5-Methyl-2-[(E)-2-(5-methyl­benz[d]oxazol-2-yl)vin­yl]benz[d]oxazole

The title compound, C₁₈H₁₄N₂O₂, was prepared by recrystallization from the fluorescent brightener135. The almost perfectly planar mol­ecule is located on a centre of inversion. The methyl H atoms are disordered equally over two positions.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.055
• wR factor = 0.155
• Data-to-parameter ratio = 15.3

checkCIF/PLATON results

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Alert level C
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

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

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Benzoxazoles are compounds having a high fluorescence and are used as optical whitening agents, photoluminescents, and active components in dye lasers (Koyama et al., 2000). Benzoxazole derivatives show antiepileptic, antispasmodic and antifungal properties (Huseyin et al., 1998).

In the title compund, the bond lengths and angles in the two oxazole rings and two benzene rings are normal (Drew et al., 1986). C9—C9A bond distance of 1.332 (4) Å shows double bond character. The whole molecular is nearly planar. There is a π-π stacking interaction between the phenyl ring and oxazole ring at x,y + 1,z. The centroid-centroid distance between the six- and five-membered ring is 3.870 Å and the perpendicular distance is 3.454 Å. In addition, there is a C—H···π interaction [C1—H1F^···cg(C2,C3,C4,C5,C6,C7)ⁱ; symmetry operator (i) x,y - 1,z] with a H^···cg distance of 3.516 Å.

Related literature

For related literature, see: Drew & Lesile (1986); Huseyin et al. (1998); Koyama et al. (2000).

S2. Experimental

The single crystals of the title compound were obtained by recrystalling the industrial product of the fluorescent whitener DT in ethanol and DMF 1:1 (v/v) for one week at room temperature.

S3. Refinement

H atoms were placed in calculated positions and treated using a riding model, with C—H = 0.93–0.98 Å and with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(C) for methyl H atoms. The methyl group is disordered over two equally occupied positions.

Computing details

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software; data reduction: CAD-4 Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL/PC (Sheldrick, 1990); software used to prepare material for publication: SHELXTL/PC.

Figures

Fig. 1. The molecular structure and atom-labeling scheme for (I), with displacement ellipsoids drawn at the 30% probability level.

5-Methyl-2-[(E)-2-(5-methylbenz[d]oxazol-2-yl)vinyl]benz[d]oxazole

Crystal data

C18H14N2O2	Dx = 1.323 Mg m^−3
Mr = 290.31	Melting point: 182 K
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 22.153 (4) Å	Cell parameters from 25 reflections
b = 4.770 (1) Å	θ = 1.9–27.0°
c = 14.053 (3) Å	µ = 0.09 mm^−1
β = 100.94 (3)°	T = 293 K
V = 1458.0 (5) Å^3	Needle, yellow
Z = 4	0.41 × 0.23 × 0.14 mm
F(000) = 608

Data collection

Bruker P4 diffractometer	Rint = 0.037
Radiation source: fine-focus sealed tube	θmax = 27.0°, θmin = 1.9°
Graphite monochromator	h = −27→26
ω scans	k = −5→0
3101 measured reflections	l = −16→16
1560 independent reflections	3 standard reflections every 200 reflections
939 reflections with I > 2σ(I)	intensity decay: none

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)] = 0.055	H-atom parameters constrained
wR(F^2) = 0.155	w = 1/[σ^2(Fo^2) + (0.0866P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max < 0.001
1560 reflections	Δρmax = 0.24 e Å^−3
102 parameters	Δρmin = −0.27 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0060 (17)

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	Occ. (<1)
O1	0.04467 (6)	0.2073 (3)	0.87972 (10)	0.0425 (5)
N1	0.10077 (8)	0.0570 (4)	1.02211 (13)	0.0403 (5)
C1	0.22548 (11)	−0.5999 (5)	0.8526 (2)	0.0560 (7)
H1A	0.2142	−0.7097	0.7947	0.084*	0.50
H1B	0.2303	−0.7206	0.9082	0.084*	0.50
H1C	0.2635	−0.5049	0.8515	0.084*	0.50
H1D	0.2579	−0.5804	0.9082	0.084*	0.50
H1E	0.2417	−0.5695	0.7947	0.084*	0.50
H1F	0.2085	−0.7853	0.8514	0.084*	0.50
C2	0.17573 (10)	−0.3866 (4)	0.85785 (17)	0.0416 (6)
C3	0.14015 (11)	−0.2845 (5)	0.77202 (18)	0.0480 (6)
H3A	0.1475	−0.3536	0.7134	0.058*
C4	0.09443 (11)	−0.0849 (5)	0.77017 (17)	0.0485 (6)
H4A	0.0710	−0.0185	0.7126	0.058*
C5	0.08615 (9)	0.0078 (5)	0.85917 (15)	0.0375 (5)
C6	0.11992 (9)	−0.0854 (4)	0.94600 (15)	0.0360 (5)
C7	0.16546 (10)	−0.2896 (4)	0.94564 (17)	0.0413 (6)
H7A	0.1882	−0.3580	1.0035	0.050*
C8	0.05734 (10)	0.2229 (5)	0.97847 (16)	0.0373 (5)
C9	0.02220 (9)	0.4192 (4)	1.02433 (16)	0.0402 (6)
H9A	0.0311	0.4336	1.0915	0.048*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0460 (9)	0.0372 (9)	0.0439 (9)	0.0071 (7)	0.0077 (6)	−0.0039 (7)
N1	0.0476 (11)	0.0308 (10)	0.0438 (10)	0.0025 (9)	0.0121 (8)	−0.0008 (8)
C1	0.0577 (15)	0.0356 (13)	0.0782 (19)	0.0041 (12)	0.0220 (13)	−0.0083 (12)
C2	0.0421 (12)	0.0247 (11)	0.0610 (15)	−0.0045 (10)	0.0173 (11)	−0.0061 (10)
C3	0.0557 (14)	0.0419 (14)	0.0491 (14)	−0.0031 (12)	0.0165 (11)	−0.0142 (11)
C4	0.0519 (14)	0.0504 (15)	0.0422 (13)	0.0027 (12)	0.0060 (10)	−0.0063 (11)
C5	0.0381 (11)	0.0303 (12)	0.0454 (12)	0.0000 (10)	0.0108 (9)	−0.0053 (10)
C6	0.0419 (12)	0.0262 (11)	0.0419 (12)	−0.0035 (10)	0.0131 (9)	−0.0025 (9)
C7	0.0441 (12)	0.0286 (12)	0.0510 (14)	0.0029 (10)	0.0087 (10)	0.0029 (10)
C8	0.0417 (11)	0.0307 (11)	0.0405 (12)	−0.0031 (10)	0.0104 (9)	−0.0028 (10)
C9	0.0457 (13)	0.0313 (12)	0.0458 (13)	−0.0021 (10)	0.0144 (10)	−0.0060 (9)

