2,4,6-Tri­methyl­acetanilide

The title compound, C₁₁H₁₅NO, also known as N-(2,4,6-tri­methyl­phenyl)­acet­amide, is an organic non-linear optical material. It crystallizes in the monoclinic system, in a non-centrosymmetric space group Pn.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.045
• wR factor = 0.116
• Data-to-parameter ratio = 17.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



STRVAL_01
         From the CIF: _refine_ls_abs_structure_Flack   -0.900
         From the CIF: _refine_ls_abs_structure_Flack_su    1.700
           Alert C Flack parameter is too small

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           28.01
         From the CIF: _reflns_number_total               2182
         Count of symmetry unique reflns         1291
         Completeness (_total/calc)            169.02%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured       891
         Fraction of Friedel pairs measured     0.690
         Are heavy atom types Z>Si present           no
          ALERT: MoKa measured Friedel data cannot be used to
                 determine absolute structure in a light-atom
                 study EXCEPT under VERY special conditions.
                 It is preferred that Friedel data is merged in such cases.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

---

S1. Comment

The title compound, (I), is found to be of interest as an organic non-linear optical material. The crystals show optical second harmonic generation with the fundamental beam (λ = 1064 nm) of Nd–YAG laser. The single-crystal structure elucidation in a non-centrosymmetric space group further reinforces this observation.

Fig. 1 shows the title molecule. The torsion angle about the C1—N1 bond is 71.4 (3)°, which shows that the amide group is almost perpendicular to the plane of the phenyl ring (Table 1). The packing shows intermolecular (N—H···O) hydrogen bonds running along [101] (Fig. 2 and Table 2).

S2. Experimental

The title compound, (I), was prepared by the direct reaction of 2,4,6-trimethylaniline and acetic anhydride at room tempertaure for 10 min. Crystals of (I) suitable for single-crystal diffraction study were grown at ambient temperature by slow evaporation of a methanol solution. The compound crystallizes as colorless prisms.

S3. Refinement

The absolute structure could not be determined by the Flack (1983) test.

Computing details

Data collection: SMART (Bruker 1998); cell refinement: SMART (Bruker 1998); data reduction: SAINT (Bruker 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and CAMERON (Watkin et al., 1996); software used to prepare material for publication: PLATON (Spek, 1990).

Figures

	Fig. 1. View of the molecule of (I) with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. Packing diagram of (I), viewed down the b axis.

N-[2,4,6-trimethylphenyl]acetamide

Crystal data

C11H15NO	F(000) = 192
Mr = 177.24	Dx = 1.106 Mg m^−3
Monoclinic, Pn	Melting point: 492 K
Hall symbol: P -2yac	Mo Kα radiation, λ = 0.71073 Å
a = 8.200 (4) Å	Cell parameters from 775 reflections
b = 8.538 (4) Å	θ = 3.6–26.2°
c = 8.295 (4) Å	µ = 0.07 mm^−1
β = 113.626 (6)°	T = 293 K
V = 532.1 (4) Å^3	Prism, colorless
Z = 2	0.52 × 0.44 × 0.21 mm

Data collection

Bruker SMART CCD area-detector diffractometer	1932 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.021
Graphite monochromator	θmax = 28.0°, θmin = 2.4°
ϕ and ω scans	h = −9→10
4076 measured reflections	k = −10→11
2182 independent reflections	l = −10→10

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.045	H-atom parameters constrained
wR(F^2) = 0.116	w = 1/[σ^2(Fo^2) + (0.066P)^2 + 0.0215P] where P = (Fo^2 + 2Fc^2)/3
S = 1.13	(Δ/σ)max = 0.010
2182 reflections	Δρmax = 0.17 e Å^−3
122 parameters	Δρmin = −0.15 e Å^−3
2 restraints	Absolute structure: Flack (1983), 891 Friedel pairs
0 constraints	Absolute structure parameter: −0.9 (17)
Primary atom site location: structure-invariant direct methods

