2-(2-Acetamido-5-methyl­benzo­yl)-1H-indole

In the title compound, C₁₈H₁₆N₂O₂, the dihedral angle between the indole ring system and the benzoyl benzene ring is 31.5 (1)°. In the crystalline state, symmetry-related mol­ecules are linked via N—H...O and C—H...O hydrogen bonds, and π–π inter­actions to form a layer structure parallel to the bc plane.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.077
• wR factor = 0.216
• Data-to-parameter ratio = 15.5

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT601_ALERT_2_A Structure Contains Solvent Accessible VOIDS of .     374.00 A   3  

Author Response: Please refer _publ_section_exptl_refinement.

Alert level C
PLAT199_ALERT_1_C Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_C Check the Reported _diffrn_ambient_temperature .        293 K
PLAT340_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          5
PLAT380_ALERT_4_C Check Incorrectly? Oriented X(sp2)-Methyl Moiety        C16

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

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

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S1. Comment

Many idole derivatives, both natural and synthetic, show important biological activities such as antibacterial, antifungal (Wang & Ng, 2002; Singh et al., 2000; Tsotinis et al., 1997; Quetin-Leclercq et al., 1995), antitumour (Andreani et al., 2001; Bradlow et al., 1999; Cirrincione et al., 1999; Tiwari et al., 1994; Dashwood et al., 1994) and antimicrobial activities (Piscopo, Diurno, Mazzoni & Ciaccio, 1990; Piscopo, Diurno, Mazzoni, Ciaccio & Veneruso, 1990). Some indole derivatives are used as neuroprotectants (Stolc, 1999). Recently, we have reported the crystal structures of some phenylsulfonylindole derivatives (Ravishankar et al., 2003a,b, 2005a,b). We report here the crystal structure of the title compound, (I).

The indole ring system in (I) (Fig. 1) is planar, with a maximum deviation of 0.017 (3) Å for atom C2. The N—Csp² bond lengths, viz. N1—C1 [1.377 (4) Å] and N1—C8 [1.369 (4) Å], are comparable with the mean value of 1.355 (14) Å reported for N atoms with planar configurations (Allen et al., 1987). These values are significantly longer in phenylsulfonyl indole derivatives (Ravishankar et al., 2003a,b, Ravishankar et al., 2005a,b). The conformation of the attachment of the benzoyl substituent to the indole ring system is described by the C2—C1—C9—C10 torsion angle of 7.2 (5)°; the C1—C9—C10—C11 torsion angle of 28.2 (4)° shows how the C10–C15 ring is oriented. The mean plane through the acetylamide group makes a dihedral angle of 15.1 (2)° with the C10–C15 ring. This orientation is influenced by the intramolecular N2—H2N···O1 and C14—H14···O2 hydrogen bonds involving carbonyl atoms O1 and O2 (Table 1). Each of these interactions generates rings of graph-set motif S(6) (Bernstein et al., 1995; Etter, 1990).

The packing of the molecules, shown in Fig. 2, reveals that symmetry-related molecules are linked via N—H···O and C—H···O hydrogen bonds to form a layer structure parallel to the bc plane. Within a layer, the C10–C15 benzene rings at the symmetry positions (x, y, z) and (1/2 − x, 1/2 − y, 1 − z) are stacked with their centroids 3.688 (2) Å apart, indicating the presence of π–π interactions.

S2. Experimental

A solution of 1-phenylsulfonyl-2-(2-acetamido-5-methylbenzoyl)indole (5 mmol) in methanol (100 mmol) was refluxed with 10% sodium hydroxide solution (10 ml) for 30 min. The solution was poured over ice and the precipitated solid was filtered off, washed with water, dried over anhydrous calcium chloride and purified by crystallization. Single crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of a methanol solution.

