Acta Cryst.(2002). E58, o1145±o1146 DOI: 10.1107/S1600536802016975 J. W. Springeret al. C18H18O4
o1145
organic papers
Acta Crystallographica Section E Structure Reports Online
ISSN 1600-5368
1,4,5,8-Tetramethoxyanthracene
J. W. Springer, T. A. Moore, A. L. Moore, Devens Gust* and Thomas L. Groy
Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604, USA
Correspondence e-mail: gust@asu.edu
Key indicators
Single-crystal X-ray study
T= 298 K
Mean(C±C) = 0.002 AÊ
Rfactor = 0.052
wRfactor = 0.140
Data-to-parameter ratio = 17.0
For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.
#2002 International Union of Crystallography Printed in Great Britain ± all rights reserved
The structure of the title compound, C18H18O4, consists of separate centrosymmetric planar molecules arranged in columns parallel to the monoclinic unique axis. The normal to the mean molecular plane lies at 55.4to the unique axis, giving adjacent columns with alternating stacking directions. The mean deviation of all non-H atoms from the least-squares molecular plane is 0.064 AÊ. Bond lengths in the aromatic rings range from 1.347 (2) to 1.440 (2) AÊ and the two unique MeÐ O bond distances are 1.418 (2) and 1.419 (2) AÊ.
Comment
There has been considerable ongoing research involving the electrochemistry of compounds incorporating multiple quinones. Some of these compounds are anthracene deriva-tives (Joze®aket al., 1989), while others are based on tripty-cene architecture (Doerneret al., 1998; Joze®ak et al., 1989; Quast & Fuchsbauer, 1986; Russell & Suleman, 1981). 1,4,5,8-Tetramethoxyanthracene (1,4,5,8-TMA), (I), has been used as an intermediate in the syntheses of some of these compounds. During research involving the synthesis of molecules that can undergo photoinduced electron transfer, 1,4,5,8-TMA was used as a synthetic intermediate.
The structure of (I) consists of individual molecules having no unusually short intermolecular contacts. The packing is in columns parallel to the b axis. Each molecule is planar, as shown in Fig. 1, with an average deviation from the least-squares plane through all non-H atoms of 0.064 AÊ, and a maximum of 0.164 AÊ by the methyl atom C30. The molecule is slightly distorted, since aromatic ring angles deviate from 120, ranging from 118.44 (13) at C2ÐC7ÐC6 to 122.27 (14) at C1ÐC7ÐC6. Perhaps the most interesting feature of this structure is the tilt of the methoxy groups. The two indepen-dent methoxy groups bend toward each other down the length of the molecule, with facing OÐCÐC angles of 113.85 (13) and 114.16 (13). Since the nearest intermolecular distances are typical of graphitic lamellar structures, these distortions are most likely due to intramolecular steric interactions between the methyl H atoms and their nearest-neighbor aromatic H atom. This type of distortion is in agreement with gas-phase molecular mechanics (MM2) calculations.
Experimental
The title compound was prepared from bromo-2,5-dimethoxy-benzene, using a synthesis developed by Fleming & Mah (1975) and re®ned by Fitzgerald et al. (1992). Their method is a one-step synthesis, using 2,2,6,6-tetramethylpiperidine in re¯uxing tetra-hydrofuran, and provides moderate yields.
Crystal data
C18H18O4
Mr= 298.32 Monoclinic,P21=n
a= 11.1715 (9) AÊ
b= 5.9994 (5) AÊ
c= 11.7159 (10) AÊ = 109.961 (2)
V= 738.05 (11) AÊ3
Z= 2
Dx= 1.342 Mg mÿ3 MoKradiation Cell parameters from 2419
re¯ections = 3.1±27.4
= 0.09 mmÿ1
T= 298 (2) K Plate, clear pale yellow 0.410.270.11 mm
Data collection
Bruker SMART APEX diffractometer !scans
Absorption correction: none 6951 measured re¯ections 1696 independent re¯ections
1159 re¯ections withI> 2(I)
Rint= 0.043
max= 27.5
h=ÿ14!14
k=ÿ7!7
l=ÿ15!15
Re®nement
Re®nement onF2
R[F2> 2(F2)] = 0.053
wR(F2) = 0.140
S= 1.01 1696 re¯ections 100 parameters
H-atom parameters constrained
w= 1/[2(F
o2) + (0.0745P)2] whereP= (Fo2+ 2Fc2)/3 (/)max< 0.001
max= 0.20 e AÊÿ3
min=ÿ0.33 e AÊÿ3
H atoms were located in difference Fourier maps, then positioned geometrically and allowed to ride on their respective parent atoms.
Data collection:SMART(Bruker, 2002); cell re®nement:SAINT (Bruker, 2002); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Bruker, 1997); program(s) used to re®ne structure:SHELXTL; molecular graphics:SHELXTL; software used to prepare material for publication:SHELXTL.
