N-(2,5-Dichloro­phen­yl)acetamide

The conformation of the N—H bond in the title compound, C₈H₇Cl₂NO, is syn to the ortho-chloro group and anti to the meta-chloro group, in contrast to the syn conformation observed with respect to both ortho- and meta-chloro substituents in N-(2,3-dichloro­phen­yl)acetamide and the anti conformation with respect to the meta-chloro substituent in N-(3,4-dichloro­phen­yl)acetamide. The dihedral angle between the dichloro­phenyl and acetamide groups is 44.6 (2)°. Short Cl...Cl type II contacts (Cl...Cl = 3.5 Å) and inter­molecular N—H...O hydrogen bonds link the mol­ecules into chains.

Key indicators

• Single-crystal X-ray study
• T = 299 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.055
• wR factor = 0.108
• Data-to-parameter ratio = 14.0

checkCIF/PLATON results

No syntax errors found



Alert level A
RINTA01_ALERT_3_A  The value of Rint is greater than 0.20
            Rint given   0.213

Author Response: The structure is an organic compound, which scatters with minor intensity at high theta value and this has resulted in a higher than normal for R~int~(0.213).

PLAT020_ALERT_3_A The value of Rint is greater than 0.10 .........       0.21

Author Response: The structure is of an organic compound, which scatters with minor intensity at high theta value and this has resulted in a higher than normal.

Alert level C
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          6

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

   2 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The amide moiety is an important constituent of many biologically significant compounds. The structural studies of amides are therefore of interest (Gowda et al., 2007a,b; Gowda, Kozisek et al., 2007, and references therein; Jones et al., 1990; Wan et al., 2006). As part of a study of the effect of ring and side chain substitutions on the solid state structures of this class of compounds (Gowda et al., 2007a,b; Gowda, Kozisek et al., 2007, and references therein), the crystal structure of N-(2,5-dichlorophenyl)-acetamide (25DCPA) has been determined. The conformation of the N—H bond in 25DCPA is syn to the ortho chloro group and anti to the meta chloro group (Fig. 1), in contrast to the syn conformation observed with respect to both ortho and meta chloro substituents in N-(2,3-dichlorophenyl)-acetamide (Gowda et al., 2007b) and anti conformation observed with respect to the meta chloro substituent in N-(3,4-dichlorophenyl)-acetamide (Jones et al., 1990). The bond lengths and angles in 25DCPA show normal values (Allen et al., 1987). The molecular skeleton is essentially planar. The dihedral angle between the mean planes of the dichlorophenyl and the acetamide moiety is 44.6 (2) °. The intermolecular N—H···O hydrogen bonds (Table 1) link the molecules into chains (Fig. 2). Further, a short ClA···Cl Type II contact (distance = 3.5 Å) controls the packing in the structure.

Related literature

For related literature, see: Allen et al. (1987); Gowda et al. (2007a,b); Gowda, Kozisek et al. (2007, and references therein); Jones et al. (1990); Pies et al. (1971); Shilpa & Gowda (2007); Wan et al. (2006).

S2. Experimental

The title compound was prepared according to the literature method of Shilpa and Gowda (Shilpa & Gowda, 2007). The purity of the compound was checked by determining its melting point. It was characterized by recording its infrared, NMR (Shilpa & Gowda, 2007) and NQR spectra (Pies et al., 1971). Single crystals of the title compound were obtained from a slow evaporation of its ethanolic solution (2 g in about 30 ml e thanol) and used for X-ray diffraction studies at room temperature.

S3. Refinement

All H atoms attached to C atoms were fixed geometrically and treated as riding with C–H = 0.93 Å (CH aromatic) or 0.96 Å (CH₃) and U_iso(H) = 1.5 U_eq(CH₃). N—H distance was restrained to 0.86 (1) Å.

