The crystal structure of the title compound, C
10H
13NO, displays an infinite one-dimensional network composed of primary amide molecules connected by N—H
O=C hydrogen bonds involving the
anti NH amide H atoms, thus generating a
C(4) motif. This network is additionally stabilized by a weak N—H
π interaction between the
syn-oriented amide H atom and the aromatic ring of a neighbouring molecule. The distance between the H atom and the ring centroid is 2.50 Å. The amide group and the aryl moiety are nearly perpendicular, forming an intramolecular dihedral angle of 84.69 (6)°.
Supporting information
CCDC reference: 231065
The title compound was obtained by reaction of 2,4,6-trimethylbenzoylamide with aqueous ammonia [m.p. 461–462 K (toluene–hexane); literature m.p. 462 K (Hantzsch & Lucas, 1895)].
All H atoms were located from difference maps. H-atom distances were standarized to 0.90 and 0.96 Å for N—H and C—H bonds, respectively. Their isotropic displacement parameters were allowed to refine.
Data collection: CrysAlis (Oxford Diffraction, 2000); cell refinement: CrysAlis; data reduction: CrysAlis; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Stereochemical Workstation (Siemens, 1989); software used to prepare material for publication: SHELXL97.
2,4,6-trimethylbenzamide
top
Crystal data top
C10H13NO | Dx = 1.193 Mg m−3 |
Mr = 163.21 | Melting point = 188–189 K |
Orthorhombic, Pbca | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P2ac2ab | Cell parameters from 3457 reflections |
a = 14.2587 (9) Å | θ = 4–25° |
b = 8.5369 (6) Å | µ = 0.08 mm−1 |
c = 14.9245 (10) Å | T = 130 K |
V = 1816.7 (2) Å3 | Plate, colorless |
Z = 8 | 0.22 × 0.15 × 0.02 mm |
F(000) = 704 | |
Data collection top
Kuma KM4CCD κ geometry diffractometer | 1096 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.049 |
Graphite monochromator | θmax = 25.0°, θmin = 3.1° |
ω scans | h = −9→16 |
8742 measured reflections | k = −9→10 |
1597 independent reflections | l = −17→17 |
Refinement top
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)] = 0.043 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.090 | H-atom parameters constrained |
S = 1.03 | w = 1/[σ2(Fo2) + (0.0363P)2] where P = (Fo2 + 2Fc2)/3 |
1597 reflections | (Δ/σ)max < 0.001 |
122 parameters | Δρmax = 0.13 e Å−3 |
0 restraints | Δρmin = −0.18 e Å−3 |
Crystal data top
C10H13NO | V = 1816.7 (2) Å3 |
Mr = 163.21 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 14.2587 (9) Å | µ = 0.08 mm−1 |
b = 8.5369 (6) Å | T = 130 K |
c = 14.9245 (10) Å | 0.22 × 0.15 × 0.02 mm |
Data collection top
Kuma KM4CCD κ geometry diffractometer | 1096 reflections with I > 2σ(I) |
8742 measured reflections | Rint = 0.049 |
1597 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.043 | 0 restraints |
wR(F2) = 0.090 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.13 e Å−3 |
1597 reflections | Δρmin = −0.18 e Å−3 |
