Crystal structure of 1-[3,5-bis­(tri­fluoro­meth­yl)phen­yl]-2-bromo­ethan-1-one

The title compound crystallizes with four mol­ecules in the unit cell (Z = 4) and one formula unit in the asymmetric unit. In the crystal, mol­ecules are linked in a head-to-tail fashion into dimers along the b-axis direction through weak C—H⋯Br and C—O⋯Csp ² inter­actions. C—H⋯O, C—F⋯π and F⋯F inter­actions are also observed

Abstract

The title compound, C₁₀H₅BrF₆O, synthesized via continuous stirring of 3,5-bis­(tri­fluoro­meth­yl) aceto­phenone with bromine in an acidic medium and concentrated under reduced pressure, crystallizes with four mol­ecules in the unit cell (Z = 4) and one formula unit in the asymmetric unit. In the crystal, mol­ecules are linked in a head-to-tail fashion into dimers along the b-axis direction through weak C—H⋯Br and C—O⋯Csp ² inter­actions. C—H⋯O, C—F⋯π and F⋯F inter­actions are also observed.

Chemical context  

Substituted phenacyl bromides can be achieved by α-bromination of substituted ketones employing suitable bromination reagents such as mol­ecular bromine (Curran & Chang, 1989 ▸), copper bromide (King & Ostrum, 1964 ▸), N-bromo­succinimide (Tanemura et al., 2004 ▸), 3-methyl­imidazolium tribromide (Chiappe et al., 2004 ▸) and hydrogen bromide (Podgoršek et al., 2009 ▸). In our previous communications, we tried to develop inter­mediates (Chopra et al., 2007 ▸) for the construction of biologically active heterocyclic compounds (Kasumbwe et al., 2017 ▸). In this context, the title compound serves as a synthetic precursor and finds application in the construction of pharmacologically active heterocyclic compounds (Venugopala et al., 2018 ▸, 2007 ▸).

Structural commentary  

A displacement ellipsoid plot of the title compound with the atom labelling is shown in Fig. 1 ▸. The compound crystallizes in the monoclinic space group P2₁/c with one mol­ecule in the asymmetric unit and four mol­ecules in the unit cell (Z = 4). The torsion angle between the alkyl bromide unit and the phenyl ring (C3—C2—C1—Br1) is −179.6 (3)° whereas that between the alkyl bromide and carbonyl parts (O1—C2—C1—Br1) is 0.3 (5)°, which shows a preference for a syn orientation of the alkyl bromide unit with respect to the carbonyl group.

Figure 1.

The asymmetric unit of the title compound, with 50% probability ellipsoids.

Supra­molecular features  

In the crystal, the mol­ecules are arranged in a head-to-tail fashion, forming dimers sustained by C—Br⋯H and >C=O⋯π(>C=O) (O⋯π = 3.252 Å) inter­actions. The dimers are linked along the c-axis direction by C—H⋯O and C—F⋯π inter­actions (Table 1 ▸, Fig. 2 ▸). The assembly of dimers is further extended along the a-axis direction by F1⋯F4(x,  − y,  + z) [2.868 (4) Å] inter­actions, resulting in a bilayer which further packs in parallel fashion along the a-axis direction (Fig. 3 ▸).

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1A⋯O1i	0.99	2.57	3.501 (5)	157
C1—Br1⋯H4ii	1.92 (1)	2.94 (11)	3.882	169
C2—O1⋯C2iii	1.20 (1)	3.05 (1)	4.126	149 (1)
C9—F2⋯πiv	1.32 (1)	3.89	4.848	130

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .

Figure 2.

Dimer assembled through C—H⋯Br and >C=O⋯π(>C=O) inter­actions (left) and dimers extending along the b-axis direction via C—H⋯O and C—F⋯π inter­actions (Table 1 ▸).

Figure 3.

F⋯F inter­actions resulting in a bilayer that packs in a parallel fashion along the a-axis direction.

Database survey  

There are more than 1000 crystal structure of phenyl ethanone derivatives in the Cambridge Structural Database (CSD) (Conquest Version 1.17; Groom et al., 2016 ▸) but none of them gave a hit for 1-[3,5-bis­(tri­fluoro­meth­yl)phen­yl]-2-bromo­ethanone. However, the crystal structures of related derivatives have been reported. These include phenyl 2-bromo­ethanone (URELEJ; Betz et al., 2011 ▸) and a phenyl 2-bromo­ethanone complex (VIVFIP; Laube et al., 1991 ▸). The first compound, Z = 4, features two prominent hydrogen bonds involving the oxygen atom while in the second, also Z = 4, the oxygen atom forms a complex with anti­mony penta­chloride.