This work was supported by the US Department of Energy (DE-FG03-93ER14404). The authors express their gratitude to the National Science Foundation for their contribution toward the purchase of the single-crystal instrumentation used in this study through Award #CHE-9808440.
References
Bruker (1997). SHELXTL. Version 5.1. Bruker AXS Inc., Madison, Wisconsin, USA.
Bruker (2002).SMART(Version 5.625) andSAINT(Version 6.28A). Bruker AXS Inc., Madison, Wisconsin, USA.
Doerner, T., Gleiter, R. & Neugebauer, F. A. (1998).Eur. J. Org. Chem.pp. 1615±1623.
Fleming, I. & Mah, T. (1975).J. Chem. Soc. Perkin Trans.1, pp. 964±965. Fitzgerald, J. J., Drysdale, N. E. & Olofson, R. A. (1992).Synth. Commun.22,
1807±1812.
Joze®ak, T. H., AlmloÈf, J. E., Feyereisen, M. W. & Miller, L. L. (1989).J. Am. Chem. Soc.111, 4105±4106.
Quast, H. & Fuchsbauer, H. (1986).Chem. Ber.119, 1016±1038.
Russell, G. A. & Suleman, N. K. (1981).J. Am. Chem. Soc.103, 1561±1563.
Figure 1
supporting information
sup-1
Acta Cryst. (2002). E58, o1145–o1146supporting information
Acta Cryst. (2002). E58, o1145–o1146 [doi:10.1107/S1600536802016975]
1,4,5,8-Tetramethoxyanthracene
J. W. Springer, T. A. Moore, A. L. Moore, Devens Gust and Thomas L. Groy
S1. Comment
There has been considerable ongoing research involving the electrochemistry of compounds incorporating multiple
quinones. Some of these compounds are anthracene derivatives (Jozefiak et al., 1989), while others are based on
triptycene architecture (Doerner et al., 1998; Jozefiak et al., 1989; Quast & Fuchsbauer, 1986; Russel & Suleman, 1981).
1,4,5,8-Tetramethoxyanthracene (1,4,5,8-TMA), (I), has been used as an intermediate in the syntheses of some of these
compounds. During research involving the synthesis of molecules that can undergo photoinduced electron transfer,
1,4,5,8-TMA was used as a synthetic intermediate.
The structure of (I) consists of individual molecules having no unusually short intermolecular contacts. The packing is
in columns parallel to the b axis. Each molecule is planar, as shown in Fig. 1, with an average deviation from the
least-squares plane through all non-H atoms of 0.064 Å, and a maximum of 0.164 Å by the methyl atom C3′. The molecule is
slightly distorted, since aromatic-ring angles deviate from 120°, ranging from 118.44 (13)° at C2—C7—C6 to
122.27 (14)° at C1—C7—C6. Perhaps the most interesting feature of this structure is the tilt of the bond angles at the
methoxy groups. Both methoxy groups bend toward each other down the length of the molecule, with facing MeO-φ
angles of 113.85 (13) and 114.16 (13)°. These distortions presumably originate from packing effects in the solid state.
S2. Experimental
The title compound was prepared from bromo-2,5-dimethoxybenzene using a synthesis developed by Fleming & Mah
(1975) and refined by Olofson and co-workers (Fitzgerald et al., 1992). Their method is a one-step synthesis using
2,2,6,6-tetramethylpiperidine in refluxing tetrahydrofuran and provides moderate yields.
S3. Refinement
H atoms were located in the difference Fourier maps, then positioned geometrically and allowed to ride on their
Figure 1
Displacement ellipsoid plot shown at the 50% probability level, viewed perpendicular to the mean plane [symmetry code:
(i) 2 − x, −y, 1 − z].
