A [4π+4π] intramolecular photocyclomer of 9-anthroic anhydride: 5,6,11,12-tetrahydro-5,12;6,11-di-o-­benzenodibenzo[a,e]cyclooctene-5,6-dicarboxylic anhydride

The title compound, C₃₀H₁₈O₃, was obtained by light irradiation of a di­chloro­ethane solution of 9-anthroyl chloride and 9-anthroic acid. The mol­ecules, which possess approximately mm2 local symmetry, are packed in columns, the oxy­genated moieties facing each other according to the symmetry of a monoclinic lattice. The space group of the crystal is P2₁/c, with a whole mol­ecule as the asymmetric unit. The structure is compared with those of similar dianthracene derivatives.

S1. Comment

The title compound, (I), was first obtained by sunlight irradiation of a solution of 9-anthroic anhydride (Greene et al., 1955). In the course of the preparation of some anthroyl-functionalized derivatives β-ketoenolato of rhodium(III) and iridium(III) (Carano et al., 2002), we have found that (I) is formed as a by-product of the reaction between Rh(acac)₃ or Ir(acac)₃ (acac is pentane-2,4-dionato) and 9-anthroyl chloride in the presence of AlCl₃. The genesis of (I) is easily rationalized according to the reactions outlined in the reaction Scheme below, which imply the presence of 9-anthroic acid as an impurity. Indeed, the ¹H NMR spectrum of the mixture resulting from the reaction of 9-anthroyl chloride with 9-anthroic acid, at 253 K in the presence of AlCl₃, indicated the presence of 9-anthroic anhydride. Exposure of this solution to sunlight resulted in the slow deposition of well shaped crystals of (I). Since the compounds resulting from the [4π + 4π] cycloaddition of two anthracene moieties are currently of great interest (Becker, 1993; Bouas-Laurent et al., 2000), we characterized (I) by single-crystal X-ray analysis. \sch

The molecular structure of (I) is shown in Fig. 1, and bond distances and angles are listed in Table 1. The geometric parameters of the aromatic moiety are very similar to those already reported for 9,9':10,10'-dianthracene (Ehrenberg, 1966; Choi & Marinkas, 1980; Abboud et al., 1990). Indeed, very long C1—C15 and C8—C22 bonds [1.614 (5) and 1.612 (5) Å, respectively] are observed, along with the bending of the anthrylidene moieties as a result of the sp³ hybridization of atoms C1, C8, C15, and C22. The two anthrylidene moieties of (I) show a difference in bending of 130.8 (1) and 134.9 (1)°, respectively. Slightly different dihedral angles are also observed between the C1—C8 and C15—C22 planes [47.6 (1)°] and between the C8—C14,C1 and C22—C28,C15 planes [46.7 (1)°]. These differences, which probably arise from the packing forces, reduce the mm2 molecular symmetry. Similar distortions are found in other dianthracene derivatives in which the C1—C15 bond is shared with a condensed five- [(II); Noe et al., 1994] or four-membered ring [(III); Becker et al., 1991] (see Scheme below).

Within this class of compounds, the maximum crystallographic symmetry has been observed only in the molecular structure of 9,9':10,10'-dianthracene, which is centrosymmetric. Atoms C1 and C15 of (I) are part of an almost perfectly planar (maximum deviation 0.01 Å) oxacyclopentanedione ring (anhydride) whose geometrical parameters, apart from the unusual length of the C1—C15 bond, are very similar to those of succinic anhydride (Ehrenberg, 1965; Biagini & Cannas, 1965; Fodor et al., 1984).

The crystal structure of (I), shown in Fig. 2, is built up of double columns of molecules growing in the a direction. The molecules along the double columns are related by inversion centres [Wyckoff position 2(c)] which force the oxygenated moieties to face each other. As atom O2, which occupies the central position in the molecule, is placed at x = 0.7516 (3), the molecules along the double columns are spanned by almost exactly a/2. In the other two directions, as shown in Fig. 2, the double columns are disposed as a herring bone. Almost all the intermolecular contacts are greater than or equal to the sum of the van der Waals radii of the atoms involved (Reference?), with the sole exception of the distance between atoms O3 and H24, i.e. the H atom linked to atom C24 (Table 2). This short contact, although corresponding to a weak interaction, is probably of some relevance in the packing.