Geometric parameters (Å, º)

O1—C8	1.365 (3)	C2—C3	1.397 (3)
O1—C5	1.391 (2)	C3—C4	1.387 (3)
N1—C8	1.305 (3)	C3—H3A	0.9300
N1—C6	1.399 (3)	C4—C5	1.371 (3)
C1—C2	1.512 (3)	C4—H4A	0.9300
C1—H1A	0.9600	C5—C6	1.378 (3)
C1—H1B	0.9600	C6—C7	1.403 (3)
C1—H1C	0.9600	C7—H7A	0.9300
C1—H1D	0.9600	C8—C9	1.445 (3)
C1—H1E	0.9600	C9—C9^i	1.332 (4)
C1—H1F	0.9600	C9—H9A	0.9300
C2—C7	1.376 (3)
C8—O1—C5	103.41 (16)	C7—C2—C1	121.1 (2)
C8—N1—C6	103.80 (18)	C3—C2—C1	119.3 (2)
C2—C1—H1A	109.5	C4—C3—C2	123.1 (2)
C2—C1—H1B	109.5	C4—C3—H3A	118.5
H1A—C1—H1B	109.5	C2—C3—H3A	118.5
C2—C1—H1C	109.5	C5—C4—C3	115.3 (2)
H1A—C1—H1C	109.5	C5—C4—H4A	122.3
H1B—C1—H1C	109.5	C3—C4—H4A	122.3
C2—C1—H1D	109.5	C4—C5—C6	124.0 (2)
H1A—C1—H1D	141.1	C4—C5—O1	128.2 (2)
H1B—C1—H1D	56.3	C6—C5—O1	107.82 (17)
H1C—C1—H1D	56.3	C5—C6—N1	109.12 (18)
C2—C1—H1E	109.5	C5—C6—C7	119.39 (19)
H1A—C1—H1E	56.3	N1—C6—C7	131.5 (2)
H1B—C1—H1E	141.1	C2—C7—C6	118.5 (2)
H1C—C1—H1E	56.3	C2—C7—H7A	120.7
H1D—C1—H1E	109.5	C6—C7—H7A	120.7
C2—C1—H1F	109.5	N1—C8—O1	115.84 (19)
H1A—C1—H1F	56.3	N1—C8—C9	126.5 (2)
H1B—C1—H1F	56.3	O1—C8—C9	117.67 (19)
H1C—C1—H1F	141.1	C9^i—C9—C8	123.6 (3)
H1D—C1—H1F	109.5	C9^i—C9—H9A	118.2
H1E—C1—H1F	109.5	C8—C9—H9A	118.2
C7—C2—C3	119.6 (2)
C7—C2—C3—C4	0.6 (4)	C8—N1—C6—C7	179.4 (2)
C1—C2—C3—C4	−178.7 (2)	C3—C2—C7—C6	−1.2 (3)
C2—C3—C4—C5	0.0 (3)	C1—C2—C7—C6	178.1 (2)
C3—C4—C5—C6	0.0 (3)	C5—C6—C7—C2	1.2 (3)
C3—C4—C5—O1	179.20 (19)	N1—C6—C7—C2	−177.7 (2)
C8—O1—C5—C4	−178.4 (2)	C6—N1—C8—O1	0.2 (2)
C8—O1—C5—C6	0.9 (2)	C6—N1—C8—C9	−179.5 (2)
C4—C5—C6—N1	178.5 (2)	C5—O1—C8—N1	−0.7 (2)
O1—C5—C6—N1	−0.9 (2)	C5—O1—C8—C9	178.99 (17)
C4—C5—C6—C7	−0.7 (3)	N1—C8—C9—C9^i	−179.1 (3)
O1—C5—C6—C7	−179.99 (17)	O1—C8—C9—C9^i	1.2 (4)
C8—N1—C6—C5	0.4 (2)

Symmetry code: (i) −x, −y+1, −z+2.