6,6′-Di­chloro-3,3′-(butane-1,4-diyl­dioxy)­diflavone

Molecules of the title compound, C₃₄H₂₄Cl₂O₆, lie across crystallographic inversion centres. The flavone moiety is slightly folded, with the benzene and di­hydro­pyrone rings making a dihedral angle of 2.5 (2)°. In the crystal, the mol­ecules exist as cyclic intermolecular C—H...Cl hydrogen-bonded dimers. The structure is further stabilized by van der Waals interactions.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.011 Å
• R factor = 0.056
• wR factor = 0.159
• Data-to-parameter ratio = 10.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level B:



THETM_01  Alert B The value of sine(theta_max)/wavelength is less than 0.575
          Calculated sin(theta_max)/wavelength =    0.5651

Author response: see _publ_section_exptl_refinement

 Alert Level C:



RINTA_01  Alert C The value of Rint is greater than 0.10
          Rint given   0.122


 0 Alert Level A = Potentially serious problem

 1 Alert Level B = Potential problem

 1 Alert Level C = Please check

---

S1. Comment

Benzopyran derivatives are anti-inflammatory and anti-allergic, and are used to treat elephantiasis. These compounds are capable of inducing alteration in DNA structure and replication. Flavonoids exhibit antidiabetic (Hii & Howell, 1985; Basnet et al., 1993; Ragunathan & Sulochana, 1994) and aldose reductase inhibitory activities (Varma & Kinoshita, 1976; Okuda et al., 1984; Aida et al., 1990). Chromanone compounds are used to treat angina pectoris (Hasegaida, 1967) and these compounds show vasodilating activity on the coronary vascular bed (Nagao et al., 1972). Diethyl 2,6-dimethyl-4-(2-phenyl-4-oxo-4H-1-benzopyran-6-yl)-1,4-dihydropyridine- 3,5-dicarboxylate, containing a 2-phenyl-4H-benzopyran-4-one (flavone) is known to have a coronary dilatory effect (Itz & Potzsch, 1963) and capillary resistance activity (Gabor, 1981).

The asymmetric unit of the title compound, (I), consists of one-half of the molecule, with the other half generated by a crystallographic inversion centre at (1 − x, 1 − y, 1 − z). The geometry of the benzopyran moiety is comparable with those observed in related structures (Thinagar et al., 2000; Bruno et al., 2001; Ozbey et al., 1999). The bond angles around C2 of the heterocyclic ring vary from 113.1 (7) to 123.6 (7)°, indicating significant deviation from the ideal value. The O2—C9—C10—C15 torsion angle [141.8 (7)°] shows a +anticlinal conformation of the phenyl ring with respect to the flavone moiety. The O3—C16 bond is in a trans orientation with respect to the flavone moiety, which is evidenced by the C1—O3—C16—C17 torsion angle of 172.4 (6)°. The pyran ring is planar within ±0.032 (8) Å, compared to the usual half-chair conformation (Alex et al. 1993). However, the flavone moiety is not strictly planar, as the benzene and dihydropyrone rings form a dihedral angle of 2.2 (3)°. The O atom of the keto group deviates from the flavone moiety by −0.084 (5). The dihedral angle between the planes of the flavone moiety and the phenyl ring is 42.5 (3)°.

The molecular structure of (I) is stabilized by intramolecular C—H···O hydrogen bonds and the crystal packing is stabilized by C—H···Cl intermolecular hydrogen bonds (Table 2). The intramolecular C16—H16A···O1 hydrogen bond is involved in R₁¹(5) ring formation. In the crystal, an intermolecular C4—H4···Cl(-x, 1 − y, −z) hydrogen bond is involved in cyclic dimer formation, with an R₂²(8) ring descriptor (Bernstein et al., 1995).

S2. Experimental

A suspension of 6-chloro-3-hydroxy-2-(2-furyl)-4-oxo-4H-1-benzopyran (1 g, 0.0038 mol), 1,4-dibromobutane (0.0019 mol), tetra-n-butylammonium iodide (1 g) and freshly ignited K₂Co₃ (1 g) were refluxed in dry acetone (30 ml) for 4 h. The colour of the reaction mixture changed from yellow to colourless. The reaction mixture, after filtration and distillation of acetone, was poured into cold water to obtain a mixture of the monochromone and bischromone. This was then crystallized from acetone to obtain pure bischromone.

S3. Refinement

All H atoms were fixed geometrically and allowed to ride on the corresponding non-H atoms, with C—H distances of 0.93 or 0.97 Å, and U_iso(H) = 1.2U_eq(C). The large R_int value (0.122) and low ratio of observed to unique reflections (1/3), are a result of the poor diffraction quality of the crystal. The intensity data collection was restricted to θ_max of 23.68°, as the reflections were found to be rather weak at higher angles.

Computing details

Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 1990); software used to prepare material for publication: SHELXL97 and PARST (Nardelli, 1995).

Figures

Fig. 1. A view of the title molecule, showing 40% probability displacement ellipsoids and the atom-numbering scheme. Only the contents of the asymmetric unit are numbered.