122 parameters | |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.07442 (9) | 1.09643 (15) | 0.28709 (10) | 0.0477 (5) | |
N1 | −0.01773 (10) | 0.91868 (19) | 0.21771 (11) | 0.0326 (4) | |
H1N | −0.0366 | 0.8183 | 0.2140 | 0.047 (6)* | |
H2N | −0.0443 | 0.9928 | 0.1831 | 0.062 (7)* | |
C1 | 0.08180 (12) | 0.8329 (2) | 0.33840 (12) | 0.0226 (5) | |
C2 | 0.03201 (12) | 0.7952 (2) | 0.41598 (13) | 0.0242 (5) | |
C3 | 0.06867 (13) | 0.6821 (2) | 0.47347 (13) | 0.0257 (5) | |
H3 | 0.0354 | 0.6566 | 0.5275 | 0.022 (5)* | |
C4 | 0.15280 (13) | 0.6063 (2) | 0.45542 (12) | 0.0236 (5) | |
C5 | 0.20051 (13) | 0.6449 (2) | 0.37735 (13) | 0.0245 (5) | |
H5 | 0.2585 | 0.5917 | 0.3654 | 0.023 (5)* | |
C6 | 0.16641 (12) | 0.7571 (2) | 0.31800 (12) | 0.0239 (5) | |
C7 | 0.04581 (12) | 0.9604 (2) | 0.27857 (14) | 0.0293 (5) | |
C8 | −0.06077 (12) | 0.8729 (2) | 0.43627 (14) | 0.0339 (6) | |
H81 | −0.0789 | 0.8531 | 0.4972 | 0.038 (6)* | |
H82 | −0.0571 | 0.9834 | 0.4247 | 0.040 (6)* | |
H83 | −0.1093 | 0.8282 | 0.3998 | 0.041 (6)* | |
C9 | 0.19166 (14) | 0.4845 (2) | 0.51830 (14) | 0.0347 (6) | |
H91 | 0.1490 | 0.4597 | 0.5660 | 0.069 (8)* | |
H92 | 0.2042 | 0.3876 | 0.4879 | 0.063 (7)* | |
H93 | 0.2506 | 0.5135 | 0.5446 | 0.074 (8)* | |
C10 | 0.21870 (14) | 0.7935 (2) | 0.23223 (13) | 0.0353 (6) | |
H101 | 0.2330 | 0.9033 | 0.2288 | 0.075 (8)* | |
H102 | 0.2751 | 0.7322 | 0.2297 | 0.060 (7)* | |
H103 | 0.1822 | 0.7610 | 0.1815 | 0.063 (8)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0406 (9) | 0.0211 (8) | 0.0814 (12) | −0.0074 (7) | −0.0240 (8) | 0.0106 (8) |
N1 | 0.0354 (10) | 0.0228 (10) | 0.0396 (11) | 0.0015 (8) | −0.0116 (9) | 0.0050 (9) |
C1 | 0.0213 (10) | 0.0169 (10) | 0.0296 (12) | −0.0025 (8) | −0.0051 (9) | −0.0013 (9) |
C2 | 0.0215 (11) | 0.0199 (11) | 0.0313 (12) | −0.0023 (8) | −0.0021 (9) | −0.0053 (9) |
C3 | 0.0294 (12) | 0.0250 (11) | 0.0227 (11) | −0.0058 (9) | 0.0021 (9) | −0.0021 (9) |
C4 | 0.0250 (11) | 0.0215 (11) | 0.0241 (11) | −0.0031 (9) | −0.0064 (9) | −0.0024 (9) |
C5 | 0.0205 (11) | 0.0206 (11) | 0.0325 (12) | 0.0022 (9) | −0.0019 (9) | −0.0029 (10) |
C6 | 0.0239 (11) | 0.0209 (10) | 0.0269 (11) | −0.0030 (9) | −0.0015 (9) | −0.0009 (9) |
C7 | 0.0209 (11) | 0.0258 (11) | 0.0411 (13) | −0.0001 (9) | −0.0025 (10) | 0.0028 (10) |
C8 | 0.0245 (12) | 0.0329 (13) | 0.0443 (16) | −0.0005 (10) | 0.0015 (11) | −0.0023 (10) |
C9 | 0.0379 (14) | 0.0317 (13) | 0.0344 (13) | 0.0005 (11) | −0.0050 (11) | 0.0036 (11) |
C10 | 0.0338 (13) | 0.0366 (14) | 0.0355 (14) | 0.0037 (11) | 0.0059 (11) | 0.0072 (11) |
Geometric parameters (Å, º) top
O1—C7 | 1.238 (2) | C5—C6 | 1.392 (2) |
N1—C7 | 1.331 (2) | C5—H5 | 0.96 |
N1—H1N | 0.90 | C6—C10 | 1.514 (2) |
N1—H2N | 0.90 | C8—H81 | 0.96 |
C1—C2 | 1.396 (2) | C8—H82 | 0.96 |
C1—C6 | 1.403 (2) | C8—H83 | 0.96 |
C1—C7 | 1.498 (2) | C9—H91 | 0.96 |
C2—C3 | 1.393 (2) | C9—H92 | 0.96 |
C2—C8 | 1.511 (2) | C9—H93 | 0.96 |
C3—C4 | 1.389 (2) | C10—H101 | 0.96 |
