Crystal structure of 1-(4-bromo­phen­yl)but-3-yn-1-one

Siddiqui, S.K.; Ramana, C.V.; Gonnade, R.G.

doi:10.1107/S205698902300508X

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ISSN: 2056-9890

Volume 79| Part 7| July 2023| Pages 633-636

https://doi.org/10.1107/S205698902300508X

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Crystal structure of 1-(4-bromophenyl)but-3-yn-1-one

Shaziyaparveen K. Siddiqui,^a,^b C. V. Ramana ^a,^b and Rajesh G. Gonnade ^c,^b ^*

^aDivision of Organic Synthesis, CSIR-National Chemical Laboratory, Dr. Homi, Bhabha Road, Pashan, Pune-411008, India, ^bAcademy of Scientific and Innovative Research (AcSIR), Sector 19, Kamla Nehru Nagar, Ghaziabad, Uttar Pradesh 201002, India, and ^cPhysical & Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India
^*Correspondence e-mail: rg.gonnade@ncl.res.in

Edited by D. Chopra, Indian Institute of Science Education and Research Bhopal, India (Received 12 May 2023; accepted 7 June 2023; online 13 June 2023)

The title compound, 1-(4-bromophenyl)but-3-yn-1-one, C₁₀H₇BrO, crystallizes in the monoclinic space group P2₁/n with one molecule in the asymmetric unit. The structure displays a planar geometry. The crystal structure is consolidated by C—H⋯O hydrogen bonding and a short C=O⋯C≡C (acetylene) contacts. Hirshfeld surface analysis indicates that H⋯H, C⋯H/H⋯C and H⋯Br/Br⋯H interactions play a more important role in consolidating the crystal structure compared to H⋯O/O⋯H and C⋯C contacts.

Keywords: crystal structure; intermolecular interactions; Hirshfeld surface analysis.

CCDC reference: 2268276

1. Chemical context

The title compound 1-(4-bromophenyl)but-3-yn-1-one (1) was obtained as a side product during the synthesis of 5-(4-bromophenyl)isoxazole-3-carboxylic acid (2) from the NaOH-mediated hydrolysis of ethyl 5-(4-bromophenyl)isoxazole-3-carboxylate (3). These arylisoxazole carboxylic acids have been identified as potential isosteres of aryl diketo acid in the design of novel HIV-1 integrase inhibitors (Zeng et al., 2008 ). The presence of three distinct functional groups, viz. alkyne, bromo, and carbonyl, offers an intriguing opportunity to explore how intermolecular interactions contribute to the cohesion of the crystal structure.

2. Structural commentary

The title compound crystallizes in the monoclinic P2₁/n centrosymmetric space group with one molecule of 1 in the asymmetric unit (Fig. 1). The structure displays a planar geometry [torsion angle C5—C1—C8—C9 = 175.4 (3)^o, only the C5 atom of phenyl ring is considered and not the full fragment]. The phenyl ring makes a dihedral angle of 5.4 (2)° with the least-squares plane through the O1/C1/C8–C10 fragment.

Figure 1
The asymmetric unit of 1 with the atom labelling. Displacement ellipsoids represent 30% probability levels.

3. Supramolecular features

In the crystal, the closely associated molecules of 1 generate two different helical assemblies across the crystallographic 2₁-screw axis (b-axis). The helical assembly generated using C1=O1⋯C9ⁱ≡C10ⁱ (acetylene, C=O⋯π) contacts [symmetry code: (i) −x + $[{1\over 2}]$ , y + $[{1\over 2}]$ , −z + $[{3\over 2}]$ ] (Li et al., 2019 ; Mooibroek, et al., 2008 ) has a sheet structure (Fig. 2, Table 1), while the helical assembly created using C—H⋯O (C8—H8A⋯O1ⁱⁱ) contacts [symmetry code: (ii) −x + $[{3\over 2}]$ , y − $[{1\over 2}]$ , −z + $[{3\over 2}]$ ] (Desiraju & Steiner, 2001 ) has a proper helical structure (Fig. 3, Table 1). The helical assembly created using the short C1=O1⋯C9≡C10 contacts is further supported by marginal C—H⋯π [symmetry code: (iii) −x + $[{1\over 2}]$ , y − $[{1\over 2}]$ , −z + $[{3\over 2}]$ ] contacts involving the phenyl ring (C7—H7) and the π cloud of the acetylene moiety. Both helices are intertwined and form a two-dimensional sheet structure roughly along the a-axis direction. Along the longer c-axis, molecules are loosely connected using weak C—H⋯Br (C10—H10⋯Br1^iv contacts [symmetry code: (iv) x − $[{3\over 2}]$ , −y + $[{1\over 2}]$ , z − $[{1\over 2}]$ ] (van den Berg & Seddon, 2003 ), generating the extended assembly (Figs. 2 and 3, Table 1).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—O1⋯C9ⁱ		3.13 (1)		154 (1)
C8—H8A⋯O1ⁱⁱ	1.02 (4)	2.31 (4)	3.259 (5)	156 (3)
C7—H7⋯C10ⁱⁱⁱ	1.06 (3)	2.71 (4)	3.626 (5)	144 (3)
C10—H10⋯Br1^iv	0.93	2.68	3.305 (5)	126
Symmetry codes: (i) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (ii) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iii) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iv) $[x-{\script{3\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ .

