N-(2,6-Diisopropyl­phen­yl)formamide

Chitanda, J.M.; Quail, J.W.; Foley, S.R.

doi:10.1107/S1600536808024811

organic compounds

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ISSN: 2056-9890

Volume 64| Part 9| September 2008| Page o1728

doi:10.1107/S1600536808024811

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N-(2,6-Diisopropylphenyl)formamide

Jackson M. Chitanda,^a J. Wilson Quail ^b and Stephen R. Foley ^a ^*

^aDepartment of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9, and ^bSaskatchewan Structural Sciences Centre, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
^*Correspondence e-mail: stephen.foley@usask.ca

(Received 9 May 2008; accepted 1 August 2008; online 9 August 2008)

The title compound, C₁₃H₁₉NO, exhibits a non-planar structure in which the 2,6-diisopropylphenyl ring is tilted at a dihedral angle of 77.4 (1)° with respect to the formamide group. This is the largest dihedral angle known among structurally characterized formamides. The molecules are linked via N—H⋯O hydrogen bonds, forming infinite chains which run along the b-axis directions.

Related literature

For related literature, see: Boeyens et al. (1988 ); Ferguson et al. (1998 ); Gowda et al. (2000 ); Krishnamurthy (1982 ); LaPlanche & Rogers (1964 ); Omondi et al. (2005 ); Cerecetto et al. (2004 ); Chitanda et al. (2008 ).

Experimental

Crystal data

C₁₃H₁₉NO
M_r = 205.29
Monoclinic, P 2₁ /c
a = 8.9581 (15) Å
b = 8.7684 (15) Å
c = 15.840 (6) Å
β = 105.381 (10)°
V = 1199.6 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 173 (2) K
0.25 × 0.05 × 0.05 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: none
7758 measured reflections
2365 independent reflections
1556 reflections with I > 2σ(I)
R_int = 0.070

Refinement

R[F² > 2σ(F²)] = 0.054
wR(F²) = 0.128
S = 1.05
2365 reflections
140 parameters
H-atom parameters constrained
Δρ_max = 0.15 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O1ⁱ	0.88	2.04	2.910 (2)	171
Symmetry code: (i) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: COLLECT (Nonius, 1998 ); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ); data reduction: DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808024811/bv2100sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808024811/bv2100Isup2.hkl

checkCIF report

Comment top

As part of the ongoing research in our laboratory directed at the synthesis substituted iminoisoindolines (Chitanda et al., 2008), the title compound was obtained as a by-product and then purposefully synthesized in 92% yield. N-(2,6-diisopropylphenyl)formamide has been previously reported (Krishnamurthy, 1982), however no X-ray structure nor NMR data has been previously published. We have now determined the single-crystal X-ray structure of the title compound, (I).

The ¹H NMR (CDCl₃) spectra of I is a mixture of two carbon-nitrogen bond rotomers, where the ratio of the major rotomer to the minor rotomer is about 2:1. Upon crystallization however, the solid state structure shows exclusive formation of the cisoidal rotomer. As shown in Figure 1, the carbonyl group on the formamide moiety is positioned almost perpendicular to the plane of the aromatic ring, and is oriented cis to the aromatic group about the carbon-nitrogen bond. The dihedral angle between the plane of the aromatic ring and that formed by the N—C=O moiety is 77.4 (1)°, which is considerably larger than the corresponding angle in previously structurally characterized aryl-substituted formamides (Figure 3). This is attributed to the presence of the bulky isopropyl groups on the ortho positions of the phenyl ring which increases torsional strain between the two planes defining the dihedral angle. For example, in the less bulky analogue, N-(4-methoxyphenyl)formamide, the dihedral angle is only 8.0 (3)° (Figure 3, Cerecetto et al., 2004). The two isomers of the title compound arise due to hindered rotation about the amidic bond (LaPlanche et al., 1964). (I) crystallizes in the monoclinic space group P21/c. The molecules of (I) are linked to form infinite chains which run along the b axis direction via N—H···O hydrogen bonds (details in Table 3).

