c 2,t 4 Bis(2 benzoxazol 2 yl) r 1,t 3 bis­­[4 (di­methyl­amino)phen­yl]cyclo­butane

organic papers

Acta Cryst.(2007). E63, o1171–o1172 doi:10.1107/S1600536807004813 Liet al. _C

34H32N4O2

o1171

Acta Crystallographica Section E Structure Reports

Online

ISSN 1600-5368

c

-2,

t

-4-Bis(2-benzoxazol-2-yl)-

r

-1,

t

-3-bis[4-(dimethylamino)phenyl]cyclobutane

Feng-Yu Li, Shu-Tao Wang, Jun-Peng Zhuang, Lei Jiang and Yan-Lin Song*

Key Laboratory of Organic Solids, Institute of Chemistry and Centre for Molecular Science, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China

Correspondence e-mail: ylsong@iccas.ac.cn

Key indicators

Single-crystal X-ray study T= 293 K

Mean(C–C) = 0.005 A˚ Rfactor = 0.064 wRfactor = 0.218

Data-to-parameter ratio = 13.5

For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.

Received 29 December 2006 Accepted 30 January 2007

#2007 International Union of Crystallography All rights reserved

The title compound, C34H32N4O2, undergoes a reversible [2+2]

photoreaction with 1-(2-benzoxazol-2-yl)-2-bis[4-(dimethyl-amino)phenyl]ethane (NBE). Through intermolecular head-to-tail [2+2] photocycloaddition of NBE, the title compound displays a centrosymmetric molecular structure in the crystal-line state. The cyclobutane ring has an exactly planar conformation and is nearly square.

Comment

Utilizing the two distinct isomeric states of [2+2] photo-reaction between diarylethenes and tetraarylcyclobutanes, tetraarylcyclobutanes can be applied as optical data-storage materials. The molecular structure of tetraarylcyclobutane enables the study of the mechanism of action of such storage materials and the improvement of their properties. An average puckered conformation of the cyclobutane ring is found in tetraarylcyclobutanes such asr-1,c-2,t-3,t -4-1,3-bis[2-(4-R-phenyl)]-2,4-di(4-pyridyl)-cyclobutane, withR= Cl, CH3

and C6H5(Busettiet al., 1980; Zhang, Liet al., 2000). However,

a planar conformation of the cyclobutane ring has been observed in some tetraheteroaryl- and diphenylbisheteroaryl-substituted cyclobutanes, such as r-1,c-2,t-3,t -4-tetrakis-(2-R)cyclobutane, with R = 6,7-dimethylbenzoxazolyl, 5-phenyloxazolyl and benzoxazolyl (Kaoet al., 1989; Zhanget al., 1996; Zhang, Zhanget al., 2000), andr-1,c-2,t-3,t

-4-1,3-bis-R-2,4-bis(4-methoxyphenyl)cyclobutane, with R = 5-methyl-benzoxazolyl and 2-(5-phenyl-1,3,4-oxadiazolyl) (Zhanget al., 2001; Zhenget al., 2001). The title compound, (I), has a head-to-tail structure, and the cyclobutane ring has a planar conformation.

bond angles in the centrosymmetric cyclobutane ring of (I) are 90.8 (2) and 89.2 (2)_{. The C—C bonds of the cyclobutane ring}

are equal in length [1.577 (4) A˚ ], and although this is longer than a normal C—C single bond, this elongation is common for cyclobutanes (Zhenget al., 2001; Zhuanget al., 2002).