S2. Experimental

Compound (I) is a by-product of the reaction of M(acac)₃ (M = Rh or Ir) with 9-anthroyl chloride and AlCl₃ at 253 K, in dichloroehane. The reaction mixture was treated with aqueous HCl 10%, at 273 K. The organic layer was then separated and dried over anhydrous Na2SO4. By evaporation of the volatiles under vacuum a solid residue was obtained which was dissolved in CH2Cl2. Well shaped crystals of (I) were formed from the resulting solution by slow evaporation of the solvent at room temperature.

S3. Refinement

All H atoms were found in the electron-density difference map and their parameters were refined without constraints. The crystals, although well shaped, were rather small and poorly diffracting, so the 2θ_max of the collection was limited to 51°; notwithstanding this limit, the observed reflections were only 46%. The results are presented anyway, taking into account the interest in (I) from a chemical point of view.

Computing details

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: SHELXTL (Sheldrick, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL; software used to prepare material for publication: WinGX1.64 (Farrugia, 1999).

Figures

	Fig. 1. A view of the structure of (I) showing 30% probability displacement ellipsoids. H atoms are drawn as small spheres of arbitrary radii.
	Fig. 2. A view of the crystal packing in (I) projected down a. A double column is shown in bold.

5,6,11,12-tetrahydro-5,12;6,11-di-o-benzenodibenzo[a,e]cyclooctene- 5,6-dicarboxylic anhydride

Crystal data

C30H18O3	F(000) = 888
Mr = 426.44	Dx = 1.372 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 22 reflections
a = 10.1635 (17) Å	θ = 6.3–17.1°
b = 17.038 (3) Å	µ = 0.09 mm^−1
c = 12.547 (3) Å	T = 293 K
β = 108.155 (13)°	Prism flattened on (1 0 0), colourless
V = 2064.5 (7) Å^3	0.35 × 0.32 × 0.11 mm
Z = 4

Data collection

Bruker P4 diffractometer	θmax = 25.5°, θmin = 2.1°
Graphite monochromator	h = −10→12
2θ/ω scans	k = −1→20
4826 measured reflections	l = −15→14
3822 independent reflections	3 standard reflections every 97 reflections
1769 reflections with I > 2σ(I)	intensity decay: none
Rint = 0.050