Related literature top

For related literature, see: Boeyens et al. (1988); Ferguson et al. (1998); Gowda et al. (2000); Krishnamurthy (1982); LaPlanche & Rogers (1964); Omondi et al. (2005); Cerecetto et al. (2004); Chitanda et al. (2008).

Experimental top

The refined procedure for the synthesis of (I) is as follows: A solution of 2,6-diisopropyl aniline (4.695 g, 26.5 mmol s) and formic acid (7.314 g, 159.0 mmol, 6eq.) in chloroform (20 ml) was refluxed with continuous stirring for 16 hrs. The colour of the solution changed from yellow to green to colorless over the course of the reaction. The solvent and excess formic acid were removed under vacuum to yield the title compound as a white solid. Needle-like single crystals suitable for X-ray analysis were obtained from slow evaporation of a chloroform solution (5.00 g, 92%). 1H-NMR (CDCl₃, p.p.m.): Two rotomers observed in 2:1 ratio. Major Rotomer: δ 1.19 (d, J = 6.9 Hz, 12H, –CH(CH3)2), δ 3.08 (septet, J = 6.9 Hz, 2H, –CH(CH₃)₂) δ 6.64 (s(br), 1H, –NH–), δ 7.17 (m, 2H, aromatic), δ 7.30 (m, 1H, aromatic), δ 8.47 (s, 1H, –C(H)=O). ¹³C-NMR (CDCl₃, p.p.m.): δ 23.74 (CH(CH3)2), d 28.9 (–CH(CH3)2), d 123.6, δ 128.7, δ 129.9, δ 146.2, δ 161.0 (–C(H)=O). Minor Rotomer: δ 1.20 (d, J = 6.9 Hz, 12H, –CH(CH₃)₂), δ 3.20 (septet, J = 6.9 Hz, 2H, –CH(CH₃)₂) δ 7.02 (d, J = 11.2 Hz, 1H, –NH–), δ 7.19 (m, 2H, aromatic), δ 7.30 (m, 1H, aromatic), δ 8.0 (d, J = 11.2 Hz, 1H, –C(H)=O). ¹³C-NMR (CDCl₃, p.p.m.), Major Rotomer: δ 23.77 (–CH(CH₃)₂), δ 28.6 (–CH(CH₃)₂), δ 123.9, δ 129.0, δ 130.4, δ 146.9, δ 165.9 (–C(H)=O). ESI-MS (m/z): calcd. for C13H19NO; 205.1467, 206.1545 [M+H]⁺; found; 206.1546 [M+H]⁺.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. The molecular structure of (I), showing the atom-labeling scheme. Thermal ellipsoids are drawn at the 50% probability level.
	Fig. 2. The packing of (I), with hydrogen bonds shown as dashed lines. For clarity, H-atoms have been omitted.
	Fig. 3. Dihedral angle of previously characterized aryl-substituted formamides

N-(2,6-Diisopropylphenyl)formamide top

Crystal data top

C₁₃H₁₉NO	F(000) = 448
M_r = 205.29	D_x = 1.137 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 5165 reflections
a = 8.9581 (15) Å	θ = 1.0–27.5°
b = 8.7684 (15) Å	µ = 0.07 mm⁻¹
c = 15.840 (6) Å	T = 173 K
β = 105.381 (10)°	Rod, colourless
V = 1199.6 (5) Å³	0.25 × 0.05 × 0.05 mm
Z = 4

Data collection top

Nonius KappaCCD diffractometer	1556 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.070
Horizonally mounted graphite crystal monochromator	θ_max = 26.0°, θ_min = 2.4°
Detector resolution: 9 pixels mm^-1	h = −11→11
ϕ scans and ω scans with κ offsets	k = −10→10
7758 measured reflections	l = −17→19
2365 independent reflections