1,4,5,8-tetramethoxyanthracene
Crystal data
C18H18O4 Mr = 298.32 Monoclinic, P21/n a = 11.1715 (9) Å
b = 5.9994 (5) Å
c = 11.7159 (10) Å
β = 109.961 (2)°
V = 738.05 (11) Å3 Z = 2
F(000) = 316
Dx = 1.342 Mg m−3
Mo Kα radiation, λ = 0.71073 Å Cell parameters from 2419 reflections
θ = 3.1–27.4°
µ = 0.09 mm−1 T = 298 K
Plate, clear pale yellow 0.41 × 0.27 × 0.11 mm
Data collection
Bruker SMART APEX diffractometer
ω scans
supporting information
sup-3
Acta Cryst. (2002). E58, o1145–o1146Rint = 0.043
θmax = 27.5°, θmin = 2.2° h = −14→14
k = −7→7
l = −15→15
Refinement
Refinement on F2 Least-squares matrix: full
R[F2 > 2σ(F2)] = 0.053 wR(F2) = 0.140 S = 1.01 1696 reflections 100 parameters 0 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) + (0.0745P)2] where P = (Fo2 + 2Fc2)/3 (Δ/σ)max < 0.001
Δρmax = 0.20 e Å−3 Δρmin = −0.33 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 (Å2)
x y z Uiso*/Ueq
C1 0.93841 (14) −0.0031 (2) 0.58475 (13) 0.0388 (4)
H1A 0.8971 −0.0051 0.6415 0.047*
C2 0.90694 (13) 0.1619 (2) 0.49551 (13) 0.0371 (4)
C3 0.81446 (15) 0.3322 (2) 0.48978 (14) 0.0424 (4)
O3 0.75942 (12) 0.31463 (18) 0.57774 (11) 0.0567 (4)
C3′ 0.6846 (2) 0.4977 (4) 0.5903 (2) 0.0732 (6)
H3′A 0.6511 0.4672 0.6540 0.110*
H3′B 0.6155 0.5204 0.5154 0.110*
H3′C 0.7364 0.6294 0.6100 0.110*
C4 0.78783 (15) 0.4906 (3) 0.40273 (15) 0.0485 (4)
H4A 0.7272 0.5990 0.3994 0.058*
C5 0.85135 (16) 0.4937 (3) 0.31609 (15) 0.0477 (4)
H5A 0.8320 0.6045 0.2571 0.057*
C6 0.93910 (15) 0.3381 (2) 0.31856 (13) 0.0415 (4)
O6 1.00633 (11) 0.32670 (18) 0.24022 (10) 0.0551 (4)
C6′ 0.9926 (2) 0.5070 (3) 0.15832 (18) 0.0722 (6)
H6′A 1.0438 0.4802 0.1086 0.108*
H6′B 1.0197 0.6425 0.2033 0.108*
H6′C 0.9048 0.5203 0.1077 0.108*
Atomic displacement parameters (Å2)
U11 U22 U33 U12 U13 U23
C1 0.0413 (8) 0.0408 (8) 0.0347 (8) −0.0050 (7) 0.0135 (6) −0.0012 (6)
C2 0.0368 (8) 0.0358 (8) 0.0354 (8) −0.0044 (6) 0.0079 (6) −0.0018 (6)
C3 0.0399 (8) 0.0430 (9) 0.0418 (9) −0.0025 (7) 0.0106 (7) −0.0049 (7)
O3 0.0601 (8) 0.0581 (8) 0.0593 (8) 0.0124 (6) 0.0302 (6) 0.0023 (6)
C3′ 0.0627 (13) 0.0778 (14) 0.0891 (15) 0.0194 (10) 0.0387 (11) −0.0018 (11)
C4 0.0454 (9) 0.0423 (9) 0.0515 (10) 0.0081 (7) 0.0083 (8) 0.0007 (8)
C5 0.0524 (10) 0.0401 (9) 0.0430 (9) 0.0014 (7) 0.0067 (7) 0.0087 (7)
C6 0.0442 (9) 0.0418 (9) 0.0344 (8) −0.0064 (7) 0.0079 (7) 0.0029 (7)
O6 0.0641 (8) 0.0575 (8) 0.0474 (7) 0.0045 (6) 0.0236 (6) 0.0171 (5)
C6′ 0.0966 (16) 0.0706 (12) 0.0534 (11) 0.0009 (11) 0.0307 (11) 0.0245 (10)
C7 0.0376 (8) 0.0360 (8) 0.0324 (7) −0.0062 (6) 0.0060 (6) −0.0012 (6)
Geometric parameters (Å, º)
C1—C7i 1.388 (2) C4—C5 1.423 (2)
C1—C2 1.395 (2) C5—C6 1.347 (2)
C2—C7 1.423 (2) C6—O6 1.3717 (19)
C2—C3 1.438 (2) C6—C7 1.440 (2)
C3—C4 1.351 (2) O6—C6′ 1.4191 (19)
C3—O3 1.3725 (19) C7—C1i 1.388 (2)
O3—C3′ 1.418 (2)
C7i—C1—C2 121.85 (13) C6—C5—C4 120.80 (14)
C1—C2—C7 118.87 (13) C5—C6—O6 125.51 (14)
C1—C2—C3 122.17 (14) C5—C6—C7 120.65 (14)
C7—C2—C3 118.95 (13) O6—C6—C7 113.84 (13)
C4—C3—O3 125.55 (14) C6—O6—C6′ 117.18 (14)
C4—C3—C2 120.31 (15) C1i—C7—C2 119.27 (13)
O3—C3—C2 114.15 (13) C1i—C7—C6 122.27 (14)
C3—O3—C3′ 116.71 (14) C2—C7—C6 118.44 (13)
C3—C4—C5 120.85 (14)