Figure 2
A view of the molecular packing of 1 along the helical b-axis showing the association of closely linked molecules by C=O⋯C≡C (acetylene, C=O⋯π) and marginal C—H⋯π (π-cloud of acetylene molecules) contacts. Neighbouring helices along the longer c axis are linked by C—H⋯Br contacts. Symmetry codes as in Table 1

Figure 3
A view of the molecular packing of 1 along the helical b-axis showing the association of closely linked molecules by C—H⋯O contacts. Neighbouring helices along the longer c axis are linked by C—H⋯Br contacts. Symmetry codes as in Table 1

In order to visualize and quantify intermolecular interactions in 1, a Hirshfeld surface analysis (Spackman & Jayatilaka, 2009 ) was performed using Crystal Explorer 21.5 (Spackman et al., 2021 ), and the associated two-dimensional fingerprint plots (McKinnon et al., 2007 ) were generated. The Hirshfeld surfaces for the molecule in 1 are shown in Fig. 4 in which the two-dimensional fingerprint plots of the most dominant contacts are also presented. H⋯H (27.4%), H⋯C/C⋯H (22.3%) and H⋯Br/Br⋯H (22.0%) contacts are responsible for the largest contributions to the Hirshfeld surface. Besides these contacts, H⋯O/O⋯H (11.8%) and C⋯C (7.8%) interactions contribute significantly to the total Hirshfeld surface. The contributions of further contacts are only minor and amount to C⋯Br/Br⋯C (4.5%) and C⋯O/O⋯C (3.6%).

Figure 4
Three-dimensional Hirshfeld surfaces of compound 1 plotted over d_norm in the range −0.2760 to 0.9829 a.u., and Hirshfeld fingerprint plots for all contacts and those decomposed into H⋯H, H⋯C/C⋯H, H⋯Br/Br⋯H, H⋯O/O⋯H, C⋯C and C⋯Br/Br⋯C contacts. d_i and d_e denote the closest internal and external distances (in Å) from a point on the surface.

4. Database survey

A survey of the Cambridge Structural Database (version 5.43, update 4, November 2022; Groom et al., 2016 ) revealed that no crystal structure of compound 1 has been reported. Moreover, no crystal structure similar to that of compound 1 has been reported. However, focusing only on the 1-phenylbut-3-yn-1-one unit yielded 24 hits with not much similarity with the title compound. The most similar structure with respect to compound 1 is 3-phenyl-2-(phenylethynyl)-1H-inden-1-one (FEGDOO; Kumar et al., 2022 ).

5. Synthesis and crystallization

A solution of methyl ester 3 (100 mg, 0.35 mmol) and 1N NaOH (3 mL) and methanol (3 mL) was heated to reflux for 3 h. After completion of the reaction as indicated by TLC, the reaction mixture was cooled to room temperature and neutralized with a solution of 3N HCl and then extracted with dichloromethane (3 × 10 mL). The combined organic layer was washed with brine and concentrated. The resulting crude was purified by column chromatography (30% ethyl acetate in petroleum ether) to afford the acid 2 (70 mg, 74% yield) and an alkyne, the title compound 1 (8 mg, 11% yield) as colourless solids. Colourless crystals of the title compound 1 suitable for single crystal X-ray diffraction analysis were obtained by slow evaporation of an ethanol solution.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. All H atoms (except the acetylene H atom) were located in difference-Fourier map and refined isotropically. The acetylene (—C≡C—H) H atom was placed in a geometrically idealized position using HFIX 163. It was constrained to ride on its parent atom, with U_iso(H) = 1.2U_eq(C) for acetylene. The long C8—H8A distance [1.02 (4) Å] could be the result of its involvement in the directional C— H⋯O hydrogen-bond formation with O1.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₀H₇BrO
M_r	223.07
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	297
a, b, c (Å)	4.471 (2), 9.032 (4), 21.652 (11)
β (°)	92.252 (8)
V (Å³)	873.7 (7)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	4.65
Crystal size (mm)	0.35 × 0.28 × 0.13