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)] = 0.054	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.128	H-atom parameters constrained
S = 1.05	w = 1/[σ²(F_o²) + (0.0512P)² + 0.2338P] where P = (F_o² + 2F_c²)/3
2365 reflections	(Δ/σ)_max < 0.001
140 parameters	Δρ_max = 0.16 e Å⁻³
0 restraints	Δρ_min = −0.20 e Å⁻³

Crystal data top

C₁₃H₁₉NO	V = 1199.6 (5) Å³
M_r = 205.29	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 8.9581 (15) Å	µ = 0.07 mm⁻¹
b = 8.7684 (15) Å	T = 173 K
c = 15.840 (6) Å	0.25 × 0.05 × 0.05 mm
β = 105.381 (10)°

Data collection top

Nonius KappaCCD diffractometer	1556 reflections with I > 2σ(I)
7758 measured reflections	R_int = 0.070
2365 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.054	0 restraints
wR(F²) = 0.128	H-atom parameters constrained
S = 1.05	Δρ_max = 0.16 e Å⁻³
2365 reflections	Δρ_min = −0.20 e Å⁻³
140 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.

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 (Å²) top

	x	y	z	U_iso*/U_eq
N1	0.51988 (18)	0.05926 (16)	0.22728 (10)	0.0277 (4)
H1	0.5445	−0.0380	0.2282	0.033*
O1	0.40304 (16)	0.24069 (14)	0.29095 (9)	0.0385 (4)
C1	0.5662 (2)	0.15772 (18)	0.16592 (12)	0.0253 (4)
C2	0.7219 (2)	0.20161 (19)	0.18370 (13)	0.0276 (5)
C3	0.7655 (2)	0.2939 (2)	0.12239 (14)	0.0311 (5)
H3	0.8701	0.3260	0.1329	0.037*
C4	0.6582 (2)	0.3389 (2)	0.04654 (14)	0.0326 (5)
H4	0.6898	0.4012	0.0053	0.039*
C5	0.5059 (2)	0.2940 (2)	0.03028 (13)	0.0319 (5)
H5	0.4337	0.3255	−0.0223	0.038*
C6	0.4557 (2)	0.20300 (19)	0.08966 (12)	0.0267 (4)
C7	0.2869 (2)	0.1551 (2)	0.06884 (13)	0.0327 (5)
H7	0.2744	0.0866	0.1170	0.039*
C8	0.2398 (3)	0.0654 (3)	−0.01662 (16)	0.0514 (7)
H8A	0.1320	0.0322	−0.0273	0.062*
H8B	0.3069	−0.0241	−0.0125	0.062*
H8C	0.2504	0.1304	−0.0650	0.062*