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)] = 0.066	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.138	All H-atom parameters refined
S = 0.98	w = 1/[σ^2(Fo^2) + (0.0455P)^2] where P = (Fo^2 + 2Fc^2)/3
3822 reflections	(Δ/σ)max = 0.001
370 parameters	Δρmax = 0.17 e Å^−3
0 restraints	Δρmin = −0.22 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
C1	0.7077 (3)	0.04717 (19)	0.3010 (3)	0.0325 (9)
C2	0.5666 (4)	0.0402 (2)	0.2091 (3)	0.0367 (9)
C3	0.4694 (4)	−0.0169 (2)	0.2077 (3)	0.0416 (10)
C4	0.3441 (4)	−0.0184 (3)	0.1199 (3)	0.0500 (11)
C5	0.3190 (4)	0.0367 (3)	0.0358 (3)	0.0496 (11)
C6	0.4149 (4)	0.0939 (3)	0.0378 (3)	0.0439 (10)
C7	0.5399 (3)	0.0967 (2)	0.1240 (3)	0.0347 (9)
C8	0.6493 (4)	0.1582 (2)	0.1313 (3)	0.0382 (9)
C9	0.7875 (3)	0.1174 (2)	0.1588 (3)	0.0338 (9)
C10	0.8846 (4)	0.1337 (2)	0.1045 (3)	0.0421 (10)
C11	1.0098 (4)	0.0944 (3)	0.1351 (4)	0.0536 (12)
C12	1.0402 (5)	0.0395 (3)	0.2189 (4)	0.0537 (12)
C13	0.9450 (4)	0.0220 (2)	0.2739 (3)	0.0422 (10)
C14	0.8196 (3)	0.0603 (2)	0.2442 (3)	0.0341 (9)
C15	0.7060 (3)	0.1150 (2)	0.3903 (3)	0.0335 (9)
C16	0.5656 (4)	0.1564 (2)	0.3621 (3)	0.0351 (9)
C17	0.4638 (4)	0.1397 (3)	0.4108 (3)	0.0480 (11)
C18	0.3380 (5)	0.1771 (3)	0.3752 (4)	0.0596 (13)
C19	0.3129 (4)	0.2336 (3)	0.2925 (4)	0.0560 (12)
C20	0.4138 (4)	0.2508 (2)	0.2434 (3)	0.0465 (11)
C21	0.5402 (3)	0.2124 (2)	0.2766 (3)	0.0358 (9)
C22	0.6509 (4)	0.2261 (2)	0.2213 (3)	0.0350 (9)
C23	0.7897 (4)	0.2318 (2)	0.3122 (3)	0.0344 (9)
C24	0.8885 (4)	0.2875 (2)	0.3108 (3)	0.0428 (10)
C25	1.0169 (4)	0.2875 (3)	0.3935 (4)	0.0491 (11)
C26	1.0459 (4)	0.2317 (3)	0.4778 (4)	0.0472 (11)
C27	0.9471 (4)	0.1766 (2)	0.4803 (3)	0.0413 (10)
C28	0.8189 (3)	0.1756 (2)	0.3987 (3)	0.0347 (9)
C29	0.7387 (4)	−0.0260 (2)	0.3724 (3)	0.0402 (9)
O1	0.7541 (3)	−0.09167 (16)	0.3471 (2)	0.0555 (8)
O2	0.7516 (3)	−0.00923 (15)	0.4837 (2)	0.0530 (8)
C30	0.7334 (4)	0.0698 (2)	0.4990 (3)	0.0432 (10)
O3	0.7406 (3)	0.09324 (17)	0.5901 (2)	0.0618 (8)
H3	0.489 (4)	−0.061 (2)	0.269 (3)	0.058 (11)*
H4	0.277 (4)	−0.059 (2)	0.118 (3)	0.044 (10)*
H5	0.233 (4)	0.037 (2)	−0.027 (3)	0.072 (13)*
H6	0.403 (4)	0.136 (2)	−0.020 (3)	0.058 (12)*
H8	0.628 (3)	0.1869 (19)	0.055 (3)	0.039 (9)*
H10	0.860 (3)	0.171 (2)	0.045 (3)	0.036 (10)*
H11	1.075 (4)	0.110 (2)	0.098 (3)	0.042 (10)*
H12	1.128 (4)	0.013 (2)	0.240 (3)	0.053 (11)*
H13	0.970 (3)	−0.018 (2)	0.336 (3)	0.043 (10)*
H17	0.486 (3)	0.102 (2)	0.469 (3)	0.042 (11)*
H18	0.267 (4)	0.168 (2)	0.408 (3)	0.064 (13)*
H19	0.224 (4)	0.262 (2)	0.270 (3)	0.053 (11)*
H20	0.400 (4)	0.287 (2)	0.188 (3)	0.052 (12)*