The benzoxazolyl group is planar, while the benzeneamine group is nearly planar, with a slight twist between the benzene and dimethylamine groups of 5.8 (7)_{, demonstrating that the}

lone electron pair of the N atom is not completely conjugated with thesystem of the aryl group when there is no acceptor group at the opposite position of the benzene ring. The dihedral angle between the benzoxazolyl and benzeneamine planes, which are situated on the same side of the cyclobutane ring, is 59.38 (12)_{, and the dihedral angles between the}

cyclobutane ring plane and the benzoxazolyl and benzene-amine planes are 87.50 (12) and 44.56 (11)_{, respectively.}

Experimental

A solution of 4-(dimethylamino)benzaldehyde hydrochloride (1.86 g, 0.01 mol) and 2-methylbenzooxazole (1.80 ml, 0.015 mol) in dimethylformamide (50 ml) was stirred at 353 K. KOH (5.0 g, 0.089 mol) was added to the reaction mixture over a period of 1 h. After 4 h, the mixture was added quickly to water (100 ml) and a precipitate was obtained. Recrystallization from ethanol gave yellow needle crystals of 1-(N,N -dimethyl-4-benzeneamino)-2-(2-benzoxazolyl)ethane (NBE) (2.2 g, 84%). A solution of NBE (50 mg) in acetonitrile (80 ml) was placed under a 300 W high-pressure

cooled in a refrigerator overnight and then filtered to isolate the precipitate. Recrystallization from a solution in a dimethyl-formamide-ethanol mixture (1:1) gave single crystals of (I).

Crystal data

C34H32N4O2

Mr= 528.64

Monoclinic,C2=c a= 24.441 (5) A˚

b= 6.0694 (12) A˚

c= 20.101 (4) A˚

= 108.46 (3)

V= 2828.4 (10) A˚3

Z= 4

Dx= 1.241 Mg m 3

MoKradiation

= 0.08 mm 1

T= 293 (2) K Rod, colourless 0.440.350.21 mm

Data collection

Rigaku R-AXIS RAPID image-plate diffractometer

!scans

Absorption correction: none 12682 measured reflections

2476 independent reflections 1549 reflections withI> 2(I)

Rint= 0.037

max= 25.0

Refinement

Refinement onF2

R[F2> 2(F2)] = 0.064

wR(F2_{) = 0.218}

S= 1.02 2476 reflections 183 parameters

H-atom parameters constrained

w= 1/[2

(Fo2) + (0.1378P)2]

whereP= (Fo2+ 2Fc2)/3

(/)max< 0.001

max= 0.32 e A˚ 3

min= 0.41 e A˚ 3

Methyl H atoms were placed in calculated positions, with C—H = 0.96 A˚ , their torsion angles were refined to fit the electron density, andUiso(H) = 1.5Ueq(C). Other H atoms were placed in calculated positions, with C—H = 0.93 (aromatic) or 0.98 A˚ (methine), and refined in riding mode, withUiso(H) = 1.2Ueq(C).

Data collection:RAPID-AUTO (Rigaku, 1998); cell refinement:

RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure:SHELXL97(Sheldrick, 1997); molecular graphics:SHELXTL(Bruker, 2002); software used to prepare material for publication:SHELXTL.

We thank Dr Hong-Wei Ma of the Institute of Chemistry, Chinese Academy of Sciences, for collecting the intensity data.

References

Bruker (2002).SHELXTL. Bruker AXS Inc., Madison, Wisconsin, USA. Busetti, V., Valle, G., Zanotti, G. & Galiazzo, G. (1980).Acta Cryst.B36, 894–

897.

Kao, C. H., Zhou, Y. M., Xia, X. P., Wang, H. G. & Wang, R. J. (1989).J. Struct. Chem.8, 53–56.

Rigaku (1998).PROCESS-AUTO. Rigaku Corporation, Tokyo, Japan. Rigaku/MSC (2002).CrystalStructure. Version 3.00. Rigaku/MSC, The

Wood-lands, Texas, USA.

Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Go¨ttingen, Germany.

Zhang, W. Q., Li, S. L., Zhang, Z. M., Qi, X., Zheng, Y., Zhuang, J. P. & Mak, T. C. W. (2000).Chem. J. Chin. Univ.21, 556–561.

Zhang, W. Q., Wang, M. Z. & Wang, H. G. (1996).Sci. China Ser. B,39, 105– 112.

Zhang, W. Q., Zhang, Z. M., Zheng, Y., Wang, S. L. & Zhao, S. N. (2000).Acta Phys. Chim. Sin.16, 207–213.

