Monoclinic form of 2-{5,5-di­methyl-3-[2-(2,4,6-tri­methoxy­phenyl)­vinyl]cyclo­hex-2-enyl­idene}malono­nitrile

On slow evaporation of an ethyl acetate solution, the title compound, C₂₂H₂₄N₂O₃, crystallizes simultaneously in two crystalline forms, differing in colour, size and shape. The mol­ecule in the violet plate-like monoclinic crystal reported here is almost planar with the exception of the di­methyl­cyclo­hexene moiety, which has a twisted conformation. The red triclinic crystals [see Kolev et al. (2001a), Acta Cryst. E57, o966-o967] are built of the same mol­ecules with similar geometry; however, the cyclo­hexene fragment in the triclinic crystal has a more symmetric sofa conformation. Another difference between the structures is the existence of a non-classical hydrogen bond involving one of the nitrile groups in the triclinic form. The mol­ecules in the monoclinic form are held together by van der Waals interactions.

Key indicators

• Single-crystal X-ray study
• T = 291 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.054
• wR factor = 0.136
• Data-to-parameter ratio = 14.7

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



ABSMU_01  Alert C The ratio of given/expected absorption coefficient lies
          outside the range 0.99 <> 1.01
          Calculated value of mu =     0.081
          Value of mu given      =     0.080

PLAT_371  Alert C Long   C(sp2)-C(sp1) Bond  C(7)   -   C(8)   =       1.42 Ang.

PLAT_371  Alert C Long   C(sp2)-C(sp1) Bond  C(7)   -   C(9)   =       1.43 Ang.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 3 Alert Level C = Please check

---

S1. Comment

Due to their solvatochromic behaviour (Lemke, 1970), the derivatives of 2-(5,5-dimethyl-3-styrylcyclohex-2-enylidene)malononitrile are supposed to be good candidates for nonlinear optical (NLO) and electrooptical applications. In the course of our investigations on this class of substances, we studied the crystal structures of the title compound, (I).

The mean molecular plane orientations in the monoclinic crystal of the title compound alternate between (113) and (113). The least-squares plane through atoms C1/C2/C3/C4/C6 in the cyclohexene ring indicates a better planarity for the plane in the triclinic crystal (Kolev et al., 2001a) [χ² = 44, maximum deviation from planarity = 0.0090 (19) Å] than in the monoclinic crystal [χ² = 676, maximum deviation from planarity = 0.035 (3) Å]. The dihedral angle between this plane and the least-squares plane of the C14—C19 phenyl ring is 4.69 (5)° in the triclinic and 8.87 (8)° in the monoclinic crystal, which means that the deviations from the overall planarity of the molecule are also smaller in the triclinic crystal. The six torsion angles in the cyclohexene ring [triclinic: -0.8 (3), 1.7 (3), -28.6 (3), 51.7 (2), 27.2 (3) and -51.4 (2)°; monoclinic: -3.0 (4), -2.7 (4), 32.0 (3), -52.8 (3), -21.2 (3) and 47.8 (3)°; both sequences correspond to endocyclic torsion angles associated with the bonds C1—C2 through C6—C1 in the cycle] indicate a higher symmetry of the conformation of the cyclohexene ring in the triclinic crystal.

In the triclinic crystal, the intermolecular contact of 2.60 Å between the H10C and N2(x + 1, y, z) atoms indicates a non-classical hydrogen bond [with the C10—H10C ··· N2(x + 1, y, z) angle equal to 160°], whereas the molecules in the monoclinic crystal are held together by pure van der Waals interactions.

S2. Experimental

The title compound was synthesized using a general procedure described by Lemke (1970). The preparation of the starting compound, 3,5,5-trimethyl(cyclohex-2-enylidene)malonodinitrile, C₁₂H₁₄N₂, is described in one of our previous papers (Kolev et al., 2001b). The starting compound (5 mmol) was dissolved in 60 ml of dry toluene by continuous stirring. 2,4,6-Trimethoxy-benzaldehyde (5 mmol) was added to the solution, and nearly 1 ml of triethylamine was used as a catalyst. The solution became red after a few minutes and the resulting compound precipitated. After 6 h reaction time, the solution was cooled and 2-{5,5-dimethyl-3-[2-(2,4,6-trimethoxyphenyl)vinyl]cyclohex-2-enylidene}- malononitrile was isolated and recrystallized twice from ethyl acetate with an excellent yield of 92% (m.p. 477–478 K). The purity of the compound was confirmed by elemental analysis, IR, UV-vis and mass spectrometry. Two types of crystals, different in colour, size and shape, were grown simultaneously from an ethyl acetate solution by slow evaporation over a period of several days. They were separated manually.