Data collection
Diffractometer	Bruker SMART APEX
Absorption correction	Multi-scan (SADABS; Bruker 2016 )
T_min, T_max	0.293, 0.583
No. of measured, independent and observed [I > 2σ(I)] reflections	4994, 1965, 1397
R_int	0.043
(sin θ/λ)_max (Å⁻¹)	0.664

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.048, 0.140, 1.02
No. of reflections	1965
No. of parameters	133
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.40, −0.62
Computer programs: APEX3 and SAINT-Plus (Bruker, 2016), SHELXS97 (Sheldrick, 2008 ), SHELXL2014/7 (Sheldrick, 2015 ), ORTEP-3 for Windows (Farrugia, 2012 ), Mercury (Macrae et al., 2020 ), SHELXTL (Sheldrick, 2008), PLATON (Spek, 2020 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 2268276

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S205698902300508X/dx2053sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S205698902300508X/dx2053Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S205698902300508X/dx2053Isup3.cml

checkCIF report

Computing details top

Data collection: APEX3 (Bruker, 2016); cell refinement: SAINT-Plus (Bruker, 2016); data reduction: SAINT-Plus (Bruker, 2016); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012), Mercury (Macrae et al., 2020); software used to prepare material for publication: SHELXTL (Sheldrick, 2008), PLATON (Spek, 2020) and publCIF (Westrip, 2010).

1-(4-Bromophenyl)but-3-yn-1-one top

Crystal data top

C₁₀H₇BrO	F(000) = 440
M_r = 223.07	D_x = 1.696 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 4.471 (2) Å	Cell parameters from 1876 reflections
b = 9.032 (4) Å	θ = 2.4–24.9°
c = 21.652 (11) Å	µ = 4.65 mm⁻¹
β = 92.252 (8)°	T = 297 K
V = 873.7 (7) Å³	Block, colourless
Z = 4	0.35 × 0.28 × 0.13 mm

Data collection top

Bruker SMART APEX diffractometer	1965 independent reflections
Radiation source: fine-focus sealed tube	1397 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.043
Phi and ω Scan scans	θ_max = 28.2°, θ_min = 2.4°
Absorption correction: multi-scan (SADABS; Bruker 2016)	h = −4→5
T_min = 0.293, T_max = 0.583	k = −11→11
4994 measured reflections	l = −27→27

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.048	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.140	w = 1/[σ²(F_o²) + (0.0812P)² + 0.1069P] where P = (F_o² + 2F_c²)/3
S = 1.02	(Δ/σ)_max = 0.002
1965 reflections	Δρ_max = 0.40 e Å⁻³
133 parameters	Δρ_min = −0.62 e Å⁻³
0 restraints

Special details top

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	0.5990 (7)	0.3666 (3)	0.79382 (16)	0.0508 (8)
Br1	1.37959 (10)	0.22006 (5)	1.02549 (2)	0.0743 (2)
C2	0.7972 (7)	0.3261 (3)	0.84766 (16)	0.0488 (7)
C3	0.9384 (9)	0.4391 (4)	0.88181 (17)	0.0581 (9)
H3	0.887 (9)	0.545 (5)	0.8679 (19)	0.080 (12)*
C4	1.1186 (9)	0.4079 (4)	0.93323 (18)	0.0615 (9)
H4	1.217 (9)	0.494 (5)	0.9555 (19)	0.077 (11)*
C5	1.1578 (9)	0.2628 (4)	0.95122 (18)	0.0556 (8)
C6	1.0233 (9)	0.1475 (4)	0.91808 (18)	0.0609 (9)
H6	1.065 (9)	0.051 (5)	0.9319 (19)	0.070 (11)*
C7	0.8439 (9)	0.1783 (4)	0.86619 (17)	0.0560 (8)
H7	0.752 (8)	0.096 (4)	0.8364 (15)	0.054 (9)*
C8	0.4544 (9)	0.2439 (4)	0.7551 (2)	0.0555 (9)
H8B	0.342 (9)	0.184 (4)	0.7824 (18)	0.056 (10)*
C9	0.2564 (10)	0.3048 (4)	0.7064 (2)	0.0666 (11)
H8A	0.617 (10)	0.187 (5)	0.734 (2)	0.068 (12)*
C10	0.1011 (10)	0.3516 (5)	0.6698 (2)	0.0783 (12)
H10	−0.0283	0.3905	0.6393	0.094*
O1	0.5514 (7)	0.4954 (2)	0.77985 (13)	0.0718 (8)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0553 (18)	0.0353 (15)	0.0622 (19)	−0.0025 (13)	0.0097 (15)	−0.0018 (14)
Br1	0.0827 (4)	0.0702 (3)	0.0688 (3)	−0.00322 (18)	−0.0116 (2)	−0.00504 (18)
C2	0.0542 (18)	0.0368 (14)	0.0563 (18)	−0.0031 (13)	0.0125 (15)	−0.0051 (14)
C3	0.076 (2)	0.0382 (16)	0.061 (2)	−0.0070 (15)	0.0057 (18)	−0.0033 (15)
C4	0.074 (2)	0.0484 (19)	0.062 (2)	−0.0152 (17)	0.0072 (18)	−0.0110 (17)
C5	0.060 (2)	0.0547 (19)	0.0524 (19)	−0.0042 (15)	0.0068 (15)	−0.0065 (16)
C6	0.077 (2)	0.0415 (18)	0.064 (2)	−0.0030 (17)	0.0016 (18)	−0.0003 (16)
C7	0.069 (2)	0.0386 (15)	0.060 (2)	−0.0030 (15)	0.0009 (17)	−0.0053 (15)
C8	0.057 (2)	0.0396 (15)	0.069 (2)	0.0016 (15)	−0.0034 (19)	−0.0029 (16)
C9	0.067 (2)	0.0464 (18)	0.087 (3)	−0.0048 (17)	0.002 (2)	−0.0019 (19)
C10	0.084 (3)	0.060 (2)	0.088 (3)	0.005 (2)	−0.032 (2)	0.017 (2)
O1	0.0875 (18)	0.0377 (12)	0.0895 (19)	0.0002 (12)	−0.0066 (16)	0.0024 (13)