C9	0.1804 (2)	0.2920 (2)	0.06525 (17)	0.0460 (6)
H9A	0.0736	0.2566	0.0564	0.055*
H9B	0.1867	0.3587	0.0167	0.055*
H9C	0.2125	0.3487	0.1204	0.055*
C10	0.8387 (2)	0.1508 (2)	0.26749 (14)	0.0349 (5)
H10	0.8116	0.0441	0.2800	0.042*
C11	1.0061 (2)	0.1496 (3)	0.26122 (17)	0.0505 (6)
H11A	1.0727	0.1026	0.3140	0.061*
H11B	1.0404	0.2545	0.2560	0.061*
H11C	1.0125	0.0909	0.2097	0.061*
C12	0.8260 (3)	0.2501 (3)	0.34482 (15)	0.0468 (6)
H12A	0.8939	0.2092	0.3991	0.056*
H12B	0.7187	0.2499	0.3488	0.056*
H12C	0.8573	0.3548	0.3360	0.056*
C13	0.4417 (2)	0.1082 (2)	0.28273 (13)	0.0309 (5)
H13	0.4131	0.0339	0.3192	0.037*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0361 (9)	0.0177 (7)	0.0303 (10)	−0.0005 (6)	0.0103 (8)	0.0028 (6)
O1	0.0492 (9)	0.0278 (7)	0.0443 (9)	−0.0025 (6)	0.0228 (7)	−0.0035 (6)
C1	0.0337 (11)	0.0167 (8)	0.0276 (11)	−0.0004 (7)	0.0120 (9)	0.0001 (7)
C2	0.0339 (11)	0.0187 (9)	0.0328 (12)	0.0019 (8)	0.0134 (9)	−0.0012 (7)
C3	0.0331 (11)	0.0229 (9)	0.0415 (13)	−0.0020 (8)	0.0171 (10)	−0.0035 (8)
C4	0.0464 (13)	0.0236 (9)	0.0354 (12)	0.0022 (9)	0.0240 (10)	0.0038 (8)
C5	0.0410 (12)	0.0272 (10)	0.0284 (11)	0.0044 (8)	0.0109 (9)	0.0027 (8)
C6	0.0348 (11)	0.0205 (9)	0.0270 (11)	0.0014 (8)	0.0120 (9)	−0.0018 (7)
C7	0.0339 (12)	0.0314 (10)	0.0312 (12)	−0.0015 (8)	0.0058 (9)	0.0026 (8)
C8	0.0455 (14)	0.0435 (13)	0.0606 (17)	−0.0008 (10)	0.0062 (12)	−0.0204 (11)
C9	0.0364 (13)	0.0465 (13)	0.0544 (16)	0.0002 (10)	0.0106 (11)	−0.0147 (11)
C10	0.0342 (12)	0.0284 (10)	0.0394 (13)	0.0004 (8)	0.0050 (10)	0.0049 (9)
C11	0.0374 (13)	0.0464 (13)	0.0636 (17)	0.0068 (10)	0.0065 (12)	0.0032 (11)
C12	0.0397 (13)	0.0600 (14)	0.0379 (14)	−0.0037 (11)	0.0052 (11)	−0.0007 (11)
C13	0.0361 (11)	0.0271 (10)	0.0305 (11)	−0.0062 (8)	0.0106 (9)	0.0022 (8)