S3. Refinement

H atoms were positioned geometrically and treated as riding on their parent atoms, with an N—H distance of 0.86 Å, C—H distances of 0.93 (aromatic) and 0.96 Å (methyl), and with U_iso(H) = 1.5U_eq(methyl C) and 1.2U_eq(other atoms). A rotating group model was used for the methyl groups. The refinement converged to an R value of 0.095 (wR = 0.248) and the difference map showed three highest peaks of 0.81, 0.51 and 0.48 e Å⁻³. Refinement based on a disordered solvent model led to unstable refinement with very high displacement parameters. A search for solvent-accessible voids in the crystal structure using PLATON (Spek, 2003) showed a potential solvent volume of 746.1 ų and subsequent application of SQUEEZE procedures (Sluis & Spek, 1990) showed only one relevant void with a solvent-accessible volume of 373 ų. However, this procedure showed no electrons in the void as the weak positive and negative density excursions in the void region sum close to zero. This indicates that the crystal lost nearly all of its solvent of crystallization by the time it was used for data collection, without collapse of the structure. Further refinement of the structure with data obtained from the above procedure converged to an R value of 0.077 (wR = 0.216). The limited improvement of R values indicates that there are still residual problems associated with the data. As no more crystals were available, we were unable to repeat the experiment at a lower temperature, on a crystal freshly chosen from the mother liquor.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003).

Figures

	Fig. 1. The structure of (I), showing the atom-numbering scheme and intramolecular hydrogen bonds (as dashed lines). Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. A view of the N—H···O and C—H···O hydrogen-bonded layers in (I). Hydrogen bonds are shown as dashed lines.

2-(2-Acetamido-5-methylbenzoyl)indole

Crystal data

C18H16N2O2	F(000) = 1232
Mr = 292.33	Dx = 1.098 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 2509 reflections
a = 21.8765 (12) Å	θ = 2.3–28.3°
b = 14.3774 (8) Å	µ = 0.07 mm^−1
c = 11.7603 (7) Å	T = 293 K
β = 107.050 (1)°	Block, colourless
V = 3536.4 (3) Å^3	0.36 × 0.20 × 0.10 mm
Z = 8

Data collection

Siemens SMART CCD area-detector diffractometer	2067 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.041
Graphite monochromator	θmax = 25.0°, θmin = 2.3°
Detector resolution: 8.33 pixels mm^-1	h = −26→26
ω scans	k = −17→9
8691 measured reflections	l = −13→13
3108 independent reflections