Computing details

Data collection: CAD-4-PC (Enraf–Nonius, 1996); cell refinement: CAD-4-PC; data reduction: REDU4 (Stoe & Cie, 1987); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. Molecular structure of the title compound showing the atom labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented as small spheres of arbitrary radii.
	Fig. 2. Crystal packing of the title compound. Hydrogen bonds are shown as dashed lines.

N-(2,5-Dichlorophenyl)acetamide

Crystal data

C8H7Cl2NO	F(000) = 416
Mr = 204.05	Dx = 1.517 Mg m^−3
Monoclinic, P21/n	Cu Kα radiation, λ = 1.54180 Å
Hall symbol: -P 2yn	Cell parameters from 25 reflections
a = 5.8557 (4) Å	θ = 5.6–25.3°
b = 4.7942 (4) Å	µ = 6.13 mm^−1
c = 31.822 (2) Å	T = 299 K
β = 90.531 (6)°	Prism, white
V = 893.31 (11) Å^3	0.15 × 0.10 × 0.03 mm
Z = 4

Data collection

Enraf–Nonius CAD-4 diffractometer	1017 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.213
Graphite monochromator	θmax = 66.9°, θmin = 2.8°
ω/2θ scans	h = −6→6
Absorption correction: ψ scan (North et al., 1968)	k = −5→1
Tmin = 0.478, Tmax = 0.832	l = −37→37
3583 measured reflections	3 standard reflections every 120 min
1569 independent reflections	intensity decay: 1.0%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.055	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.108	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ^2(Fo^2)]
1569 reflections	(Δ/σ)max < 0.001
112 parameters	Δρmax = 0.29 e Å^−3
1 restraint	Δρmin = −0.48 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
C1	0.2319 (10)	0.7304 (5)	0.01550 (14)	0.058 (2)
H1A	0.1171	0.5979	0.0234	0.069*
H1B	0.3502	0.6368	0.0003	0.069*
H1C	0.1643	0.8718	−0.0020	0.069*
C2	0.3318 (8)	0.8623 (5)	0.05414 (13)	0.0379 (12)
C5	0.5242 (9)	0.7740 (5)	0.12195 (12)	0.0357 (12)
C6	0.7266 (8)	0.6682 (5)	0.13610 (12)	0.0395 (12)
C7	0.8178 (9)	0.7474 (6)	0.17467 (15)	0.0468 (14)
H7	0.9556	0.6719	0.1840	0.056*
C8	0.7039 (9)	0.9384 (6)	0.19928 (14)	0.0459 (14)
H8	0.7638	0.9938	0.2251	0.055*
C9	0.5013 (9)	1.0442 (5)	0.18487 (13)	0.0396 (12)
C10	0.4075 (9)	0.9656 (5)	0.14680 (13)	0.0386 (12)
H10	0.2685	1.0392	0.1378	0.046*
N4	0.4305 (7)	0.6906 (4)	0.08251 (10)	0.0371 (10)
H4N	0.424 (7)	0.522 (3)	0.0752 (12)	0.045*
O3	0.3239 (7)	1.1152 (3)	0.05928 (9)	0.0610 (13)
Cl11	0.8771 (2)	0.43003 (17)	0.10588 (4)	0.0553 (4)
Cl12	0.3522 (2)	1.28471 (15)	0.21550 (3)	0.0535 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.090 (5)	0.0300 (13)	0.053 (3)	0.0036 (19)	−0.022 (3)	−0.0087 (15)
C2	0.043 (4)	0.0297 (12)	0.041 (3)	−0.0012 (17)	−0.001 (2)	0.0017 (15)
C5	0.038 (3)	0.0292 (12)	0.040 (3)	−0.0044 (15)	−0.007 (2)	0.0057 (14)
C6	0.036 (3)	0.0314 (13)	0.052 (3)	0.0000 (17)	0.001 (2)	0.0075 (15)
C7	0.041 (4)	0.0488 (16)	0.051 (3)	0.002 (2)	−0.007 (3)	0.0082 (18)
C8	0.045 (4)	0.0496 (17)	0.043 (3)	−0.004 (2)	−0.011 (2)	0.0026 (18)
C9	0.048 (4)	0.0286 (13)	0.043 (3)	−0.0049 (17)	0.000 (2)	0.0020 (14)
C10	0.042 (3)	0.0298 (12)	0.044 (3)	0.0028 (17)	−0.001 (2)	0.0013 (15)
N4	0.043 (3)	0.0235 (10)	0.045 (2)	0.0026 (14)	−0.0064 (18)	−0.0024 (11)
O3	0.108 (4)	0.0222 (8)	0.052 (2)	0.0035 (14)	−0.015 (2)	−0.0009 (11)
Cl11	0.0448 (10)	0.0533 (5)	0.0679 (9)	0.0153 (5)	0.0043 (6)	−0.0026 (5)
Cl12	0.0659 (12)	0.0473 (4)	0.0474 (8)	0.0051 (5)	0.0033 (6)	−0.0066 (4)