Geometric parameters (Å, º) top

N1—C13	1.331 (2)	C7—H7	1.0000
N1—C1	1.441 (2)	C8—H8A	0.9800
N1—H1	0.8800	C8—H8B	0.9800
O1—C13	1.229 (2)	C8—H8C	0.9800
C1—C6	1.401 (3)	C9—H9A	0.9800
C1—C2	1.402 (3)	C9—H9B	0.9800
C2—C3	1.397 (3)	C9—H9C	0.9800
C2—C10	1.522 (3)	C10—C11	1.529 (3)
C3—C4	1.382 (3)	C10—C12	1.532 (3)
C3—H3	0.9500	C10—H10	1.0000
C4—C5	1.377 (3)	C11—H11A	0.9800
C4—H4	0.9500	C11—H11B	0.9800
C5—C6	1.396 (3)	C11—H11C	0.9800
C5—H5	0.9500	C12—H12A	0.9800
C6—C7	1.520 (3)	C12—H12B	0.9800
C7—C9	1.525 (3)	C12—H12C	0.9800
C7—C8	1.525 (3)	C13—H13	0.9500

C13—N1—C1	123.23 (15)	C7—C8—H8C	109.5
C13—N1—H1	118.4	H8A—C8—H8C	109.5
C1—N1—H1	118.4	H8B—C8—H8C	109.5
C6—C1—C2	122.22 (17)	C7—C9—H9A	109.5
C6—C1—N1	119.19 (16)	C7—C9—H9B	109.5
C2—C1—N1	118.57 (17)	H9A—C9—H9B	109.5
C3—C2—C1	117.78 (18)	C7—C9—H9C	109.5
C3—C2—C10	121.42 (17)	H9A—C9—H9C	109.5
C1—C2—C10	120.80 (16)	H9B—C9—H9C	109.5
C4—C3—C2	120.77 (18)	C2—C10—C11	113.87 (18)
C4—C3—H3	119.6	C2—C10—C12	110.56 (16)
C2—C3—H3	119.6	C11—C10—C12	109.77 (18)
C5—C4—C3	120.46 (18)	C2—C10—H10	107.5
C5—C4—H4	119.8	C11—C10—H10	107.5
C3—C4—H4	119.8	C12—C10—H10	107.5
C4—C5—C6	121.17 (19)	C10—C11—H11A	109.5
C4—C5—H5	119.4	C10—C11—H11B	109.5
C6—C5—H5	119.4	H11A—C11—H11B	109.5
C5—C6—C1	117.59 (18)	C10—C11—H11C	109.5
C5—C6—C7	119.45 (17)	H11A—C11—H11C	109.5
C1—C6—C7	122.95 (16)	H11B—C11—H11C	109.5
C6—C7—C9	111.57 (15)	C10—C12—H12A	109.5
C6—C7—C8	111.09 (17)	C10—C12—H12B	109.5
C9—C7—C8	110.50 (18)	H12A—C12—H12B	109.5
C6—C7—H7	107.8	C10—C12—H12C	109.5
C9—C7—H7	107.8	H12A—C12—H12C	109.5
C8—C7—H7	107.8	H12B—C12—H12C	109.5
C7—C8—H8A	109.5	O1—C13—N1	125.92 (17)
C7—C8—H8B	109.5	O1—C13—H13	117.0
H8A—C8—H8B	109.5	N1—C13—H13	117.0

C13—N1—C1—C6	−77.0 (2)	N1—C1—C6—C5	−177.80 (15)
C13—N1—C1—C2	104.7 (2)	C2—C1—C6—C7	179.32 (16)
C6—C1—C2—C3	0.1 (3)	N1—C1—C6—C7	1.1 (3)
N1—C1—C2—C3	178.38 (15)	C5—C6—C7—C9	−64.7 (2)
C6—C1—C2—C10	179.73 (16)	C1—C6—C7—C9	116.4 (2)
N1—C1—C2—C10	−2.0 (2)	C5—C6—C7—C8	59.1 (2)
C1—C2—C3—C4	−0.5 (3)	C1—C6—C7—C8	−119.8 (2)
C10—C2—C3—C4	179.90 (17)	C3—C2—C10—C11	−24.2 (3)
C2—C3—C4—C5	0.3 (3)	C1—C2—C10—C11	156.20 (17)
C3—C4—C5—C6	0.3 (3)	C3—C2—C10—C12	99.9 (2)
C4—C5—C6—C1	−0.7 (3)	C1—C2—C10—C12	−79.7 (2)
C4—C5—C6—C7	−179.57 (17)	C1—N1—C13—O1	−2.2 (3)
C2—C1—C6—C5	0.4 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱ	0.88	2.04	2.910 (2)	171

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

Experimental details

Crystal data
Chemical formula	C₁₃H₁₉NO
M_r	205.29
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	173
a, b, c (Å)	8.9581 (15), 8.7684 (15), 15.840 (6)
β (°)	105.381 (10)
V (Å³)	1199.6 (5)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.07
Crystal size (mm)	0.25 × 0.05 × 0.05

Data collection
Diffractometer	Nonius KappaCCD diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	7758, 2365, 1556
R_int	0.070
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.054, 0.128, 1.05
No. of reflections	2365
No. of parameters	140
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.16, −0.20

Computer programs: COLLECT (Nonius, 1998), DENZO and SCALEPACK (Otwinowski & Minor, 1997), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱ	0.88	2.04	2.910 (2)	170.8

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

Acknowledgements

Financial assistance for this project was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC) for an operating grant to SRF, and by the Canadian Government through the Commonwealth Scholarship fund for JMC.

References

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