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)] = 0.077	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.216	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.1234P)^2 + 0.2753P] where P = (Fo^2 + 2Fc^2)/3
3108 reflections	(Δ/σ)max = 0.001
201 parameters	Δρmax = 0.27 e Å^−3
0 restraints	Δρmin = −0.25 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
O1	0.24259 (12)	−0.00154 (16)	0.3462 (2)	0.0524 (7)
O2	0.34245 (13)	0.28941 (17)	0.2779 (2)	0.0543 (7)
N1	0.14819 (12)	−0.08089 (17)	0.4111 (2)	0.0356 (7)
H1N	0.1565	−0.1067	0.3514	0.043*
N2	0.30328 (13)	0.15428 (19)	0.3295 (2)	0.0422 (7)
H2N	0.2858	0.1028	0.2995	0.051*
C1	0.18169 (14)	−0.0079 (2)	0.4763 (2)	0.0304 (7)
C2	0.15435 (15)	0.0146 (2)	0.5644 (3)	0.0346 (8)
H2	0.1674	0.0619	0.6203	0.042*
C3	0.10267 (15)	−0.0478 (2)	0.5542 (3)	0.0356 (8)
C4	0.05740 (17)	−0.0600 (3)	0.6168 (3)	0.0506 (10)
H4	0.0581	−0.0225	0.6817	0.061*
C5	0.01238 (17)	−0.1282 (3)	0.5803 (4)	0.0607 (11)
H5	−0.0174	−0.1374	0.6216	0.073*
C6	0.01010 (17)	−0.1845 (3)	0.4820 (4)	0.0596 (11)
H6	−0.0215	−0.2297	0.4591	0.072*
C7	0.05319 (16)	−0.1745 (3)	0.4189 (3)	0.0477 (9)
H7	0.0515	−0.2120	0.3536	0.057*
C8	0.09963 (14)	−0.1060 (2)	0.4564 (3)	0.0354 (8)
C9	0.23494 (15)	0.0302 (2)	0.4387 (3)	0.0337 (7)
C10	0.27804 (14)	0.1041 (2)	0.5082 (3)	0.0309 (7)
C11	0.28902 (15)	0.1123 (2)	0.6301 (3)	0.0375 (8)
H11	0.2698	0.0696	0.6682	0.045*
C12	0.32714 (15)	0.1807 (2)	0.6976 (3)	0.0397 (8)
C13	0.35524 (16)	0.2434 (3)	0.6376 (3)	0.0455 (9)
H13	0.3802	0.2916	0.6798	0.055*
C14	0.34708 (16)	0.2359 (2)	0.5181 (3)	0.0404 (8)
H14	0.3668	0.2787	0.4810	0.049*
C15	0.31024 (14)	0.1661 (2)	0.4515 (3)	0.0328 (7)
C16	0.3385 (2)	0.1880 (3)	0.8305 (3)	0.0684 (13)
H16A	0.3153	0.1397	0.8562	0.103*
H16B	0.3240	0.2476	0.8492	0.103*
H16C	0.3833	0.1815	0.8705	0.103*
C17	0.31985 (16)	0.2116 (2)	0.2520 (3)	0.0401 (8)