S3. Refinement

H atoms were placed in calculated positions with U_iso constrained to be 1.5U_eq of the carrier atom for the methyl-H and 1.2U_eq for the remaining H atoms.

Computing details

Data collection: COLLECT (Nonius, 1998); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-Plus (Sheldrick, 1991); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997), PARST95 (Nardelli, 1995) and PLATON (Spek, 2001).

Figures

Fig. 1. View of the title compound showing the labelling of non-H atoms. Displacement ellipsoids are shown at 50% probability level. H atoms are drawn as circles of arbitrary radii.

(I)

Crystal data

C22H24N2O3	F(000) = 776
Mr = 364.43	Dx = 1.209 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 10.7130 (3) Å	Cell parameters from 30702 reflections
b = 9.0471 (3) Å	θ = 3.1–25.4°
c = 20.6565 (7) Å	µ = 0.08 mm^−1
β = 90.1565 (13)°	T = 291 K
V = 2002.05 (11) Å^3	Plate, violet
Z = 4	0.5 × 0.3 × 0.15 mm

Data collection

Nonius KappaCCD diffractometer	1654 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.063
Graphite monochromator	θmax = 25.4°, θmin = 3.1°
Detector resolution: 19 vertical, 18 horizontal pixels mm^-1	h = −12→12
277 frames via ω–rotation (Δω = 1°) and two times 5 s per frame with 3 sets at different κ–angles scans	k = −10→10
30702 measured reflections	l = −24→24
3595 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)] = 0.054	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.136	H-atom parameters constrained
S = 0.95	w = 1/[σ^2(Fo^2) + (0.0589P)^2] where P = (Fo^2 + 2Fc^2)/3
3595 reflections	(Δ/σ)max < 0.001
244 parameters	Δρmax = 0.15 e Å^−3
0 restraints	Δρmin = −0.16 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	0.10139 (17)	0.90442 (19)	0.11949 (8)	0.0608 (5)
O2	0.42499 (17)	1.2395 (2)	0.16927 (8)	0.0702 (6)
O3	0.34379 (18)	1.0912 (2)	−0.05091 (8)	0.0667 (6)
N1	−0.3470 (2)	0.3285 (3)	−0.19234 (12)	0.0763 (8)
N2	−0.3435 (2)	0.4407 (3)	0.01276 (12)	0.0730 (8)
C1	0.0244 (2)	0.7186 (3)	−0.06374 (11)	0.0439 (7)
C2	−0.0796 (2)	0.6328 (3)	−0.05675 (12)	0.0484 (7)
H2A	−0.1173	0.6287	−0.0163	0.058*
C3	−0.1332 (2)	0.5494 (3)	−0.10815 (11)	0.0443 (7)
C4	−0.0761 (2)	0.5612 (3)	−0.17384 (11)	0.0516 (7)
H4A	−0.1154	0.6420	−0.1971	0.062*
H4B	−0.0926	0.4709	−0.1977	0.062*
C5	0.0648 (3)	0.5875 (3)	−0.17162 (11)	0.0488 (7)
C6	0.0906 (2)	0.7210 (3)	−0.12797 (11)	0.0531 (7)
H6A	0.1798	0.7267	−0.1200	0.064*
H6B	0.0664	0.8100	−0.1510	0.064*
C7	−0.2374 (2)	0.4644 (3)	−0.09854 (12)	0.0462 (7)
C8	−0.2971 (3)	0.3882 (3)	−0.15042 (14)	0.0541 (8)
C9	−0.2964 (2)	0.4523 (3)	−0.03675 (14)	0.0513 (7)
C10	0.1314 (3)	0.4501 (3)	−0.14482 (13)	0.0674 (9)
H10A	0.2197	0.4679	−0.1432	0.101*
H10B	0.1148	0.3671	−0.1725	0.101*
H10C	0.1014	0.4294	−0.1020	0.101*
C11	0.1124 (3)	0.6189 (3)	−0.23995 (11)	0.0688 (9)
H11A	0.0705	0.7042	−0.2571	0.103*
H11B	0.0961	0.5351	−0.2672	0.103*
H11C	0.2007	0.6373	−0.2384	0.103*
C12	0.0679 (2)	0.8073 (3)	−0.01057 (11)	0.0474 (7)
H12A	0.0265	0.7995	0.0288	0.057*
