0.056*
C4	0.0554 (5)	0.3150 (4)	0.1097 (3)	0.0539 (9)
H4A	0.1974	0.3158	0.1199	0.065*
H4B	0.0080	0.3287	0.0399	0.065*
C5	0.0073 (5)	0.4269 (3)	0.1896 (3)	0.0492 (8)
H5A	−0.1279	0.4427	0.1669	0.059*
H5B	0.0921	0.5061	0.1915	0.059*
C6	0.0320 (4)	0.4019 (3)	0.3006 (2)	0.0381 (7)
H6	−0.0204	0.4722	0.3446	0.046*
C7	0.2472 (4)	0.3925 (3)	0.3542 (2)	0.0328 (6)
H7	0.2449	0.3782	0.4247	0.039*
C8	−0.0841 (4)	0.2732 (3)	0.2963 (2)	0.0359 (7)
C9	0.2870 (4)	0.0391 (3)	0.2290 (2)	0.0317 (6)
C10	0.4256 (4)	0.0528 (3)	0.1678 (2)	0.0365 (7)
H10	0.4721	0.1363	0.1618	0.044*
C11	0.4958 (4)	−0.0566 (3)	0.1153 (2)	0.0405 (7)
H11	0.5920	−0.0464	0.0761	0.049*
C12	0.4230 (5)	−0.1791 (3)	0.1214 (2)	0.0410 (7)
C13	0.2850 (5)	−0.1960 (3)	0.1810 (3)	0.0509 (9)
H13	0.2359	−0.2800	0.1846	0.061*
C14	0.2202 (5)	−0.0867 (3)	0.2355 (3)	0.0458 (8)
H14	0.1295	−0.0978	0.2776	0.055*
C15	0.3781 (4)	0.5192 (3)	0.3658 (2)	0.0324 (6)
C16	0.3485 (4)	0.6307 (3)	0.4353 (2)	0.0385 (7)
H16	0.2501	0.6248	0.4739	0.046*
C17	0.4611 (4)	0.7499 (3)	0.4489 (2)	0.0427 (7)
H17	0.4379	0.8238	0.4951	0.051*
C18	0.6087 (4)	0.7574 (3)	0.3925 (2)	0.0402 (7)
C19	0.6428 (4)	0.6494 (3)	0.3236 (3)	0.0438 (8)
H19	0.7429	0.6555	0.2862	0.053*
C20	0.5260 (4)	0.5304 (3)	0.3101 (2)	0.0395 (7)
H20	0.5480	0.4572	0.2628	0.047*
N1	0.3217 (3)	0.2793 (2)	0.2964 (2)	0.0328 (5)
O1	−0.2151 (3)	0.2611 (2)	0.34451 (19)	0.0541 (6)
H1A	0.434 (5)	0.275 (3)	0.322 (2)	0.039 (9)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.1029 (3)	0.0451 (3)	0.0682 (3)	0.0312 (2)	0.0296 (2)	−0.0015 (2)
Br2	0.0736 (3)	0.0415 (2)	0.0772 (3)	−0.01884 (18)	0.0181 (2)	0.0021 (2)
C1	0.0309 (13)	0.0280 (16)	0.0342 (15)	0.0023 (11)	0.0088 (11)	0.0031 (13)
C2	0.0268 (13)	0.0318 (17)	0.0449 (17)	−0.0002 (11)	0.0073 (12)	0.0034 (14)
C3	0.0399 (17)	0.053 (2)	0.0409 (17)	0.0099 (15)	0.0012 (14)	−0.0005 (16)
C4	0.0465 (18)	0.075 (3)	0.0428 (18)	0.0069 (17)	0.0072 (15)	0.0215 (19)
C5	0.0419 (17)	0.042 (2)	0.061 (2)	0.0033 (14)	−0.0021 (15)	0.0169 (18)
C6	0.0304 (14)	0.0334 (18)	0.0474 (17)	0.0084 (12)	0.0075 (13)	−0.0002 (14)
C7	0.0303 (14)	0.0303 (17)	0.0354 (15)	0.0046 (11)	0.0072 (12)	0.0004 (13)
C8	0.0250 (13)	0.0402 (19)	0.0393 (16)	0.0052 (12)	0.0051 (12)	0.0018 (14)
C9	0.0292 (13)	0.0279 (17)	0.0355 (15)	0.0033 (11)	0.0039 (11)	0.0035 (13)
C10	0.0367 (15)	0.0267 (17)	0.0438 (17)	−0.0008 (12)	0.0095 (13)	0.0032 (14)
C11	0.0420 (16)	0.039 (2)	0.0412 (17)	0.0065 (14)	0.0151 (13)	0.0026 (15)
C12	0.0487 (17)	0.0314 (19)	0.0393 (16)	0.0148 (14)	0.0050 (14)	−0.0009 (14)
C13	0.061 (2)	0.0243 (19)	0.069 (2)	0.0026 (15)	0.0199 (18)	0.0094 (17)
C14	0.0490 (18)	0.035 (2)	0.060 (2)	0.0049 (14)	0.0265 (16)	0.0117 (16)
C15	0.0301 (14)	0.0289 (17)	0.0346 (15)	0.0053 (11)	0.0031 (12)	0.0013 (13)
C16	0.0368 (15)	0.0357 (19)	0.0388 (16)	0.0010 (13)	0.0090 (13)	−0.0019 (14)
C17	0.0474 (17)	0.0328 (19)	0.0413 (17)	0.0047 (14)	0.0062 (14)	−0.0048 (14)
C18	0.0405 (16)	0.0307 (18)	0.0441 (17)	−0.0013 (13)	−0.0001 (13)	0.0062 (15)
C19	0.0384 (16)	0.041 (2)	0.0535 (19)	0.0016 (14)	0.0173 (14)	0.0080 (16)
C20	0.0381 (15)	0.0325 (18)	0.0466 (17)	0.0059 (13)	0.0133 (13)	0.0005 (14)
N1	0.0245 (12)	0.0277 (15)	0.0420 (14)	0.0035 (10)	0.0055 (10)	−0.0013 (11)
O1	0.0373 (12)	0.0599 (16)	0.0651 (15)	0.0028 (10)	0.0245 (11)	0.0019 (13)