Synthesis and crystallization  

A stirred solution of 3,5-bis­(tri­fluoro­meth­yl) aceto­phenone (0.5 g, 1.95 mmol) in acetic acid (5 mL) was added dropwise to bromine (0.312 g, 1.95 mmol) in acetic acid. The reaction medium was stirred at room temperature for 5 h. To the resulting mixture, water (5 mL) was added and the mixture was concentrated under reduced pressure. The residue obtained was diluted with ethyl­acetate (10 mL), the organic layer washed with water (10 mL) and a sodium bicarbonate solution (5 mL), and filtered through dried sodium sulfate and evaporated to obtain 1-(3,5-bis­(tri­fluoro­meth­yl)phen­yl)-2-bromo­ethanone as a light-yellow solid in 62% yield. m.p: 317–318 K. ¹H NMR: (CDCl₃, 600 MHz): 8.44 (2H, s), 8.13 (1H, s), 4.48 (2H, s); ¹³C NMR: (CDCl₃, 150 MHz): 188.81, 135.31, 133.06, 132.83, 132.60, 128.99, 127.08, 127.06, 125.42, 123.61, 121.80, 120.00, 29.46.

Refinement  

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. Hydrogen atoms were placed in idealized positions (C—H = 0.95–0.99 Å) and refined using a riding model with U _iso(H) = 1.2–1.5U _eq(C).

Table 2. Experimental details.

Crystal data
Chemical formula	C10H5BrF6O
M r	335.04
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	153
a, b, c (Å)	14.156 (5), 5.0111 (16), 15.535 (5)
β (°)	104.316 (5)
V (Å3)	1067.7 (6)
Z	4
Radiation type	Mo Kα
μ (mm−1)	3.92
Crystal size (mm)	0.23 × 0.09 × 0.06
Data collection
Diffractometer	Bruker Kappa APEXII DUO
Absorption correction	Multi-scan (SADABS; Bruker, 2012 ▸)
T min, T max	0.442, 0.759
No. of measured, independent and observed [I > 2σ(I)] reflections	11628, 2405, 1741
R int	0.060
(sin θ/λ)max (Å−1)	0.646
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.041, 0.103, 1.03
No. of reflections	2405
No. of parameters	163
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.78, −1.12

Computer programs: APEX2 and SAINT (Bruker, 2012 ▸), SHELXS (Sheldrick, 2008 ▸), SHELXL2014 (Sheldrick, 2015 ▸), Mercury (Macrae et al., 2008 ▸), PLATON (Spek, 2009 ▸) and PARST (Nardelli, 1995 ▸).

Supplementary Material

CCDC reference: 1843826

Additional supporting information: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Crystal data

C10H5BrF6O	F(000) = 648
Mr = 335.04	Dx = 2.084 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2405 reflections
a = 14.156 (5) Å	θ = 2.7–27.4°
b = 5.0111 (16) Å	µ = 3.92 mm−1
c = 15.535 (5) Å	T = 153 K
β = 104.316 (5)°	Needle, colorless
V = 1067.7 (6) Å3	0.23 × 0.09 × 0.06 mm
Z = 4

Data collection

Bruker Kappa APEXII DUO diffractometer	2405 independent reflections
Radiation source: fine-focus sealed tube	1741 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.060
ω scans	θmax = 27.4°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2012)	h = −18→18
Tmin = 0.442, Tmax = 0.759	k = −6→6
11628 measured reflections	l = −20→20