C13	0.1659 (2)	0.9015 (3)	−0.01442 (12)	0.0487 (7)
H13A	0.2012	0.9082	−0.0554	0.058*
C14	0.2251 (2)	0.9934 (3)	0.03385 (11)	0.0441 (7)
C15	0.1980 (2)	0.9932 (3)	0.10053 (12)	0.0470 (7)
C16	0.2659 (2)	1.0761 (3)	0.14411 (12)	0.0503 (7)
H16A	0.2468	1.0732	0.1880	0.060*
C17	0.3627 (3)	1.1635 (3)	0.12208 (13)	0.0500 (7)
C18	0.3915 (2)	1.1729 (3)	0.05700 (12)	0.0507 (7)
H18A	0.4556	1.2338	0.0426	0.061*
C19	0.3225 (2)	1.0889 (3)	0.01405 (12)	0.0469 (7)
C20	0.0710 (3)	0.8997 (3)	0.18625 (12)	0.0708 (9)
H20A	0.0020	0.8336	0.1927	0.106*
H20B	0.0484	0.9970	0.2007	0.106*
H20C	0.1419	0.8655	0.2105	0.106*
C21	0.5353 (3)	1.3159 (4)	0.15154 (13)	0.0894 (11)
H21A	0.5695	1.3647	0.1889	0.134*
H21B	0.5159	1.3880	0.1189	0.134*
H21C	0.5952	1.2469	0.1349	0.134*
C22	0.4402 (3)	1.1844 (3)	−0.07536 (12)	0.0698 (9)
H22A	0.4441	1.1751	−0.1216	0.105*
H22B	0.5188	1.1556	−0.0568	0.105*
H22C	0.4227	1.2852	−0.0641	0.105*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0710 (14)	0.0688 (12)	0.0427 (11)	−0.0252 (11)	0.0075 (10)	−0.0015 (9)
O2	0.0683 (14)	0.0987 (15)	0.0435 (12)	−0.0360 (12)	0.0040 (10)	−0.0147 (11)
O3	0.0832 (15)	0.0771 (13)	0.0399 (11)	−0.0340 (11)	0.0080 (10)	−0.0066 (9)
N1	0.077 (2)	0.088 (2)	0.0637 (18)	−0.0232 (15)	−0.0099 (15)	−0.0043 (14)
N2	0.0706 (19)	0.0879 (19)	0.0605 (17)	−0.0119 (14)	0.0111 (15)	0.0050 (14)
C1	0.0482 (18)	0.0435 (16)	0.0400 (16)	0.0007 (13)	−0.0036 (13)	0.0022 (12)
C2	0.0524 (19)	0.0552 (17)	0.0377 (16)	−0.0046 (14)	−0.0003 (14)	0.0030 (13)
C3	0.0456 (18)	0.0490 (16)	0.0382 (16)	−0.0012 (14)	−0.0062 (13)	0.0010 (13)
C4	0.054 (2)	0.0604 (18)	0.0401 (16)	−0.0031 (14)	−0.0057 (14)	−0.0011 (13)
C5	0.0523 (19)	0.0546 (17)	0.0395 (16)	−0.0051 (14)	−0.0015 (13)	−0.0036 (13)
C6	0.0565 (19)	0.0579 (18)	0.0448 (16)	−0.0066 (14)	0.0000 (14)	0.0009 (13)
C7	0.0456 (18)	0.0536 (17)	0.0393 (16)	−0.0021 (14)	−0.0078 (14)	−0.0010 (13)
C8	0.0460 (19)	0.0621 (19)	0.0541 (19)	−0.0053 (15)	−0.0027 (15)	0.0029 (16)
C9	0.0453 (19)	0.0513 (18)	0.057 (2)	−0.0085 (13)	−0.0070 (16)	0.0004 (14)
C10	0.067 (2)	0.0667 (19)	0.069 (2)	0.0056 (16)	−0.0030 (16)	−0.0097 (16)
C11	0.069 (2)	0.093 (2)	0.0443 (17)	−0.0125 (17)	0.0060 (15)	−0.0048 (15)
C12	0.0533 (19)	0.0511 (17)	0.0379 (16)	−0.0033 (14)	−0.0012 (13)	−0.0031 (13)
C13	0.0549 (19)	0.0488 (16)	0.0425 (16)	−0.0004 (15)	0.0002 (14)	0.0006 (13)
C14	0.0492 (18)	0.0452 (16)	0.0379 (16)	−0.0039 (14)	−0.0012 (13)	−0.0046 (12)
C15	0.0528 (19)	0.0450 (16)	0.0431 (17)	−0.0029 (14)	0.0002 (14)	0.0018 (13)
C16	0.0544 (19)	0.0621 (19)	0.0344 (15)	−0.0087 (15)	0.0034 (14)	0.0002 (14)
C17	0.0524 (19)	0.0565 (17)	0.0411 (17)	−0.0053 (15)	−0.0038 (15)	−0.0103 (13)
C18	0.0546 (19)	0.0549 (17)	0.0426 (17)	−0.0097 (14)	0.0066 (14)	−0.0053 (13)
C19	0.0572 (19)	0.0502 (17)	0.0334 (16)	−0.0030 (15)	0.0021 (14)	−0.0033 (13)
C20	0.087 (2)	0.075 (2)	0.0500 (18)	−0.0258 (17)	0.0180 (17)	−0.0008 (15)
C21	0.075 (2)	0.130 (3)	0.063 (2)	−0.048 (2)	0.0064 (18)	−0.0252 (19)
C22	0.090 (2)	0.072 (2)	0.0479 (18)	−0.0294 (18)	0.0142 (16)	0.0019 (15)