Zhang, W. Q., Zhuang, J. P., Li, C. B., Sun, H. & Yuan, X. N. (2001).Chin. J. Chem. .19, 695–701.

Zheng, Y., Zhuang, J.-P., Zhang, W.-Q., Leng, X.-B. & Weng, L.-H. (2001).Acta

Figure 1

The molecular structure of (I), with 30% probability displacement ellipsoids (arbitrary spheres for the H atoms). [Symmetry code: (A)1

2 x, 3

supporting information

sup-1 Acta Cryst. (2007). E63, o1171–o1172

supporting information

Acta Cryst. (2007). E63, o1171–o1172 [https://doi.org/10.1107/S1600536807004813]

c

-2,

t

-4-Bis(2-benzoxazol-2-yl)-

r

-1,

t

-3-bis[4-(dimethylamino)phenyl]cyclobutane

Feng-Yu Li, Shu-Tao Wang, Jun-Peng Zhuang, Lei Jiang and Yan-Lin Song

r-1,c-2,t-3,t-4–1,3-bis(N,N-dimethyl-4-benzenamino)-2,4-bis- (2-benzooxzolyl)cyclobutane

Crystal data

C34H32N4O2 Mr = 528.64

Monoclinic, C2/c

Hall symbol: -C 2yc

a = 24.441 (5) Å

b = 6.0694 (12) Å

c = 20.101 (4) Å

β = 108.46 (3)°

V = 2828.4 (10) Å3

Z = 4

F(000) = 1120

Dx = 1.241 Mg m−3

Melting point: 548(1) K

Mo Kα radiation, λ = 0.71073 Å

Cell parameters from 12682 reflections

θ = 2.3–25.0°

µ = 0.08 mm−1

T = 293 K

Platelet, colourless 0.44 × 0.35 × 0.21 mm

Data collection

Rigaku R-AXIS RAPID image-plate diffractometer

Radiation source: fine-focus sealed tube Graphite monochromator

ω scans

12682 measured reflections 2476 independent reflections

1549 reflections with I > 2σ(I)

Rint = 0.037

θmax = 25.0°, θmin = 1.7°

h = −28→28

k = −7→7

l = −23→22

Refinement

Refinement on F2

Least-squares matrix: full

R[F2 _{> 2σ(F}2_{)] = 0.064} wR(F2_{) = 0.218}

S = 1.02

2476 reflections 183 parameters 18 restraints

Primary atom site location: structure-invariant direct methods

Secondary atom site location: difference Fourier map

Hydrogen site location: inferred from neighbouring sites

H-atom parameters constrained

w = 1/[σ2_(F

o2) + (0.1378P)2]

where P = (Fo2 + 2Fc2)/3

(Δ/σ)max < 0.001

Δρmax = 0.32 e Å−3

Δρmin = −0.41 e Å−3

Special details

Experimental. 1-(N,N-dimethyl-4-benzenamino)-2-(2-benzooxazolyl)ethane: 1_{H NMR (300 MHz, CDCl}

3, δ, p.p.m.):

7.76–7.26 (7H, m), 6.88–6.71 (3H, m), 3.03 (6H, s); 13_{C NMR (300 MHz, CDCl}

3, δ, p.p.m.): 163.2, 150.6, 149.6, 141.7,

139.2, 128.3, 124.1, 123.7, 118.6, 111.3, 109.3, 107.8, 39.5.

The title compound: 1_{H NMR (300 MHz, CDCl}

3, δ, p.p.m.): 7.65–7.18 (6H, m), 6.53 (2H, d), 4.93 (1H, t), 4.77 (1H, t),

2.80 (6H, s); 13_{C NMR (300 MHz, CDCl}

3, δ, p.p.m.): 165.1, 150.2, 148.7, 140.4, 127.3, 123.5, 123.0, 118.8, 111.8, 109.5,

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 F}2_,

conventional R-factors R are based on F, with F set to zero for negative F2_{. The threshold expression of F}2 _{> σ(F}2_{) 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₎

x y z Uiso*/Ueq

N1 0.12010 (11) 0.8052 (4) 0.42964 (14) 0.0633 (7)