Refinement

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)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.103	H-atom parameters constrained
S = 1.03	w = 1/[σ2(Fo2) + (0.0541P)2 + 0.3605P] where P = (Fo2 + 2Fc2)/3
2405 reflections	(Δ/σ)max < 0.001
163 parameters	Δρmax = 0.78 e Å−3
0 restraints	Δρmin = −1.12 e Å−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.60416 (2)	0.14882 (9)	0.09433 (3)	0.03259 (16)
F1	0.21893 (17)	0.1990 (6)	0.38145 (15)	0.0468 (7)
F2	0.1420 (2)	−0.0983 (6)	0.29661 (17)	0.0597 (8)
F3	0.07527 (19)	0.2781 (7)	0.3050 (2)	0.0655 (9)
F4	0.19332 (17)	0.8957 (5)	0.00403 (18)	0.0480 (7)
F5	0.07651 (19)	0.8912 (5)	0.06942 (16)	0.0484 (7)
F6	0.07736 (15)	0.6137 (5)	−0.03417 (14)	0.0362 (6)
O1	0.45527 (18)	−0.0571 (6)	0.18612 (18)	0.0329 (6)
C1	0.4825 (2)	0.3126 (8)	0.0979 (3)	0.0278 (9)
H1A	0.4955	0.4921	0.1249	0.033*
H1B	0.4423	0.3352	0.0365	0.033*
C2	0.4258 (3)	0.1506 (8)	0.1506 (2)	0.0258 (8)
C3	0.3301 (2)	0.2646 (8)	0.1557 (2)	0.0237 (8)
C4	0.2889 (3)	0.1673 (8)	0.2217 (2)	0.0264 (8)
H4	0.3218	0.0353	0.2620	0.032*
C5	0.1991 (2)	0.2642 (8)	0.2285 (2)	0.0255 (8)
C6	0.1483 (2)	0.4474 (8)	0.1686 (2)	0.0259 (8)
H6	0.0857	0.5070	0.1722	0.031*
C7	0.1901 (2)	0.5434 (8)	0.1028 (2)	0.0239 (8)
C8	0.2806 (3)	0.4557 (8)	0.0968 (2)	0.0255 (8)
H8	0.3091	0.5261	0.0524	0.031*
C9	0.1583 (3)	0.1609 (9)	0.3022 (3)	0.0313 (9)
C10	0.1348 (3)	0.7374 (9)	0.0362 (3)	0.0308 (9)

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Br1	0.0200 (2)	0.0386 (3)	0.0398 (3)	0.00282 (17)	0.00868 (15)	−0.0043 (2)
F1	0.0405 (14)	0.072 (2)	0.0306 (13)	−0.0144 (13)	0.0130 (11)	−0.0053 (12)
F2	0.093 (2)	0.044 (2)	0.0531 (17)	−0.0302 (15)	0.0394 (16)	−0.0108 (13)
F3	0.0370 (14)	0.094 (2)	0.077 (2)	0.0245 (15)	0.0356 (14)	0.0359 (17)
F4	0.0332 (13)	0.0366 (17)	0.0686 (18)	−0.0044 (11)	0.0020 (12)	0.0237 (13)
F5	0.0500 (14)	0.0464 (18)	0.0440 (14)	0.0282 (13)	0.0024 (11)	−0.0025 (12)
F6	0.0292 (11)	0.0432 (17)	0.0324 (12)	−0.0001 (10)	0.0005 (9)	−0.0029 (10)
O1	0.0285 (14)	0.0294 (18)	0.0420 (16)	0.0055 (12)	0.0109 (12)	0.0065 (13)
C1	0.0188 (16)	0.029 (3)	0.036 (2)	0.0010 (15)	0.0074 (15)	−0.0008 (17)
C2	0.0235 (17)	0.023 (2)	0.030 (2)	−0.0036 (16)	0.0046 (14)	−0.0040 (17)
C3	0.0203 (17)	0.023 (2)	0.028 (2)	−0.0016 (15)	0.0056 (15)	−0.0021 (16)
C4	0.0237 (17)	0.022 (2)	0.032 (2)	−0.0005 (15)	0.0052 (15)	−0.0020 (16)
C5	0.0230 (18)	0.025 (2)	0.028 (2)	−0.0036 (15)	0.0061 (15)	−0.0023 (16)
C6	0.0189 (16)	0.025 (2)	0.034 (2)	0.0007 (15)	0.0056 (15)	−0.0002 (17)
C7	0.0190 (16)	0.021 (2)	0.029 (2)	0.0009 (14)	0.0017 (14)	−0.0010 (16)
C8	0.0274 (18)	0.021 (2)	0.028 (2)	−0.0007 (15)	0.0071 (15)	−0.0012 (16)
C9	0.0253 (18)	0.032 (3)	0.037 (2)	−0.0022 (17)	0.0085 (16)	−0.0016 (18)
C10	0.0263 (19)	0.029 (2)	0.034 (2)	0.0032 (17)	0.0013 (16)	−0.0008 (18)

Geometric parameters (Å, º)