Geometric parameters (Å, º)

O1—C15	1.368 (3)	C10—H10B	0.960
O1—C20	1.419 (3)	C10—H10C	0.960
O2—C17	1.366 (3)	C11—H11A	0.960
O2—C21	1.418 (3)	C11—H11B	0.960
O3—C19	1.362 (3)	C11—H11C	0.960
O3—C22	1.427 (3)	C12—C13	1.355 (3)
N1—C8	1.150 (3)	C12—H12A	0.930
N2—C9	1.147 (3)	C13—C14	1.443 (3)
C1—C2	1.365 (3)	C13—H13A	0.930
C1—C12	1.437 (3)	C14—C15	1.409 (3)
C1—C6	1.506 (3)	C14—C19	1.416 (3)
C2—C3	1.423 (3)	C15—C16	1.378 (3)
C2—H2A	0.9300	C16—C17	1.382 (3)
C3—C7	1.371 (3)	C16—H16A	0.930
C3—C4	1.494 (3)	C17—C18	1.383 (3)
C4—C5	1.528 (3)	C18—C19	1.381 (3)
C4—H4A	0.9700	C18—H18A	0.930
C4—H4B	0.9700	C20—H20A	0.960
C5—C11	1.529 (3)	C20—H20B	0.960
C5—C6	1.532 (3)	C20—H20C	0.960
C5—C10	1.536 (3)	C21—H21A	0.960
C6—H6A	0.9700	C21—H21B	0.960
C6—H6B	0.9700	C21—H21C	0.960
C7—C8	1.424 (4)	C22—H22A	0.960
C7—C9	1.430 (4)	C22—H22B	0.960
C10—H10A	0.960	C22—H22C	0.960
C15—O1—C20	118.2 (2)	H11A—C11—H11C	109.5
C17—O2—C21	117.9 (2)	H11B—C11—H11C	109.5
C19—O3—C22	118.8 (2)	C13—C12—C1	123.8 (2)
C2—C1—C12	120.0 (2)	C13—C12—H12A	118.1
C2—C1—C6	119.2 (2)	C1—C12—H12A	118.1
C12—C1—C6	120.8 (2)	C12—C13—C14	131.4 (2)
C1—C2—C3	123.4 (2)	C12—C13—H13A	114.3
C1—C2—H2A	118.3	C14—C13—H13A	114.3
C3—C2—H2A	118.3	C15—C14—C19	115.9 (2)
C7—C3—C2	121.1 (2)	C15—C14—C13	125.7 (2)
C7—C3—C4	120.5 (2)	C19—C14—C13	118.3 (2)
C2—C3—C4	118.3 (2)	O1—C15—C16	122.1 (2)
C3—C4—C5	113.0 (2)	O1—C15—C14	116.0 (2)
C3—C4—H4A	109.0	C16—C15—C14	121.9 (2)
C5—C4—H4A	109.0	C15—C16—C17	119.5 (2)
C3—C4—H4B	109.0	C15—C16—H16A	120.3
C5—C4—H4B	109.0	C17—C16—H16A	120.3
H4A—C4—H4B	107.8	O2—C17—C16	114.8 (2)
C4—C5—C11	109.5 (2)	O2—C17—C18	123.6 (2)
C4—C5—C6	108.5 (2)	C16—C17—C18	121.7 (2)
C11—C5—C6	109.7 (2)	C19—C18—C17	118.0 (2)
C4—C5—C10	110.1 (2)	C19—C18—H18A	121.0
C11—C5—C10	109.1 (2)	C17—C18—H18A	121.0
C6—C5—C10	110.0 (2)	O3—C19—C18	122.2 (2)