O1 0.14612 (9) 1.1341 (4) 0.47938 (11) 0.0674 (6)

N2 0.36330 (13) 0.8422 (5) 0.24634 (14) 0.0779 (9)

C1 0.08670 (12) 1.1275 (5) 0.45478 (15) 0.0571 (8)

C2 0.04860 (16) 1.2903 (7) 0.4566 (2) 0.0839 (11)

H2A 0.0606 1.4271 0.4768 0.101*

C3 −0.00897 (17) 1.2375 (8) 0.4265 (2) 0.0902 (12)

H3A −0.0367 1.3419 0.4268 0.108*

C4 −0.02618 (16) 1.0406 (8) 0.3967 (2) 0.0902 (12)

H4A −0.0655 1.0124 0.3775 0.108*

C5 0.01267 (15) 0.8786 (7) 0.3937 (2) 0.0877 (11)

H5A 0.0006 0.7439 0.3720 0.105*

C6 0.07010 (13) 0.9273 (5) 0.42462 (15) 0.0598 (8)

C7 0.16147 (12) 0.9337 (5) 0.46173 (14) 0.0547 (7)

C8 0.22512 (12) 0.8992 (5) 0.48027 (14) 0.0580 (8)

H8A 0.2444 1.0338 0.4724 0.070*

C9 0.24309 (12) 0.7011 (5) 0.44503 (14) 0.0560 (8)

H9A 0.2090 0.6119 0.4217 0.067*

C10 0.27671 (11) 0.7423 (5) 0.39464 (14) 0.0537 (7)

C11 0.27387 (14) 0.5949 (6) 0.34313 (17) 0.0664 (9)

H11A 0.2516 0.4687 0.3399 0.080*

C12 0.30281 (14) 0.6255 (5) 0.29555 (17) 0.0675 (9)

H12A 0.3000 0.5182 0.2616 0.081*

C13 0.33623 (12) 0.8109 (5) 0.29618 (13) 0.0528 (7)

C14 0.34013 (13) 0.9618 (5) 0.34893 (16) 0.0645 (8)

H14A 0.3627 1.0873 0.3523 0.077*

C15 0.31056 (13) 0.9282 (6) 0.39711 (15) 0.0666 (9)

H15A 0.3136 1.0330 0.4318 0.080*

C16 0.3976 (2) 1.0327 (8) 0.2478 (2) 0.1156 (17)

H16A 0.3761 1.1620 0.2517 0.173*

H16B 0.4076 1.0401 0.2054 0.173*

H16C 0.4321 1.0247 0.2874 0.173*

C17 0.3640 (2) 0.6713 (8) 0.1978 (2) 0.1190 (17)

H17A 0.3259 0.6117 0.1783 0.179*

H17B 0.3899 0.5568 0.2217 0.179*

supporting information

sup-3 Acta Cryst. (2007). E63, o1171–o1172

Atomic displacement parameters (Å2₎

U11 _U22 _U33 _U12 _U13 _U23

N1 0.0584 (16) 0.0588 (15) 0.0689 (15) 0.0188 (13) 0.0146 (13) 0.0009 (13)

O1 0.0541 (13) 0.0771 (14) 0.0686 (13) 0.0112 (11) 0.0159 (10) −0.0074 (11)

N2 0.0839 (19) 0.097 (2) 0.0650 (16) −0.0009 (17) 0.0405 (15) −0.0067 (15)

C1 0.0479 (17) 0.074 (2) 0.0506 (16) 0.0117 (15) 0.0171 (13) 0.0014 (15)

C2 0.075 (2) 0.088 (3) 0.088 (2) 0.025 (2) 0.024 (2) −0.012 (2)

C3 0.065 (2) 0.114 (3) 0.095 (3) 0.041 (2) 0.031 (2) 0.014 (3)

C4 0.0455 (19) 0.117 (3) 0.102 (3) 0.012 (2) 0.0138 (19) 0.022 (3)