H22	0.630 (3)	0.2774 (18)	0.176 (2)	0.024 (8)*
H24	0.865 (3)	0.3279 (19)	0.246 (3)	0.034 (9)*
H25	1.087 (4)	0.328 (2)	0.388 (3)	0.068 (13)*
H26	1.132 (5)	0.227 (3)	0.532 (4)	0.083 (15)*
H27	0.969 (4)	0.137 (2)	0.537 (3)	0.050 (11)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.033 (2)	0.029 (2)	0.0329 (19)	0.0027 (17)	0.0069 (16)	−0.0002 (16)
C2	0.035 (2)	0.035 (2)	0.040 (2)	−0.0014 (18)	0.0118 (17)	−0.0042 (18)
C3	0.036 (2)	0.042 (2)	0.045 (2)	−0.005 (2)	0.010 (2)	−0.001 (2)
C4	0.037 (2)	0.056 (3)	0.056 (3)	−0.011 (2)	0.014 (2)	−0.016 (2)
C5	0.033 (2)	0.063 (3)	0.046 (3)	0.003 (2)	0.003 (2)	−0.013 (2)
C6	0.038 (2)	0.052 (3)	0.036 (2)	0.008 (2)	0.0046 (19)	−0.003 (2)
C7	0.030 (2)	0.037 (2)	0.0347 (19)	0.0054 (17)	0.0061 (17)	−0.0013 (18)
C8	0.037 (2)	0.044 (2)	0.031 (2)	0.006 (2)	0.0063 (17)	0.0095 (19)
C9	0.032 (2)	0.036 (2)	0.0308 (19)	−0.0018 (18)	0.0073 (17)	−0.0039 (17)
C10	0.037 (2)	0.048 (2)	0.042 (2)	−0.003 (2)	0.0141 (19)	0.002 (2)
C11	0.043 (3)	0.064 (3)	0.063 (3)	0.003 (2)	0.029 (2)	0.004 (3)
C12	0.040 (3)	0.058 (3)	0.065 (3)	0.013 (2)	0.018 (2)	0.010 (2)
C13	0.037 (2)	0.042 (2)	0.045 (2)	0.004 (2)	0.009 (2)	0.005 (2)
C14	0.030 (2)	0.034 (2)	0.0366 (19)	−0.0002 (18)	0.0085 (17)	−0.0027 (18)
C15	0.033 (2)	0.032 (2)	0.034 (2)	0.0025 (18)	0.0075 (16)	0.0015 (17)
C16	0.034 (2)	0.036 (2)	0.0338 (19)	−0.0004 (18)	0.0088 (17)	−0.0032 (18)
C17	0.049 (3)	0.053 (3)	0.045 (2)	0.004 (2)	0.020 (2)	0.003 (2)
C18	0.045 (3)	0.070 (3)	0.071 (3)	0.006 (3)	0.030 (3)	−0.001 (3)
C19	0.036 (3)	0.058 (3)	0.072 (3)	0.013 (2)	0.014 (2)	−0.001 (3)
C20	0.043 (3)	0.044 (2)	0.051 (3)	0.011 (2)	0.013 (2)	0.003 (2)
C21	0.032 (2)	0.034 (2)	0.041 (2)	0.0032 (18)	0.0106 (17)	−0.0042 (18)
C22	0.036 (2)	0.031 (2)	0.038 (2)	0.0022 (18)	0.0105 (18)	0.0070 (18)
C23	0.0310 (19)	0.031 (2)	0.040 (2)	0.0055 (18)	0.0094 (17)	0.0013 (17)
C24	0.047 (3)	0.037 (2)	0.048 (2)	−0.005 (2)	0.020 (2)	0.001 (2)
C25	0.041 (2)	0.050 (3)	0.059 (3)	−0.010 (2)	0.018 (2)	−0.020 (2)
C26	0.032 (2)	0.053 (3)	0.053 (3)	−0.002 (2)	0.008 (2)	−0.009 (2)
C27	0.036 (2)	0.038 (2)	0.045 (2)	0.006 (2)	0.005 (2)	−0.003 (2)
C28	0.032 (2)	0.034 (2)	0.037 (2)	0.0058 (18)	0.0083 (18)	−0.0065 (18)
C29	0.037 (2)	0.036 (2)	0.044 (2)	−0.0020 (19)	0.0074 (18)	0.004 (2)
O1	0.0603 (19)	0.0324 (16)	0.0663 (18)	0.0002 (14)	0.0091 (15)	0.0005 (14)
O2	0.0718 (19)	0.0407 (16)	0.0422 (17)	0.0045 (15)	0.0117 (14)	0.0127 (13)
C30	0.041 (2)	0.046 (2)	0.039 (2)	0.001 (2)	0.0067 (18)	0.004 (2)
O3	0.084 (2)	0.0652 (19)	0.0329 (15)	0.0045 (17)	0.0136 (15)	0.0020 (15)