Geometric parameters (Å, º) top

Br1—C12	1.899 (3)	C7—H7	0.9800
Br2—C18	1.896 (3)	C8—O1	1.216 (3)
C1—N1	1.461 (4)	C9—C10	1.384 (4)
C1—C9	1.510 (4)	C9—C14	1.384 (4)
C1—C2	1.560 (4)	C10—C11	1.386 (4)
C1—H1	0.9800	C10—H10	0.9300
C2—C8	1.497 (4)	C11—C12	1.362 (4)
C2—C3	1.532 (4)	C11—H11	0.9300
C2—H2	0.9800	C12—C13	1.372 (5)
C3—C4	1.519 (5)	C13—C14	1.377 (5)
C3—H3A	0.9700	C13—H13	0.9300
C3—H3B	0.9700	C14—H14	0.9300
C4—C5	1.516 (5)	C15—C20	1.381 (4)
C4—H4A	0.9700	C15—C16	1.388 (4)
C4—H4B	0.9700	C16—C17	1.379 (4)
C5—C6	1.531 (5)	C16—H16	0.9300
C5—H5A	0.9700	C17—C18	1.380 (4)
C5—H5B	0.9700	C17—H17	0.9300
C6—C8	1.498 (4)	C18—C19	1.369 (4)
C6—C7	1.554 (4)	C19—C20	1.392 (4)
C6—H6	0.9800	C19—H19	0.9300
C7—N1	1.461 (4)	C20—H20	0.9300
C7—C15	1.511 (4)	N1—H1A	0.80 (3)

N1—C1—C9	112.3 (2)	O1—C8—C2	123.9 (3)
N1—C1—C2	109.5 (2)	O1—C8—C6	124.0 (3)
C9—C1—C2	110.5 (2)	C2—C8—C6	112.0 (2)
N1—C1—H1	108.1	C10—C9—C14	118.0 (3)
C9—C1—H1	108.1	C10—C9—C1	123.1 (3)
C2—C1—H1	108.1	C14—C9—C1	118.8 (3)
C8—C2—C3	109.2 (3)	C9—C10—C11	120.7 (3)
C8—C2—C1	105.7 (2)	C9—C10—H10	119.7
C3—C2—C1	115.4 (2)	C11—C10—H10	119.7
C8—C2—H2	108.8	C12—C11—C10	119.6 (3)
C3—C2—H2	108.8	C12—C11—H11	120.2
C1—C2—H2	108.8	C10—C11—H11	120.2
C4—C3—C2	114.2 (3)	C11—C12—C13	121.0 (3)
C4—C3—H3A	108.7	C11—C12—Br1	119.4 (2)
C2—C3—H3A	108.7	C13—C12—Br1	119.6 (2)
C4—C3—H3B	108.7	C12—C13—C14	119.0 (3)
C2—C3—H3B	108.7	C12—C13—H13	120.5
H3A—C3—H3B	107.6	C14—C13—H13	120.5
C5—C4—C3	112.7 (3)	C13—C14—C9	121.5 (3)
C5—C4—H4A	109.1	C13—C14—H14	119.2
C3—C4—H4A	109.1	C9—C14—H14	119.2
C5—C4—H4B	109.1	C20—C15—C16	117.9 (3)
C3—C4—H4B	109.1	C20—C15—C7	123.3 (3)
H4A—C4—H4B	107.8	C16—C15—C7	118.8 (2)
C4—C5—C6	114.0 (3)	C17—C16—C15	121.8 (3)
C4—C5—H5A	108.7	C17—C16—H16	119.1
C6—C5—H5A	108.7	C15—C16—H16	119.1
C4—C5—H5B	108.7	C16—C17—C18	118.8 (3)
C6—C5—H5B	108.7	C16—C17—H17	120.6
H5A—C5—H5B	107.6	C18—C17—H17	120.6
C8—C6—C5	108.9 (3)	C19—C18—C17	121.1 (3)
C8—C6—C7	106.3 (2)	C19—C18—Br2	119.8 (2)
C5—C6—C7	115.2 (2)	C17—C18—Br2	119.1 (2)
C8—C6—H6	108.8	C18—C19—C20	119.3 (3)
C5—C6—H6	108.8	C18—C19—H19	120.4
C7—C6—H6	108.8	C20—C19—H19	120.4
N1—C7—C15	112.1 (2)	C15—C20—C19	121.1 (3)
N1—C7—C6	110.0 (2)	C15—C20—H20	119.4
C15—C7—C6	111.1 (2)	C19—C20—H20	119.4
N1—C7—H7	107.8	C1—N1—C7	113.8 (2)
C15—C7—H7	107.8	C1—N1—H1A	110 (2)
C6—C7—H7	107.8	C7—N1—H1A	111 (2)