C5 0.052 (2) 0.090 (3) 0.107 (3) 0.0029 (19) 0.0065 (19) 0.004 (2)

C6 0.0522 (18) 0.070 (2) 0.0568 (17) 0.0109 (16) 0.0171 (14) 0.0099 (16)

C7 0.0494 (17) 0.0718 (19) 0.0456 (15) 0.0140 (16) 0.0187 (13) 0.0099 (15)

C8 0.0575 (18) 0.0590 (16) 0.0585 (17) 0.0032 (14) 0.0200 (14) −0.0032 (14)

C9 0.0506 (16) 0.0630 (18) 0.0513 (15) −0.0011 (14) 0.0116 (13) −0.0087 (14)

C10 0.0409 (14) 0.0688 (18) 0.0465 (14) 0.0040 (14) 0.0070 (11) −0.0022 (14)

C11 0.067 (2) 0.0685 (19) 0.0654 (19) −0.0003 (16) 0.0230 (16) −0.0077 (17)

C12 0.070 (2) 0.073 (2) 0.0643 (18) 0.0007 (17) 0.0280 (16) −0.0183 (16)

C13 0.0476 (15) 0.0653 (18) 0.0449 (15) 0.0118 (14) 0.0141 (12) −0.0010 (14)

C14 0.0579 (19) 0.072 (2) 0.0640 (18) −0.0064 (16) 0.0204 (15) −0.0140 (17)

C15 0.0614 (19) 0.086 (2) 0.0489 (15) 0.0082 (17) 0.0133 (13) −0.0220 (16)

C16 0.140 (4) 0.129 (4) 0.100 (3) −0.037 (3) 0.070 (3) −0.002 (3)

C17 0.165 (5) 0.124 (4) 0.101 (3) −0.007 (3) 0.089 (3) −0.033 (3)

Geometric parameters (Å, º)

N1—C7 1.278 (4) C8—H8A 0.9800

N1—C6 1.405 (4) C9—C10 1.514 (4)

O1—C7 1.353 (4) C9—C8i _{1.578 (4)}

O1—C1 1.379 (4) C9—H9A 0.9800

N2—C13 1.378 (4) C10—C11 1.354 (4)

N2—C16 1.423 (5) C10—C15 1.390 (4)

N2—C17 1.428 (5) C11—C12 1.370 (4)

C1—C6 1.361 (4) C11—H11A 0.9300

C1—C2 1.366 (4) C12—C13 1.388 (4)

C2—C3 1.382 (6) C12—H12A 0.9300

C2—H2A 0.9300 C13—C14 1.382 (4)

C3—C4 1.343 (6) C14—C15 1.395 (4)

C3—H3A 0.9300 C14—H14A 0.9300

C4—C5 1.381 (5) C15—H15A 0.9300

C4—H4A 0.9300 C16—H16A 0.9600

C5—C6 1.375 (5) C16—H16B 0.9600

C5—H5A 0.9300 C16—H16C 0.9600

C7—C8 1.495 (4) C17—H17A 0.9600

C8—C9 1.529 (4) C17—H17B 0.9600

C8—C9i _{1.578 (4) C17—H17C 0.9600}

C7—O1—C1 103.2 (2) C10—C9—H9A 109.3

C13—N2—C16 120.8 (3) C8—C9—H9A 109.3

C13—N2—C17 120.6 (3) C8i_{—C9—H9A 109.3}

C16—N2—C17 118.1 (3) C11—C10—C15 116.7 (3)

C6—C1—C2 123.2 (3) C11—C10—C9 119.7 (3)

C6—C1—O1 108.5 (2) C15—C10—C9 123.6 (3)

C2—C1—O1 128.2 (3) C10—C11—C12 122.1 (3)

C1—C2—C3 115.4 (4) C10—C11—H11A 119.0

C1—C2—H2A 122.3 C12—C11—H11A 119.0

C3—C2—H2A 122.3 C11—C12—C13 122.4 (3)