C3—H3 | 0.96 | C10—H102 | 0.96 |
C4—C5 | 1.389 (2) | C10—H103 | 0.96 |
C4—C9 | 1.507 (2) | | |
| | | |
C7—N1—H1N | 120.0 | O1—C7—N1 | 123.03 (18) |
C7—N1—H2N | 119.3 | O1—C7—C1 | 120.50 (17) |
H1N—N1—H2N | 120.5 | N1—C7—C1 | 116.46 (16) |
C2—C1—C6 | 120.73 (17) | C2—C8—H81 | 110.4 |
C2—C1—C7 | 119.19 (16) | C2—C8—H82 | 110.3 |
C6—C1—C7 | 120.03 (16) | H81—C8—H82 | 111.0 |
C3—C2—C1 | 118.67 (17) | C2—C8—H83 | 110.1 |
C3—C2—C8 | 120.62 (18) | H81—C8—H83 | 105.9 |
C1—C2—C8 | 120.69 (17) | H82—C8—H83 | 109.1 |
C4—C3—C2 | 121.81 (18) | C4—C9—H91 | 112.4 |
C4—C3—H3 | 118.9 | C4—C9—H92 | 111.6 |
C2—C3—H3 | 119.3 | H91—C9—H92 | 106.2 |
C5—C4—C3 | 118.37 (17) | C4—C9—H93 | 113.5 |
C5—C4—C9 | 120.41 (17) | H91—C9—H93 | 107.9 |
C3—C4—C9 | 121.22 (18) | H92—C9—H93 | 104.6 |
C4—C5—C6 | 121.73 (18) | C6—C10—H101 | 110.5 |
C4—C5—H5 | 117.7 | C6—C10—H102 | 109.5 |
C6—C5—H5 | 120.6 | H101—C10—H102 | 110.6 |
C5—C6—C1 | 118.67 (17) | C6—C10—H103 | 109.9 |
C5—C6—C10 | 120.50 (17) | H101—C10—H103 | 110.8 |
C1—C6—C10 | 120.81 (16) | H102—C10—H103 | 105.4 |
| | | |
C2—C1—C7—O1 | 93.9 (2) | C6—C1—C7—O1 | −83.7 (2) |
C2—C1—C7—N1 | −85.7 (2) | C6—C1—C7—N1 | 96.7 (2) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N···O1i | 0.90 | 1.97 | 2.868 (2) | 177 |
N1—H2N···πii | 0.90 | 2.50 | 3.393 (18) | 173 |
Symmetry codes: (i) −x, y−1/2, −z+1/2; (ii) −x, y+1/2, −z+1/2. |
Experimental details
Crystal data |
Chemical formula | C10H13NO |
Mr | 163.21 |
Crystal system, space group | Orthorhombic, Pbca |
Temperature (K) | 130 |
a, b, c (Å) | 14.2587 (9), 8.5369 (6), 14.9245 (10) |
V (Å3) | 1816.7 (2) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.22 × 0.15 × 0.02 |
|
Data collection |
Diffractometer | Kuma KM4CCD κ geometry diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8742, 1597, 1096 |
Rint | 0.049 |
(sin θ/λ)max (Å−1) | 0.595 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.043, 0.090, 1.03 |
No. of reflections | 1597 |
No. of parameters | 122 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.13, −0.18 |
Selected geometric parameters (Å, º) topO1—C7 | 1.238 (2) | C1—C7 | 1.498 (2) |
N1—C7 | 1.331 (2) | | |
| | | |
O1—C7—N1 | 123.03 (18) | N1—C7—C1 | 116.46 (16) |
O1—C7—C1 | 120.50 (17) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N···O1i | 0.90 | 1.97 | 2.868 (2) | 177 |
N1—H2N···πii | 0.90 | 2.50 | 3.393 (18) | 173 |
Symmetry codes: (i) −x, y−1/2, −z+1/2; (ii) −x, y+1/2, −z+1/2. |
Hydrogen-bonding interactions between amide H atoms and carbonyl O atoms give rise to a variety of assembly modes in crystals of primary amides (Leiserowitz & Hagler, 1983; Bernstein et al., 1994). The most common modes are the centrosymmetric cyclic R22(8) hydrogen-bond motif, involving the syn-oriented H atoms, Hs (syn with respect to the adjacent C=O bond), and the C(4) hydrogen-bond motif, engaging the anti-oriented H atoms, Ha. Depending on the symmetry operation relating the centrosymmetric dimers