2-Bromo­acetamide

Schwarzer, A.; Stapf, M.

doi:10.1107/S2414314624008630

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 9| Part 9| September 2024| x240863

https://doi.org/10.1107/S2414314624008630

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2-Bromoacetamide

Anke Schwarzer ^a and Manuel Stapf ^a ^*

^aInstitut für Organische Chemie, Technische Universität Bergakademie Freiberg, Leipziger Str. 29, 09599 Freiberg, Germany
^*Correspondence e-mail: Manuel.Stapf@chemie.tu-freiberg.de

Edited by S. Bernès, Benemérita Universidad Autónoma de Puebla, México (Received 1 August 2024; accepted 2 September 2024; online 30 September 2024)

The title compound, C₂H₄BrNO, crystallizes in the monoclinic space group P2₁/c with one molecule in the asymmetric unit. The almost planar molecules are organized via N—H⋯O hydrogen bonds into a ladder-type network, which can be characterized by the graph sets R²₂(8) and R²₄(8). In addition, the molecules are connected by C—H⋯O and C—H⋯Br contacts.

Keywords: crystal structure; hydrogen bonding; C—H⋯Br interaction; acetamide; carbamoyl group; carboxamide dimer.

CCDC reference: 2381424

Structure description

2-Bromoacetamide described here is isostructural to 2-chloroacetamide (Kalyanaraman et al., 1978 ; Rheingold, 2021 ), but not to 2-fluoroacetamide (Hughes & Small, 1962 ; Jeffrey et al., 1981 ).

The molecular structure of the title compound is almost planar, with the bromine atom lying only slightly out of the amide plane [distance = 0.374 (3) Å] and orientated in the opposite direction to the carbonyl oxygen atom (Fig. 1). This is reflected in the torsion angles (O1/N1)—C1—C2—Br1 with values of −166.7 (2) and 14.4 (4)°, respectively. Furthermore, an intramolecular N—H⋯Br contact of 2.69 (4) Å is observed. The crystal structure consists of layers that extend parallel to the (102) plane and are composed of centrosymmetric dimers of the title compound as the smallest supramolecular unit (Fig. 2). Within these dimers, the molecules are held together by N—H⋯O hydrogen bonds [N1—H2N⋯O1, 2.17 (5) Å; Table 1]. The resulting hydrogen-bonding motif, which can be described by the graph set R₂²(8) (Etter, 1990 , 1991 ; Bernstein et al., 1995 ), is characteristic of primary carboxamides (Leiserowitz & Schmidt, 1969 ; Leiserowitz & Hagler, 1983 ; Aakeröy et al., 2007 ) and has been observed by us previously, e.g., for formamide molecules contained in the crystal structure of a solvate of 1-{[2,6-bis(hydroxymethyl)-4-methylphenoxy]methyl}-3,5-bis{[(4,6-dimethylpyridin-2-yl)amino]methyl}-2,4,6-triethylbenzene (Stapf et al., 2023 ). This motif is also found for isomorphous 2-chloroacetamide and in the structure of 2-fluoroacetamide. As in these, the dimers in the present structure are connected by N—H⋯O bonds to form a ladder-type network. Here, the carbonyl oxygen atom additionally interacts with the H1N atom of a neighbouring molecule [N1—H1N⋯O1, 2.29 (4) Å] and acts as a double acceptor for strong hydrogen bonds. This forms a further motif of the graph set R₄²(8), as depicted in Fig. 2. The association of the dimers is supported by C—H⋯Br contacts [d(H⋯Br) = 2.98 Å], whereas the layers are only linked to each other via C—H⋯O interactions [d(H⋯O) = 2.55 Å, see Table 1].