Geometric parameters (Å, º)

C1—C29	1.510 (5)	C15—C28	1.522 (5)
C1—C14	1.535 (5)	C15—C16	1.531 (5)
C1—C2	1.539 (5)	C16—C17	1.386 (5)
C1—C15	1.614 (5)	C16—C21	1.398 (5)
C2—C3	1.382 (5)	C17—C18	1.373 (6)
C2—C7	1.400 (5)	C17—H17	0.95 (3)
C3—C4	1.401 (5)	C18—C19	1.379 (6)
C3—H3	1.05 (4)	C18—H18	0.95 (4)
C4—C5	1.375 (6)	C19—C20	1.383 (6)
C4—H4	0.96 (4)	C19—H19	0.98 (4)
C5—C6	1.374 (6)	C20—C21	1.385 (5)
C5—H5	0.98 (4)	C20—H20	0.91 (4)
C6—C7	1.389 (5)	C21—C22	1.512 (5)
C6—H6	1.00 (4)	C22—C23	1.516 (5)
C7—C8	1.510 (5)	C22—H22	1.03 (3)
C8—C9	1.508 (5)	C23—C24	1.385 (5)
C8—C22	1.612 (5)	C23—C28	1.408 (5)
C8—H8	1.03 (3)	C24—C25	1.392 (5)
C9—C10	1.391 (5)	C24—H24	1.04 (3)
C9—C14	1.408 (5)	C25—C26	1.384 (6)
C10—C11	1.382 (5)	C25—H25	1.01 (4)
C10—H10	0.95 (3)	C26—C27	1.382 (5)
C11—C12	1.369 (6)	C26—H26	0.93 (4)
C11—H11	0.96 (3)	C27—C28	1.384 (5)
C12—C13	1.384 (5)	C27—H27	0.95 (4)
C12—H12	0.97 (4)	C29—O1	1.187 (4)
C13—C14	1.376 (5)	C29—O2	1.391 (4)
C13—H13	1.01 (3)	O2—C30	1.381 (5)
C15—C30	1.515 (5)	C30—O3	1.192 (4)
C29—C1—C14	110.4 (3)	C28—C15—C1	111.3 (3)
C29—C1—C2	110.7 (3)	C16—C15—C1	112.3 (3)
C14—C1—C2	108.4 (3)	C17—C16—C21	119.6 (3)
C29—C1—C15	103.0 (3)	C17—C16—C15	125.0 (3)
C14—C1—C15	112.8 (3)	C21—C16—C15	115.3 (3)
C2—C1—C15	111.5 (3)	C18—C17—C16	120.6 (4)
C3—C2—C7	120.4 (3)	C18—C17—H17	122 (2)
C3—C2—C1	124.0 (3)	C16—C17—H17	117 (2)
C7—C2—C1	115.6 (3)	C17—C18—C19	120.3 (4)
C2—C3—C4	119.6 (4)	C17—C18—H18	122 (2)
C2—C3—H3	122 (2)	C19—C18—H18	117 (2)
C4—C3—H3	119 (2)	C18—C19—C20	119.6 (4)
C5—C4—C3	119.8 (4)	C18—C19—H19	120 (2)
C5—C4—H4	120 (2)	C20—C19—H19	121 (2)
C3—C4—H4	120 (2)	C19—C20—C21	120.9 (4)
C6—C5—C4	120.6 (4)	C19—C20—H20	122 (2)
C6—C5—H5	118 (2)	C21—C20—H20	117 (2)
C4—C5—H5	122 (2)	C20—C21—C16	119.0 (4)
C5—C6—C7	120.7 (4)	C20—C21—C22	122.9 (3)
C5—C6—H6	125 (2)	C16—C21—C22	118.1 (3)
C7—C6—H6	115 (2)	C21—C22—C23	108.4 (3)
C6—C7—C2	118.9 (4)	C21—C22—C8	111.4 (3)
C6—C7—C8	123.3 (3)	C23—C22—C8	112.1 (3)
C2—C7—C8	117.9 (3)	C21—C22—H22	109.3 (16)
C9—C8—C7	108.0 (3)	C23—C22—H22	109.9 (16)
C9—C8—C22	111.4 (3)	C8—C22—H22	105.7 (15)
C7—C8—C22	112.8 (3)	C24—C23—C28	119.7 (3)
C9—C8—H8	110.1 (18)	C24—C23—C22	122.9 (3)
C7—C8—H8	109.5 (18)	C28—C23—C22	117.4 (3)
C22—C8—H8	105.1 (18)	C23—C24—C25	120.4 (4)
C10—C9—C14	118.7 (3)	C23—C24—H24	118.4 (17)
C10—C9—C8	123.2 (3)	C25—C24—H24	121.2 (17)
C14—C9—C8	118.1 (3)	C26—C25—C24	119.7 (4)
C11—C10—C9	120.0 (4)	C26—C25—H25	123 (2)
C11—C10—H10	123 (2)	C24—C25—H25	117 (2)
C9—C10—H10	117 (2)	C27—C26—C25	120.1 (4)
C12—C11—C10	120.8 (4)	C27—C26—H26	117 (3)
C12—C11—H11	123 (2)	C25—C26—H26	123 (3)
C10—C11—H11	117 (2)	C26—C27—C28	121.0 (4)
C11—C12—C13	120.3 (4)	C26—C27—H27	119 (2)
C11—C12—H12	120 (2)	C28—C27—H27	120 (2)
C13—C12—H12	120 (2)	C27—C28—C23	119.1 (4)
C14—C13—C12	119.7 (4)	C27—C28—C15	125.1 (3)
C14—C13—H13	121 (2)	C23—C28—C15	115.7 (3)
C12—C13—H13	119 (2)	O1—C29—O2	118.9 (3)
C13—C14—C9	120.6 (3)	O1—C29—C1	129.8 (4)
C13—C14—C1	124.3 (3)	O2—C29—C1	111.3 (3)
C9—C14—C1	115.1 (3)	C30—O2—C29	111.4 (3)
C30—C15—C28	111.0 (3)	O3—C30—O2	119.3 (3)
C30—C15—C16	109.8 (3)	O3—C30—C15	129.2 (4)
C28—C15—C16	109.4 (3)	O2—C30—C15	111.5 (3)
C30—C15—C1	102.8 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C24—H24···O3^i	1.04 (3)	2.38 (3)	3.386 (5)	162 (2)

Symmetry code: (i) x, −y+1/2, z−1/2.