C1—C6—C5	115.0 (2)	O3—C19—C14	114.8 (2)
C1—C6—H6A	108.5	C18—C19—C14	123.0 (2)
C5—C6—H6A	108.5	O1—C20—H20A	109.5
C1—C6—H6B	108.5	O1—C20—H20B	109.5
C5—C6—H6B	108.5	H20A—C20—H20B	109.5
H6A—C6—H6B	107.5	O1—C20—H20C	109.5
C3—C7—C8	121.8 (2)	H20A—C20—H20C	109.5
C3—C7—C9	122.3 (2)	H20B—C20—H20C	109.5
C8—C7—C9	115.9 (2)	O2—C21—H21A	109.5
N1—C8—C7	178.8 (3)	O2—C21—H21B	109.5
N2—C9—C7	179.1 (3)	H21A—C21—H21B	109.5
C5—C10—H10A	109.5	O2—C21—H21C	109.5
C5—C10—H10B	109.5	H21A—C21—H21C	109.5
H10A—C10—H10B	109.5	H21B—C21—H21C	109.5
C5—C10—H10C	109.5	O3—C22—H22A	109.5
H10A—C10—H10C	109.5	O3—C22—H22B	109.5
H10B—C10—H10C	109.5	H22A—C22—H22B	109.5
C5—C11—H11A	109.5	O3—C22—H22C	109.5
C5—C11—H11B	109.5	H22A—C22—H22C	109.5
H11A—C11—H11B	109.5	H22B—C22—H22C	109.5
C5—C11—H11C	109.5
C12—C1—C2—C3	175.9 (2)	C20—O1—C15—C16	0.4 (4)
C6—C1—C2—C3	−3.0 (4)	C20—O1—C15—C14	179.6 (2)
C1—C2—C3—C7	179.7 (2)	C19—C14—C15—O1	178.0 (2)
C1—C2—C3—C4	−2.7 (4)	C13—C14—C15—O1	−4.5 (4)
C7—C3—C4—C5	−150.4 (2)	C19—C14—C15—C16	−2.8 (4)
C2—C3—C4—C5	32.0 (3)	C13—C14—C15—C16	174.7 (2)
C3—C4—C5—C11	−172.4 (2)	O1—C15—C16—C17	179.9 (2)
C3—C4—C5—C6	−52.8 (3)	C14—C15—C16—C17	0.7 (4)
C3—C4—C5—C10	67.7 (3)	C21—O2—C17—C16	171.9 (3)
C2—C1—C6—C5	−21.2 (3)	C21—O2—C17—C18	−8.8 (4)
C12—C1—C6—C5	160.0 (2)	C15—C16—C17—O2	−179.1 (2)
C4—C5—C6—C1	47.8 (3)	C15—C16—C17—C18	1.5 (4)
C11—C5—C6—C1	167.4 (2)	O2—C17—C18—C19	179.2 (2)
C10—C5—C6—C1	−72.6 (3)	C16—C17—C18—C19	−1.5 (4)
C2—C3—C7—C8	175.7 (2)	C22—O3—C19—C18	−0.5 (4)
C4—C3—C7—C8	−1.8 (4)	C22—O3—C19—C14	180.0 (2)
C2—C3—C7—C9	−1.3 (4)	C17—C18—C19—O3	179.8 (2)
C4—C3—C7—C9	−178.8 (2)	C17—C18—C19—C14	−0.7 (4)
C2—C1—C12—C13	−176.2 (2)	C15—C14—C19—O3	−177.7 (2)
C6—C1—C12—C13	2.6 (4)	C13—C14—C19—O3	4.6 (3)
C1—C12—C13—C14	−177.1 (2)	C15—C14—C19—C18	2.8 (4)
C12—C13—C14—C15	6.6 (4)	C13—C14—C19—C18	−174.9 (2)
C12—C13—C14—C19	−176.0 (3)