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N⋯Br1	0.82 (4)	2.69 (4)	3.120 (3)	115 (3)
N1—H1N⋯O1ⁱ	0.82 (4)	2.29 (4)	2.955 (4)	140 (4)
N1—H2N⋯O1ⁱⁱ	0.75 (5)	2.17 (5)	2.915 (5)	172 (5)
C2—H2B⋯Br1ⁱⁱⁱ	0.99	2.98	3.610 (3)	122
C2—H2A⋯O1^iv	0.99	2.55	3.462 (4)	153
Symmetry codes: (i) ; (ii) ; (iii) ; (iv) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Figure 1
Molecular structure of the title compound including the numbering scheme. Atoms are drawn with displacement ellipsoids at the 50% probability level. The intramolecular N—H⋯Br contact is shown as dashed line.

Figure 2
Excerpt of the crystal packing showing the R₂²(8) and R₄²(8) motifs of the N—H⋯O=C interactions, as well as the C—H⋯Br contact within one layer of amide molecules. These interactions are drawn as dashed lines.

Synthesis and crystallization

2-Bromoacetamide was used as purchased from Fluka. Single crystals suitable for X-ray analysis were obtained by crystallization from petroleum ether (boiling range 313–333 K) according to a literature known procedure for purification of the title compound (Halpern & Maher, 1965 ). ¹H NMR (500 MHz, DMSO-d₆, 298 K), δ: 3.81 (s, 2H, CH₂), 7.29 (br, 1H, NH), 7.66 (br, 1H, NH) p.p.m. ¹³C NMR (125 MHz, DMSO-d₆, 298 K), δ: 29.63 (CH₂), 167.92 (C=O) p.p.m. MS (ESI): m/z calcd. for C₂H₄BrNONa: 159.94 [M + Na]⁺, found 159.94.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₂H₄BrNO
M_r	137.97
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	93
a, b, c (Å)	10.373 (4), 5.1899 (14), 7.557 (3)
β (°)	99.94 (3)
V (Å³)	400.7 (3)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	10.06
Crystal size (mm)	0.11 × 0.09 × 0.04

Data collection
Diffractometer	Stoe Stadivari
Absorption correction	Multi-scan [X-RED32 (Stoe & Cie, 2023 ; Koziskova et al., 2016 )]
T_min, T_max	0.330, 0.668
No. of measured, independent and observed [I > 2σ(I)] reflections	4506, 879, 731
R_int	0.036
(sin θ/λ)_max (Å⁻¹)	0.638

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.028, 0.068, 1.04
No. of reflections	879
No. of parameters	52
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.58, −0.51
Computer programs: X-AREA (Stoe & Cie, 2023), SHELXT2018/2 (Sheldrick, 2015a ), SHELXL2019/2 (Sheldrick, 2015b ), XP (Sheldrick, 2008 ), WinGX (Farrugia, 2012 ), publCIF (Westrip, 2010 ) and ShelXle (Hübschle et al., 2011 ).

Structural data

CCDC reference: 2381424

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314624008630/bh4089sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314624008630/bh4089Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314624008630/bh4089Isup3.cml

checkCIF report

Computing details top

2-Bromoacetamide top

Crystal data top

C₂H₄BrNO	F(000) = 264
M_r = 137.97	D_x = 2.287 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 10.373 (4) Å	Cell parameters from 1778 reflections
b = 5.1899 (14) Å	θ = 1.7–22.5°
c = 7.557 (3) Å	µ = 10.06 mm⁻¹
β = 99.94 (3)°	T = 93 K
V = 400.7 (3) Å³	Plate, colorless
Z = 4	0.11 × 0.09 × 0.04 mm

Data collection top

Stoe Stadivari diffractometer	879 independent reflections
Radiation source: Primux 50 Mo	731 reflections with I > 2σ(I)
Graded multilayer mirror monochromator	R_int = 0.036
Detector resolution: 5.81 pixels mm^-1	θ_max = 27.0°, θ_min = 2.0°
rotation method, ω scans	h = −13→13
Absorption correction: multi-scan [X-Red32 (Stoe & Cie, 2023; Koziskova et al., 2016]	k = −6→6
T_min = 0.330, T_max = 0.668	l = −9→9
4506 measured reflections