C18	0.3090 (2)	0.1711 (3)	0.1300 (3)	0.0627 (12)
H18A	0.3190	0.2168	0.0787	0.094*
H18B	0.2650	0.1529	0.0987	0.094*
H18C	0.3359	0.1176	0.1347	0.094*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0813 (18)	0.0481 (16)	0.0425 (14)	−0.0239 (13)	0.0408 (13)	−0.0165 (11)
O2	0.0867 (19)	0.0450 (16)	0.0373 (14)	−0.0184 (14)	0.0277 (13)	−0.0002 (11)
N1	0.0461 (16)	0.0346 (16)	0.0305 (14)	−0.0059 (12)	0.0178 (12)	−0.0061 (12)
N2	0.0648 (19)	0.0363 (16)	0.0317 (14)	−0.0183 (14)	0.0238 (13)	−0.0048 (12)
C1	0.0393 (17)	0.0247 (17)	0.0273 (16)	−0.0015 (13)	0.0101 (14)	−0.0024 (12)
C2	0.0430 (18)	0.0300 (17)	0.0325 (17)	−0.0028 (14)	0.0135 (14)	−0.0060 (13)
C3	0.0386 (18)	0.0382 (19)	0.0303 (16)	0.0066 (14)	0.0104 (13)	0.0040 (14)
C4	0.049 (2)	0.064 (3)	0.044 (2)	0.0033 (19)	0.0221 (17)	0.0002 (18)
C5	0.041 (2)	0.078 (3)	0.069 (3)	−0.006 (2)	0.0249 (19)	0.012 (2)
C6	0.040 (2)	0.065 (3)	0.073 (3)	−0.0169 (19)	0.014 (2)	−0.001 (2)
C7	0.042 (2)	0.047 (2)	0.049 (2)	−0.0044 (17)	0.0066 (16)	−0.0042 (17)
C8	0.0362 (17)	0.0360 (18)	0.0311 (17)	−0.0026 (14)	0.0053 (13)	0.0025 (14)
C9	0.0476 (19)	0.0300 (18)	0.0261 (16)	−0.0022 (14)	0.0147 (14)	0.0023 (13)
C10	0.0377 (17)	0.0290 (17)	0.0290 (16)	0.0020 (13)	0.0147 (13)	0.0043 (13)
C11	0.0432 (19)	0.044 (2)	0.0273 (16)	−0.0054 (15)	0.0131 (14)	0.0043 (14)
C12	0.0416 (18)	0.053 (2)	0.0237 (16)	−0.0070 (16)	0.0088 (14)	−0.0012 (15)
C13	0.049 (2)	0.049 (2)	0.0385 (19)	−0.0163 (17)	0.0123 (16)	−0.0106 (16)
C14	0.047 (2)	0.043 (2)	0.0328 (18)	−0.0119 (16)	0.0153 (15)	0.0021 (15)
C15	0.0394 (17)	0.0320 (18)	0.0299 (16)	0.0012 (14)	0.0144 (14)	0.0025 (14)
C16	0.077 (3)	0.095 (3)	0.032 (2)	−0.031 (2)	0.0137 (19)	−0.012 (2)
C17	0.050 (2)	0.044 (2)	0.0316 (18)	−0.0096 (17)	0.0192 (15)	0.0022 (15)
C18	0.098 (3)	0.061 (3)	0.038 (2)	−0.026 (2)	0.034 (2)	−0.0088 (18)