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All e.s.d.'s are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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	0.1327 (2)	0.38285 (16)	0.54089 (19)	0.0631 (4)
N1	0.3689 (2)	0.53910 (16)	0.69428 (18)	0.0446 (4)
C1	0.3345 (2)	0.66024 (19)	0.5633 (2)	0.0403 (5)
C2	0.3574 (3)	0.6313 (2)	0.4070 (2)	0.0482 (5)
C3	0.3264 (3)	0.7532 (2)	0.2860 (3)	0.0512 (6)
C4	0.2747 (2)	0.9031 (2)	0.3171 (2)	0.0485 (6)
C5	0.2531 (2)	0.9278 (2)	0.4732 (3)	0.0474 (6)
C6	0.2818 (2)	0.8088 (2)	0.5982 (2)	0.0422 (5)
C7	0.4160 (4)	0.4708 (3)	0.3697 (3)	0.0732 (9)
C8	0.2465 (3)	1.0344 (3)	0.1842 (3)	0.0691 (8)
C9	0.2569 (3)	0.8398 (3)	0.7665 (3)	0.0594 (7)
C10	0.2654 (2)	0.41175 (19)	0.6758 (2)	0.0446 (5)
C11	0.3229 (3)	0.3045 (2)	0.8345 (3)	0.0608 (6)
H1	0.46188	0.54873	0.79081	0.0536*
H3	0.34038	0.73458	0.18178	0.0615*
H5	0.21853	1.02638	0.49532	0.0569*
H7A	0.31822	0.39879	0.33828	0.1099*
H7B	0.51304	0.43345	0.47297	0.1099*
H7C	0.45383	0.47900	0.27447	0.1099*
H8A	0.35781	1.05982	0.17798	0.1037*
H8B	0.20075	1.12524	0.22038	0.1037*
H8C	0.16301	1.00096	0.07058	0.1037*
H9A	0.20392	0.94113	0.76021	0.0892*
H9B	0.37040	0.83689	0.86451	0.0892*
H9C	0.18054	0.76109	0.78147	0.0892*
H11A	0.21983	0.26865	0.85134	0.0912*
H11B	0.39970	0.36065	0.93712	0.0912*
H11C	0.38552	0.21614	0.81563	0.0912*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0576 (8)	0.0547 (8)	0.0502 (7)	−0.0125 (7)	−0.0064 (6)	0.0068 (6)
N1	0.0454 (8)	0.0388 (8)	0.0367 (7)	−0.0024 (6)	0.0028 (6)	0.0016 (6)
C1	0.0370 (8)	0.0382 (9)	0.0394 (8)	−0.0029 (7)	0.0087 (7)	−0.0011 (7)
C2	0.0504 (10)	0.0423 (9)	0.0462 (9)	0.0014 (8)	0.0134 (8)	−0.0046 (7)
C3	0.0555 (11)	0.0564 (11)	0.0412 (8)	−0.0023 (9)	0.0188 (8)	−0.0028 (8)
C4	0.0444 (10)	0.0469 (10)	0.0465 (9)	−0.0036 (8)	0.0103 (8)	0.0053 (8)
C5	0.0426 (10)	0.0378 (9)	0.0582 (10)	−0.0006 (7)	0.0164 (9)	0.0002 (8)
C6	0.0386 (9)	0.0384 (9)	0.0458 (9)	−0.0055 (7)	0.0129 (8)	−0.0045 (7)
C7	0.103 (2)	0.0545 (12)	0.0714 (14)	0.0153 (12)	0.0448 (14)	−0.0060 (11)
C8	0.0726 (15)	0.0601 (14)	0.0684 (13)	0.0018 (11)	0.0216 (12)	0.0202 (11)
C9	0.0722 (14)	0.0527 (10)	0.0596 (12)	0.0006 (10)	0.0329 (11)	−0.0055 (9)
C10	0.0417 (9)	0.0389 (9)	0.0420 (9)	0.0027 (7)	0.0050 (8)	0.0013 (7)
C11	0.0587 (12)	0.0511 (10)	0.0524 (11)	−0.0018 (9)	0.0011 (9)	0.0142 (9)

Geometric parameters (Å, º)