Geometric parameters (Å, º) top

C1—O1	1.218 (4)	C5—C6	1.388 (5)
C1—C2	1.482 (5)	C6—C7	1.383 (5)
C1—C8	1.518 (5)	C6—H6	0.93 (4)
Br1—C5	1.895 (4)	C7—H7	1.06 (3)
C2—C3	1.397 (5)	C8—C9	1.458 (7)
C2—C7	1.407 (5)	C8—H8B	0.96 (4)
C3—C4	1.378 (6)	C8—H8A	1.02 (4)
C3—H3	1.03 (5)	C9—C10	1.117 (6)
C4—C5	1.377 (5)	C10—H10	0.9300
C4—H4	1.01 (5)

O1—C1—C2	121.6 (3)	C7—C6—C5	119.7 (3)
O1—C1—C8	119.6 (3)	C7—C6—H6	123 (3)
C2—C1—C8	118.8 (3)	C5—C6—H6	117 (3)
C3—C2—C7	118.9 (3)	C6—C7—C2	119.8 (3)
C3—C2—C1	118.7 (3)	C6—C7—H7	123.5 (18)
C7—C2—C1	122.4 (3)	C2—C7—H7	116.4 (18)
C4—C3—C2	121.1 (3)	C9—C8—C1	110.9 (3)
C4—C3—H3	123 (2)	C9—C8—H8B	110 (2)
C2—C3—H3	116 (2)	C1—C8—H8B	107 (2)
C5—C4—C3	119.2 (3)	C9—C8—H8A	107 (2)
C5—C4—H4	123 (2)	C1—C8—H8A	109 (2)
C3—C4—H4	117 (3)	H8B—C8—H8A	113 (3)
C4—C5—C6	121.3 (4)	C10—C9—C8	178.8 (6)
C4—C5—Br1	119.4 (3)	C9—C10—H10	180.0
C6—C5—Br1	119.2 (3)

O1—C1—C2—C3	−1.9 (5)	C3—C4—C5—Br1	−175.1 (3)
C8—C1—C2—C3	177.7 (3)	C4—C5—C6—C7	−0.6 (6)
O1—C1—C2—C7	177.0 (3)	Br1—C5—C6—C7	175.5 (3)
C8—C1—C2—C7	−3.4 (5)	C5—C6—C7—C2	−0.5 (6)
C7—C2—C3—C4	−0.7 (5)	C3—C2—C7—C6	1.1 (6)
C1—C2—C3—C4	178.3 (3)	C1—C2—C7—C6	−177.8 (3)
C2—C3—C4—C5	−0.4 (6)	O1—C1—C8—C9	−3.3 (6)
C3—C4—C5—C6	1.0 (6)	C2—C1—C8—C9	177.1 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—O1···C9ⁱ		3.13 (1)		154 (1)
C8—H8A···O1ⁱⁱ	1.02 (4)	2.31 (4)	3.259 (5)	156 (3)
C7—H7···C10ⁱⁱⁱ	1.06 (3)	2.71 (4)	3.626 (5)	144 (3)
C10—H10···Br1^iv	0.93	2.68	3.305 (5)	126

Symmetry codes: (i) −x+1/2, y+1/2, −z+3/2; (ii) −x+3/2, y−1/2, −z+3/2; (iii) −x+1/2, y−1/2, −z+3/2; (iv) x−3/2, −y+1/2, z−1/2.

Acknowledgements

SKS thanks the DST–INSPIRE program for a research fellowship.

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