Geometric parameters (Å, º)

C1—C2	1.497 (4)	C6—Cl11	1.738 (5)
C1—H1A	0.9600	C7—C8	1.381 (7)
C1—H1B	0.9600	C7—H7	0.9300
C1—H1C	0.9600	C8—C9	1.366 (6)
C2—O3	1.225 (3)	C8—H8	0.9300
C2—N4	1.348 (4)	C9—C10	1.378 (5)
C5—C6	1.362 (5)	C9—Cl12	1.748 (5)
C5—C10	1.395 (6)	C10—H10	0.9300
C5—N4	1.423 (4)	N4—H4N	0.841 (10)
C6—C7	1.387 (5)
C2—C1—H1A	109.5	C8—C7—C6	120.0 (4)
C2—C1—H1B	109.5	C8—C7—H7	120.0
H1A—C1—H1B	109.5	C6—C7—H7	120.0
C2—C1—H1C	109.5	C9—C8—C7	118.6 (3)
H1A—C1—H1C	109.5	C9—C8—H8	120.7
H1B—C1—H1C	109.5	C7—C8—H8	120.7
O3—C2—N4	122.1 (3)	C8—C9—C10	122.1 (4)
O3—C2—C1	120.9 (3)	C8—C9—Cl12	119.6 (3)
N4—C2—C1	117.0 (2)	C10—C9—Cl12	118.3 (4)
C6—C5—C10	119.1 (3)	C9—C10—C5	119.0 (4)
C6—C5—N4	121.0 (4)	C9—C10—H10	120.5
C10—C5—N4	119.9 (4)	C5—C10—H10	120.5
C5—C6—C7	121.2 (4)	C2—N4—C5	125.3 (2)
C5—C6—Cl11	120.4 (3)	C2—N4—H4N	113 (2)
C7—C6—Cl11	118.4 (3)	C5—N4—H4N	122 (2)
C10—C5—C6—C7	0.1 (6)	C8—C9—C10—C5	−0.7 (7)
N4—C5—C6—C7	−179.5 (4)	Cl12—C9—C10—C5	180.0 (3)
C10—C5—C6—Cl11	−179.8 (3)	C6—C5—C10—C9	0.5 (6)
N4—C5—C6—Cl11	0.6 (6)	N4—C5—C10—C9	−179.9 (4)
C5—C6—C7—C8	−0.5 (7)	O3—C2—N4—C5	3.6 (8)
Cl11—C6—C7—C8	179.3 (3)	C1—C2—N4—C5	−176.7 (5)
C6—C7—C8—C9	0.4 (7)	C6—C5—N4—C2	−137.7 (5)
C7—C8—C9—C10	0.2 (7)	C10—C5—N4—C2	42.7 (7)
C7—C8—C9—Cl12	179.6 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4N···O3^i	0.84 (1)	2.10 (1)	2.921 (3)	166 (4)

Symmetry code: (i) x, y−1, z.