Geometric parameters (Å, º)

O1—C9	1.235 (3)	C7—C8	1.391 (4)
O2—C17	1.225 (4)	C7—H7	0.93
N1—C8	1.369 (4)	C9—C10	1.495 (4)
N1—C1	1.377 (4)	C10—C11	1.387 (4)
N1—H1N	0.86	C10—C15	1.418 (4)
N2—C17	1.355 (4)	C11—C12	1.380 (4)
N2—C15	1.408 (4)	C11—H11	0.93
N2—H2N	0.86	C12—C13	1.394 (4)
C1—C2	1.379 (4)	C12—C16	1.513 (4)
C1—C9	1.468 (4)	C13—C14	1.367 (4)
C2—C3	1.420 (4)	C13—H13	0.93
C2—H2	0.93	C14—C15	1.379 (4)
C3—C8	1.408 (4)	C14—H14	0.93
C3—C4	1.408 (5)	C16—H16A	0.96
C4—C5	1.367 (5)	C16—H16B	0.96
C4—H4	0.93	C16—H16C	0.96
C5—C6	1.399 (5)	C17—C18	1.501 (4)
C5—H5	0.93	C18—H18A	0.96
C6—C7	1.368 (5)	C18—H18B	0.96
C6—H6	0.93	C18—H18C	0.96
C8—N1—C1	109.4 (2)	C11—C10—C15	118.2 (3)
C8—N1—H1N	125.3	C11—C10—C9	121.1 (3)
C1—N1—H1N	125.3	C15—C10—C9	120.7 (3)
C17—N2—C15	129.9 (3)	C12—C11—C10	123.2 (3)
C17—N2—H2N	115.0	C12—C11—H11	118.4
C15—N2—H2N	115.0	C10—C11—H11	118.4
N1—C1—C2	108.6 (3)	C11—C12—C13	116.8 (3)
N1—C1—C9	117.2 (2)	C11—C12—C16	122.2 (3)
C2—C1—C9	134.2 (3)	C13—C12—C16	121.0 (3)
C1—C2—C3	107.3 (3)	C14—C13—C12	121.7 (3)
C1—C2—H2	126.3	C14—C13—H13	119.2
C3—C2—H2	126.3	C12—C13—H13	119.2
C8—C3—C4	118.7 (3)	C13—C14—C15	121.3 (3)
C8—C3—C2	106.9 (3)	C13—C14—H14	119.3
C4—C3—C2	134.3 (3)	C15—C14—H14	119.3
C5—C4—C3	118.5 (3)	C14—C15—N2	122.5 (3)
C5—C4—H4	120.7	C14—C15—C10	118.6 (3)
C3—C4—H4	120.7	N2—C15—C10	118.9 (3)
C4—C5—C6	121.5 (3)	C12—C16—H16A	109.5
C4—C5—H5	119.2	C12—C16—H16B	109.5
C6—C5—H5	119.2	H16A—C16—H16B	109.5
C7—C6—C5	121.6 (3)	C12—C16—H16C	109.5
C7—C6—H6	119.2	H16A—C16—H16C	109.5
C5—C6—H6	119.2	H16B—C16—H16C	109.5
C6—C7—C8	117.2 (3)	O2—C17—N2	123.8 (3)
C6—C7—H7	121.4	O2—C17—C18	122.1 (3)
C8—C7—H7	121.4	N2—C17—C18	114.1 (3)
N1—C8—C7	129.9 (3)	C17—C18—H18A	109.5
N1—C8—C3	107.7 (3)	C17—C18—H18B	109.5
C7—C8—C3	122.4 (3)	H18A—C18—H18B	109.5
O1—C9—C1	116.9 (3)	C17—C18—H18C	109.5
O1—C9—C10	121.2 (3)	H18A—C18—H18C	109.5
C1—C9—C10	122.0 (3)	H18B—C18—H18C	109.5
C8—N1—C1—C2	−0.1 (3)	C2—C1—C9—C10	7.2 (5)
C8—N1—C1—C9	−178.5 (3)	O1—C9—C10—C11	−152.0 (3)
N1—C1—C2—C3	0.8 (3)	C1—C9—C10—C11	28.2 (4)
C9—C1—C2—C3	178.8 (3)	O1—C9—C10—C15	26.2 (5)
C1—C2—C3—C8	−1.2 (3)	C1—C9—C10—C15	−153.6 (3)
C1—C2—C3—C4	179.9 (4)	C15—C10—C11—C12	3.4 (5)
C8—C3—C4—C5	0.1 (5)	C9—C10—C11—C12	−178.4 (3)
C2—C3—C4—C5	178.9 (4)	C10—C11—C12—C13	0.0 (5)
C3—C4—C5—C6	−0.8 (6)	C10—C11—C12—C16	−179.9 (3)
C4—C5—C6—C7	0.7 (6)	C11—C12—C13—C14	−2.0 (5)
C5—C6—C7—C8	0.0 (6)	C16—C12—C13—C14	177.9 (4)
C1—N1—C8—C7	178.9 (3)	C12—C13—C14—C15	0.4 (6)
C1—N1—C8—C3	−0.6 (3)	C13—C14—C15—N2	−177.2 (3)
C6—C7—C8—N1	179.9 (3)	C13—C14—C15—C10	3.0 (5)
C6—C7—C8—C3	−0.7 (5)	C17—N2—C15—C14	−11.9 (5)
C4—C3—C8—N1	−179.8 (3)	C17—N2—C15—C10	167.9 (3)
C2—C3—C8—N1	1.1 (3)	C11—C10—C15—C14	−4.8 (4)
C4—C3—C8—C7	0.6 (5)	C9—C10—C15—C14	176.9 (3)
C2—C3—C8—C7	−178.5 (3)	C11—C10—C15—N2	175.4 (3)
N1—C1—C9—O1	5.3 (4)	C9—C10—C15—N2	−2.8 (4)
C2—C1—C9—O1	−172.6 (3)	C15—N2—C17—O2	−3.5 (6)
N1—C1—C9—C10	−174.9 (3)	C15—N2—C17—C18	175.7 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O2^i	0.86	2.14	2.954 (3)	159
N2—H2N···O1	0.86	1.94	2.641 (4)	138
C2—H2···O2^ii	0.93	2.49	3.363 (4)	156
C11—H11···O1^iii	0.93	2.53	3.397 (4)	154
C14—H14···O2	0.93	2.29	2.901 (4)	122
C16—H16A···O1^iii	0.96	2.53	3.442 (5)	160

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