C4—C3—C2 122.2 (3) C11—C12—H12A 118.8

C4—C3—H3A 118.9 C13—C12—H12A 118.8

C2—C3—H3A 118.9 N2—C13—C14 122.3 (3)

C3—C4—C5 122.0 (4) N2—C13—C12 121.4 (3)

C3—C4—H4A 119.0 C14—C13—C12 116.2 (3)

C5—C4—H4A 119.0 C13—C14—C15 120.7 (3)

C6—C5—C4 116.4 (4) C13—C14—H14A 119.6

C6—C5—H5A 121.8 C15—C14—H14A 119.6

C4—C5—H5A 121.8 C10—C15—C14 121.8 (3)

C1—C6—C5 120.7 (3) C10—C15—H15A 119.1

C1—C6—N1 108.0 (3) C14—C15—H15A 119.1

C5—C6—N1 131.3 (3) N2—C16—H16A 109.5

N1—C7—O1 116.1 (2) N2—C16—H16B 109.5

N1—C7—C8 129.4 (3) H16A—C16—H16B 109.5

O1—C7—C8 114.4 (3) N2—C16—H16C 109.5

C7—C8—C9 115.0 (3) H16A—C16—H16C 109.5

C7—C8—C9i _{116.8 (2) H16B—C16—H16C 109.5}

C9—C8—C9i _{90.6 (2) N2—C17—H17A 109.5}

C7—C8—H8A 111.0 N2—C17—H17B 109.5

C9—C8—H8A 111.0 H17A—C17—H17B 109.5

C9i_{—C8—H8A 111.0 N2—C17—H17C 109.5}

C10—C9—C8 118.4 (3) H17A—C17—H17C 109.5

C10—C9—C8i _{119.5 (2) H17B—C17—H17C 109.5}

C7—O1—C1—C6 0.2 (3) C7—C8—C9—C10 116.2 (3)

C7—O1—C1—C2 −177.8 (3) C9i_{—C8—C9—C10 −123.7 (3)}

C6—C1—C2—C3 1.0 (5) C7—C8—C9—C8i _{−120.2 (3)}

O1—C1—C2—C3 178.8 (3) C9i_{—C8—C9—C8}i _0.0

C1—C2—C3—C4 −0.7 (6) C8—C9—C10—C11 −153.9 (3)

C2—C3—C4—C5 −0.7 (6) C8i_{—C9—C10—C11 99.1 (3)}

C3—C4—C5—C6 1.7 (6) C8—C9—C10—C15 25.1 (4)

C2—C1—C6—C5 0.1 (5) C8i_{—C9—C10—C15 −81.9 (4)}

O1—C1—C6—C5 −178.1 (3) C15—C10—C11—C12 0.1 (5)

C2—C1—C6—N1 177.6 (3) C9—C10—C11—C12 179.1 (3)

O1—C1—C6—N1 −0.6 (3) C10—C11—C12—C13 −1.0 (5)

C4—C5—C6—C1 −1.4 (5) C16—N2—C13—C14 0.9 (5)

C4—C5—C6—N1 −178.3 (3) C17—N2—C13—C14 172.5 (4)

supporting information

sup-5 Acta Cryst. (2007). E63, o1171–o1172

C7—N1—C6—C5 177.8 (3) C17—N2—C13—C12 −8.2 (5)

C6—N1—C7—O1 −0.6 (3) C11—C12—C13—N2 −177.6 (3)

C6—N1—C7—C8 −177.6 (3) C11—C12—C13—C14 1.7 (5)

C1—O1—C7—N1 0.2 (3) N2—C13—C14—C15 177.8 (3)

C1—O1—C7—C8 177.7 (2) C12—C13—C14—C15 −1.5 (4)

N1—C7—C8—C9 11.8 (4) C11—C10—C15—C14 0.1 (5)

O1—C7—C8—C9 −165.3 (2) C9—C10—C15—C14 −178.9 (3)

N1—C7—C8—C9i _{−92.6 (3) C13—C14—C15—C10 0.7 (5)}

O1—C7—C8—C9i _{90.3 (3)}