N1—C1—C2—C8	−58.5 (3)	C1—C9—C10—C11	−178.8 (3)
C9—C1—C2—C8	177.2 (2)	C9—C10—C11—C12	2.1 (5)
N1—C1—C2—C3	62.2 (3)	C10—C11—C12—C13	−1.8 (5)
C9—C1—C2—C3	−62.1 (3)	C10—C11—C12—Br1	177.4 (2)
C8—C2—C3—C4	51.9 (3)	C11—C12—C13—C14	−0.1 (5)
C1—C2—C3—C4	−66.9 (4)	Br1—C12—C13—C14	−179.4 (3)
C2—C3—C4—C5	−45.1 (4)	C12—C13—C14—C9	1.8 (5)
C3—C4—C5—C6	45.8 (4)	C10—C9—C14—C13	−1.5 (5)
C4—C5—C6—C8	−53.2 (3)	C1—C9—C14—C13	176.9 (3)
C4—C5—C6—C7	66.0 (4)	N1—C7—C15—C20	12.5 (4)
C8—C6—C7—N1	56.8 (3)	C6—C7—C15—C20	−111.0 (3)
C5—C6—C7—N1	−63.8 (3)	N1—C7—C15—C16	−167.8 (3)
C8—C6—C7—C15	−178.4 (2)	C6—C7—C15—C16	68.6 (3)
C5—C6—C7—C15	61.0 (3)	C20—C15—C16—C17	0.4 (4)
C3—C2—C8—O1	122.1 (3)	C7—C15—C16—C17	−179.2 (3)
C1—C2—C8—O1	−113.2 (3)	C15—C16—C17—C18	−0.9 (5)
C3—C2—C8—C6	−60.8 (3)	C16—C17—C18—C19	0.6 (5)
C1—C2—C8—C6	63.9 (3)	C16—C17—C18—Br2	179.6 (2)
C5—C6—C8—O1	−121.4 (3)	C17—C18—C19—C20	0.1 (5)
C7—C6—C8—O1	113.9 (3)	Br2—C18—C19—C20	−178.9 (2)
C5—C6—C8—C2	61.4 (3)	C16—C15—C20—C19	0.4 (4)
C7—C6—C8—C2	−63.2 (3)	C7—C15—C20—C19	180.0 (3)
N1—C1—C9—C10	−17.2 (4)	C18—C19—C20—C15	−0.6 (5)
C2—C1—C9—C10	105.4 (3)	C9—C1—N1—C7	−178.3 (2)
N1—C1—C9—C14	164.3 (3)	C2—C1—N1—C7	58.5 (3)
C2—C1—C9—C14	−73.0 (3)	C15—C7—N1—C1	178.2 (2)
C14—C9—C10—C11	−0.4 (4)	C6—C7—N1—C1	−57.6 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1ⁱ	0.80 (3)	2.42 (3)	3.191 (3)	162 (3)
C16—H16···O1ⁱⁱ	0.93	2.53	3.242 (3)	133

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

Experimental details

Crystal data
Chemical formula	C₂₀H₁₉Br₂NO
M_r	449.18
Crystal system, space group	Triclinic, P1
Temperature (K)	298
a, b, c (Å)	6.9415 (3), 10.4489 (4), 13.2888 (5)
α, β, γ (°)	101.542 (2), 100.391 (2), 94.472 (2)
V (Å³)	922.34 (6)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	4.40
Crystal size (mm)	0.38 × 0.25 × 0.20

Data collection
Diffractometer	Bruker SMART CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker 1999)
T_min, T_max	0.280, 0.415
No. of measured, independent and observed [I > 2σ(I)] reflections	12376, 4036, 2805
R_int	0.024
(sin θ/λ)_max (Å⁻¹)	0.668

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.038, 0.089, 1.02
No. of reflections	4036
No. of parameters	221
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.85, −0.92

Computer programs: SMART (Bruker–Nonius, 2004), SAINT-Plus (Bruker–Nonius, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1ⁱ	0.80 (3)	2.42 (3)	3.191 (3)	162 (3)
C16—H16···O1ⁱⁱ	0.93	2.53	3.242 (3)	133

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

Acknowledgements

The authors acknowledge the Department of Chemistry, IIT Madras, for the X-ray data collection.

References

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