O1—C10	1.233 (2)	C3—H3	0.9302
N1—C1	1.444 (2)	C5—H5	0.9296
N1—C10	1.350 (2)	C7—H7A	0.9599
N1—H1	0.8602	C7—H7B	0.9604
C1—C6	1.407 (2)	C7—H7C	0.9600
C1—C2	1.404 (3)	C8—H8A	0.9595
C2—C3	1.397 (3)	C8—H8B	0.9605
C2—C7	1.524 (3)	C8—H8C	0.9598
C3—C4	1.404 (3)	C9—H9A	0.9601
C4—C5	1.392 (3)	C9—H9B	0.9598
C4—C8	1.524 (3)	C9—H9C	0.9599
C5—C6	1.403 (3)	C11—H11A	0.9603
C6—C9	1.513 (3)	C11—H11B	0.9599
C10—C11	1.515 (3)	C11—H11C	0.9601
O1···C2	3.282 (3)	H1···H11B	2.1926
O1···C7	3.259 (4)	H1···O1^ii	2.0682
O1···N1^i	2.899 (2)	H3···H7C	2.3759
O1···H7A	2.6845	H5···H8B	2.3809
O1···H1^i	2.0682	H5···H9A	2.3629
O1···H9B^i	2.7865	H7A···O1	2.6845
O1···H11B^i	2.8052	H7A···C10	3.0017
N1···O1^ii	2.899 (2)	H7A···H8B^iv	2.5660
N1···H9B	2.9060	H7B···N1	2.7055
N1···H9C	2.7196	H7C···H3	2.3759
N1···H7B	2.7055	H8B···H5	2.3809
C2···O1	3.282 (3)	H8B···H7A^v	2.5660
C7···C10	3.277 (4)	H9A···H5	2.3629
C7···O1	3.259 (4)	H9B···N1	2.9060
C10···C7	3.277 (4)	H9B···O1^ii	2.7865
C3···H11A^iii	3.0553	H9C···N1	2.7196
C5···H11C^i	3.0243	H11A···C3^vi	3.0553
C9···H1	2.9615	H11B···H1	2.1926
C10···H7A	3.0017	H11B···O1^ii	2.8052
H1···C9	2.9615	H11C···C5^ii	3.0243
C1—N1—C10	124.57 (14)	C2—C7—H7A	109.51
C10—N1—H1	117.72	C2—C7—H7B	109.47
C1—N1—H1	117.71	C2—C7—H7C	109.49
N1—C1—C6	118.33 (14)	H7A—C7—H7B	109.44
N1—C1—C2	120.71 (15)	H7A—C7—H7C	109.48
C2—C1—C6	120.95 (15)	H7B—C7—H7C	109.43
C3—C2—C7	120.36 (18)	C4—C8—H8A	109.48
C1—C2—C7	121.01 (16)	C4—C8—H8B	109.46
C1—C2—C3	118.63 (17)	C4—C8—H8C	109.47
C2—C3—C4	121.9 (2)	H8A—C8—H8B	109.46
C5—C4—C8	121.52 (17)	H8A—C8—H8C	109.51
C3—C4—C5	118.00 (16)	H8B—C8—H8C	109.44
C3—C4—C8	120.47 (17)	C6—C9—H9A	109.45
C4—C5—C6	122.13 (16)	C6—C9—H9B	109.48
C1—C6—C9	120.91 (16)	C6—C9—H9C	109.46
C5—C6—C9	120.71 (17)	H9A—C9—H9B	109.47
C1—C6—C5	118.38 (15)	H9A—C9—H9C	109.48
N1—C10—C11	115.19 (15)	H9B—C9—H9C	109.49
O1—C10—N1	123.38 (15)	C10—C11—H11A	109.48
O1—C10—C11	121.44 (16)	C10—C11—H11B	109.50
C2—C3—H3	119.07	C10—C11—H11C	109.50
C4—C3—H3	119.03	H11A—C11—H11B	109.46
C4—C5—H5	118.91	H11A—C11—H11C	109.43
C6—C5—H5	118.95	H11B—C11—H11C	109.47
C10—N1—C1—C2	−71.4 (3)	N1—C1—C6—C5	178.27 (16)
C10—N1—C1—C6	110.12 (19)	C6—C1—C2—C3	−0.1 (3)
C1—N1—C10—O1	2.7 (3)	C7—C2—C3—C4	−179.1 (2)
C1—N1—C10—C11	−177.07 (17)	C1—C2—C3—C4	0.5 (3)
N1—C1—C6—C9	−1.6 (3)	C2—C3—C4—C5	−0.6 (3)
C2—C1—C6—C5	−0.2 (3)	C2—C3—C4—C8	178.5 (2)
N1—C1—C2—C3	−178.55 (19)	C8—C4—C5—C6	−178.80 (19)
N1—C1—C2—C7	1.1 (3)	C3—C4—C5—C6	0.2 (3)
C2—C1—C6—C9	179.91 (18)	C4—C5—C6—C1	0.1 (3)
C6—C1—C2—C7	179.5 (2)	C4—C5—C6—C9	−179.95 (18)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1^ii	0.86	2.07	2.899 (2)	162

Symmetry code: (ii) x+1/2, −y+1, z+1/2.