along the C(4) chain, one-dimensional or two-dimensional hydrogen-bonded arrays can be generated in the solid state. For example, in the case of benzamide (Blake & Small, 1972), o-methylbenzamide (Kato et al., 1979) and m-methylbenzamide (Orii et al., 1963), formation of N—Ha···O hydrogen bonds between the translation-related centrosymmetric R22(8) dimers leads to one-dimensional networks. A similar assembly pattern was also observed in crystals of 4-methoxy-2,6-dimethylbenzamide (Mugnoli et al., 1991), whereas neighbouring dimers along the C(4) chain in crystals of p-methylbenzamide are related by a glide plane that generates a two-dimensional array of the hydrogen-bonded molecules (Kato et al., 1981).
Recently, it has been shown that introduction of a bulky triphenylmethyl group at the p-position of the benzamide molecule leads to crystal structures in which the centrosymmetric amide dimers are connected by weak N—Ha···π interactions (Reddy et al., 2002). We report here the crystal structure of 2,4,6-trimethylbenzamide (I), in which a new assembly mode was found for the aromatic primary amide. It is characterized by strong N—Ha···O hydrogen bonds accompanied by weak N—Hs···π interactions (π denotes the aromatic ring centroid). A survey of the Cambridge Structural Database (Version 5.24, 296427 entries; Allen, 2002) gave only three primary benzamide derivatives [HIXNIL (Pandurangi et al., 1998), QELYUB (Zhang et al., 1999) and TUVQIK (Kobayashi et al., 2003)], in which the H···π distance and the N—H···π angle in the N—H···π interactions fall in the ranges 2.0–3.0 Å and 120–180°, respectively.
The structure of (I), with its atom-numbering scheme, is shown in Fig. 1. The carboxamide group and benzene moiety are nearly perpendicular to one another as shown by the dihedral angle of 84.69 (6)°, whereas the corresponding dihedral angles in 4-methoxy-2,6-dimethylbenzamide (Mugnoli et al., 1991) and 2,4,6-trimethylbenzoic acid (Benghiat & Leiserowitz, 1972) were only 56.7 (1) and 48.7°, respectively. The molecules of (I) are connected by N—Ha···O=C interactions that lead to an infinite one-dimensional network characterized by a C(4) hydrogen-bond motif and extending along the [010] direction (Fig. 2 and Table 2). The amide Hs atoms within this chain are involved in N—H···π interactions with the aryl ring of the amide molecules related by the 21 axis (Table 2). Malone et al. (1997) have analyzed X—H···π interactions in small-molecule crystal structures and indicated six possible forms of interaction between an H atom and an aromatic ring. Interactions classified as type I correspond to classical T-shaped geometry and are characterized by the geometric parameters indicated in Fig. 3. The approach geometry of the N—Ha group to the phenyl ring [with the parameters H···π = 2.50 Å, α = 173°, θ = 84° and d = 0.27 Å] allows us to classify the N—H···π interaction in (I) as typical type I.