Br1—C1	1.921 (4)	C3—C4	1.388 (5)
F1—C9	1.329 (4)	C3—C8	1.389 (5)
F2—C9	1.319 (5)	C4—C5	1.388 (5)
F3—C9	1.325 (4)	C4—H4	0.9500
F4—C10	1.330 (5)	C5—C6	1.377 (5)
F5—C10	1.324 (5)	C5—C9	1.497 (5)
F6—C10	1.343 (4)	C6—C7	1.388 (5)
O1—C2	1.203 (5)	C6—H6	0.9500
C1—C2	1.516 (5)	C7—C8	1.378 (5)
C1—H1A	0.9900	C7—C10	1.492 (5)
C1—H1B	0.9900	C8—H8	0.9500
C2—C3	1.490 (5)
C2—C1—Br1	112.7 (3)	C7—C6—H6	120.6
C2—C1—H1A	109.1	C8—C7—C6	120.8 (3)
Br1—C1—H1A	109.1	C8—C7—C10	119.9 (3)
C2—C1—H1B	109.1	C6—C7—C10	119.3 (3)
Br1—C1—H1B	109.1	C7—C8—C3	120.1 (3)
H1A—C1—H1B	107.8	C7—C8—H8	119.9
O1—C2—C3	121.6 (3)	C3—C8—H8	119.9
O1—C2—C1	122.7 (3)	F2—C9—F3	107.2 (3)
C3—C2—C1	115.7 (3)	F2—C9—F1	105.4 (3)
C4—C3—C8	119.5 (3)	F3—C9—F1	106.3 (3)
C4—C3—C2	117.3 (3)	F2—C9—C5	112.7 (3)
C8—C3—C2	123.1 (3)	F3—C9—C5	112.7 (3)
C5—C4—C3	119.5 (4)	F1—C9—C5	112.1 (3)
C5—C4—H4	120.2	F5—C10—F4	107.8 (4)
C3—C4—H4	120.2	F5—C10—F6	106.0 (3)
C6—C5—C4	121.2 (3)	F4—C10—F6	106.1 (3)
C6—C5—C9	120.8 (3)	F5—C10—C7	112.4 (3)
C4—C5—C9	118.0 (4)	F4—C10—C7	112.4 (3)
C5—C6—C7	118.8 (3)	F6—C10—C7	111.8 (3)
C5—C6—H6	120.6
Br1—C1—C2—O1	0.3 (5)	C10—C7—C8—C3	−176.6 (4)
Br1—C1—C2—C3	−179.6 (3)	C4—C3—C8—C7	−1.4 (6)
O1—C2—C3—C4	17.6 (5)	C2—C3—C8—C7	176.9 (3)
C1—C2—C3—C4	−162.5 (3)	C6—C5—C9—F2	117.1 (4)
O1—C2—C3—C8	−160.8 (4)	C4—C5—C9—F2	−62.1 (5)
C1—C2—C3—C8	19.1 (5)	C6—C5—C9—F3	−4.4 (6)
C8—C3—C4—C5	−0.6 (6)	C4—C5—C9—F3	176.5 (4)
C2—C3—C4—C5	−179.0 (3)	C6—C5—C9—F1	−124.2 (4)
C3—C4—C5—C6	2.7 (6)	C4—C5—C9—F1	56.6 (5)
C3—C4—C5—C9	−178.1 (3)	C8—C7—C10—F5	−151.0 (4)
C4—C5—C6—C7	−2.7 (6)	C6—C7—C10—F5	30.9 (5)
C9—C5—C6—C7	178.2 (3)	C8—C7—C10—F4	−29.3 (5)
C5—C6—C7—C8	0.5 (6)	C6—C7—C10—F4	152.6 (4)
C5—C6—C7—C10	178.7 (4)	C8—C7—C10—F6	89.9 (4)
C6—C7—C8—C3	1.5 (6)	C6—C7—C10—F6	−88.2 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1A···O1i	0.99	2.57	3.501 (5)	157
C1—Br1···H4ii	1.92 (1)	2.94 (11)	3.882	169
C2—O1···C2iii	1.20 (1)	3.05 (1)	4.126	149 (1)
C9—F2···πiv	1.32 (1)	3.89	4.848	130

Symmetry codes: (i) x, y+1, z; (ii) −x+1, y+1/2, −z+1/2; (iii) −x+1, y−1/2, −z+1/2; (iv) x, y−1, z.

Funding Statement

This work was funded by National Research Foundation grants 96807 and 98884. Durban University of Technology grant . VNIT Nagpur grant to Keshab M. Bairagi.