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.028	Hydrogen site location: mixed
wR(F²) = 0.068	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	w = 1/[σ²(F_o²) + (0.0417P)² + 0.0569P] where P = (F_o² + 2F_c²)/3
879 reflections	(Δ/σ)_max = 0.001
52 parameters	Δρ_max = 0.58 e Å⁻³
0 restraints	Δρ_min = −0.51 e Å⁻³

Special details top

Refinement. The hydrogen atoms at N1 were located in a difference Fourier map and refined with free coordinates, and with the U_iso(H) values fixed at 1.5 times the equivalent U_eq value of the parent nitrogen atom (N1). The H atoms at the methylene carbon atom (C2) were included using a riding model with C—H = 0.99 Å, and the U_iso(H) values were fixed at 1.2 times the equivalent U_eq value of C2.

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

	x	y	z	U_iso*/U_eq
Br1	0.61180 (3)	0.82582 (6)	0.68653 (4)	0.01566 (15)
O1	0.8681 (3)	0.2945 (4)	0.5541 (3)	0.0181 (6)
N1	0.8855 (3)	0.7271 (6)	0.5813 (4)	0.0174 (7)
H1N	0.854 (4)	0.863 (7)	0.608 (6)	0.026*
H2N	0.950 (5)	0.735 (8)	0.550 (6)	0.026*
C1	0.8257 (3)	0.5060 (7)	0.5962 (4)	0.0140 (7)
C2	0.6997 (3)	0.4974 (6)	0.6709 (5)	0.0160 (7)
H2A	0.718682	0.421332	0.792727	0.019*
H2B	0.638276	0.380045	0.594915	0.019*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0141 (2)	0.0146 (2)	0.0191 (2)	0.00213 (14)	0.00526 (14)	0.00064 (14)
O1	0.0169 (14)	0.0129 (12)	0.0260 (15)	0.0002 (10)	0.0078 (12)	−0.0005 (10)
N1	0.0135 (16)	0.0153 (14)	0.0251 (18)	0.0008 (13)	0.0081 (14)	−0.0024 (13)
C1	0.0114 (18)	0.0167 (16)	0.0135 (16)	0.0029 (14)	0.0013 (13)	0.0034 (14)
C2	0.0147 (19)	0.0128 (15)	0.0216 (17)	0.0012 (15)	0.0063 (14)	0.0006 (15)

Geometric parameters (Å, º) top

Br1—C2	1.946 (3)	N1—H2N	0.75 (5)
O1—C1	1.244 (4)	C1—C2	1.512 (5)
N1—C1	1.318 (5)	C2—H2A	0.9900
N1—H1N	0.82 (4)	C2—H2B	0.9900

C1—N1—H1N	121 (3)	C1—C2—Br1	116.2 (2)
C1—N1—H2N	122 (3)	C1—C2—H2A	108.2
H1N—N1—H2N	117 (5)	Br1—C2—H2A	108.2
O1—C1—N1	123.7 (3)	C1—C2—H2B	108.2
O1—C1—C2	115.8 (3)	Br1—C2—H2B	108.2
N1—C1—C2	120.5 (3)	H2A—C2—H2B	107.4

O1—C1—C2—Br1	−166.7 (2)	N1—C1—C2—Br1	14.4 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···Br1	0.82 (4)	2.69 (4)	3.120 (3)	115 (3)
N1—H1N···O1ⁱ	0.82 (4)	2.29 (4)	2.955 (4)	140 (4)
N1—H2N···O1ⁱⁱ	0.75 (5)	2.17 (5)	2.915 (5)	172 (5)
C2—H2B···Br1ⁱⁱⁱ	0.99	2.98	3.610 (3)	122
C2—H2A···O1^iv	0.99	2.55	3.462 (4)	153

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

Acknowledgements

The authors would like to thank Professor Dr Monika Mazik (Technische Universität Bergakademie Freiberg) for her general support.

Funding information

Funding for this research was provided by: Open Access Funding by the Publication Fund of the TU Bergakademie Freiberg.

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