6,6'-Dichloro-3,3'-(butane-1,4-diyldioxy)diflavone

Crystal data

C34H24Cl2O6	Z = 1
Mr = 599.43	F(000) = 310
Triclinic, P1	Dx = 1.460 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 5.335 (9) Å	Cell parameters from 25 reflections
b = 9.242 (8) Å	θ = 2–22°
c = 13.969 (9) Å	µ = 0.29 mm^−1
α = 89.27 (1)°	T = 293 K
β = 82.68 (1)°	Block, colourless
γ = 86.47 (1)°	0.30 × 0.29 × 0.27 mm
V = 681.8 (14) Å^3

Data collection

Enraf-Nonius CAD-4 diffractometer	Rint = 0.122
Radiation source: fine-focus sealed tube	θmax = 23.7°, θmin = 2.7°
Graphite monochromator	h = −6→0
Non–profiled w/2θ scans	k = −10→10
2312 measured reflections	l = −15→15
2056 independent reflections	3 standard reflections every 100 reflections
685 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)] = 0.056	H-atom parameters constrained
wR(F^2) = 0.159	w = 1/[σ^2(Fo^2) + (0.0553P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.91	(Δ/σ)max < 0.001
2056 reflections	Δρmax = 0.29 e Å^−3
191 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: 0.018 (4)

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
Cl1	0.1694 (4)	0.3740 (2)	−0.13199 (14)	0.0600 (8)
O1	0.2970 (10)	0.4448 (6)	0.2383 (3)	0.0561 (17)
O2	0.8111 (10)	0.1188 (5)	0.1416 (3)	0.0483 (14)
O3	0.6268 (9)	0.3219 (5)	0.3616 (3)	0.0426 (14)
C1	0.6415 (15)	0.2821 (8)	0.2677 (5)	0.041 (2)
C2	0.4600 (14)	0.3528 (8)	0.2076 (5)	0.041 (2)
C3	0.4871 (14)	0.2954 (7)	0.1094 (5)	0.035 (2)
C4	0.3335 (15)	0.3517 (8)	0.0416 (5)	0.049 (2)
H4	0.2096	0.4247	0.0599	0.059*
C5	0.3626 (14)	0.3015 (8)	−0.0498 (5)	0.042 (2)
C6	0.5444 (14)	0.1923 (8)	−0.0786 (5)	0.047 (2)
H6	0.5648	0.1596	−0.1420	0.057*
C7	0.6934 (14)	0.1326 (8)	−0.0147 (5)	0.048 (2)
H7	0.8134	0.0575	−0.0331	0.058*
C8	0.6621 (15)	0.1862 (8)	0.0785 (5)	0.045 (2)
C9	0.8047 (14)	0.1687 (8)	0.2353 (5)	0.039 (2)
C10	0.9624 (13)	0.0765 (8)	0.2910 (4)	0.035 (2)
C11	0.9814 (16)	−0.0723 (8)	0.2778 (5)	0.060 (3)
H11	0.8893	−0.1111	0.2332	0.072*
C12	1.1281 (16)	−0.1643 (9)	0.3270 (6)	0.066 (3)
H12	1.1337	−0.2639	0.3175	0.079*
C13	1.2698 (16)	−0.1045 (9)	0.3920 (6)	0.060 (2)
H13	1.3748	−0.1645	0.4257	0.072*
C14	1.2551 (16)	0.0400 (10)	0.4064 (6)	0.065 (3)
H14	1.3487	0.0786	0.4507	0.078*
C15	1.1043 (14)	0.1310 (8)	0.3566 (5)	0.048 (2)
H15	1.0976	0.2304	0.3672	0.058*
C16	0.7018 (15)	0.4696 (8)	0.3761 (4)	0.049 (2)
H16A	0.6097	0.5384	0.3385	0.058*
H16B	0.8816	0.4759	0.3558	0.058*
C17	0.6415 (12)	0.5022 (8)	0.4805 (4)	0.042 (2)
H17A	0.6967	0.5977	0.4921	0.051*
H17B	0.7372	0.4328	0.5164	0.051*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0686 (18)	0.0651 (16)	0.0508 (14)	−0.0001 (13)	−0.0262 (12)	−0.0019 (11)
O1	0.058 (4)	0.063 (4)	0.044 (3)	0.024 (3)	−0.005 (3)	−0.018 (3)
O2	0.054 (4)	0.056 (3)	0.033 (3)	0.021 (3)	−0.007 (3)	−0.015 (3)
O3	0.058 (4)	0.038 (3)	0.031 (3)	0.004 (3)	−0.004 (3)	−0.011 (2)
C1	0.057 (6)	0.044 (5)	0.023 (4)	−0.005 (5)	−0.007 (4)	−0.005 (4)
C2	0.041 (6)	0.041 (5)	0.041 (5)	0.000 (5)	−0.002 (4)	−0.009 (4)
C3	0.047 (6)	0.028 (5)	0.030 (4)	0.003 (4)	−0.006 (4)	−0.005 (4)
C4	0.058 (6)	0.038 (5)	0.051 (5)	0.003 (5)	−0.005 (5)	0.001 (4)
C5	0.056 (7)	0.046 (5)	0.026 (5)	−0.002 (5)	−0.015 (4)	0.001 (4)
C6	0.051 (6)	0.056 (6)	0.033 (4)	0.005 (5)	−0.003 (5)	−0.012 (4)
C7	0.043 (6)	0.063 (6)	0.039 (5)	0.012 (5)	−0.010 (4)	−0.018 (4)
C8	0.047 (6)	0.051 (6)	0.038 (5)	0.011 (5)	−0.011 (4)	−0.005 (4)
C9	0.049 (6)	0.038 (5)	0.031 (4)	0.010 (4)	−0.010 (4)	−0.021 (4)
C10	0.031 (5)	0.048 (5)	0.025 (4)	0.008 (4)	−0.005 (4)	−0.002 (4)
C11	0.088 (7)	0.050 (6)	0.043 (5)	0.021 (5)	−0.025 (5)	−0.021 (4)
C12	0.080 (7)	0.049 (6)	0.073 (6)	0.009 (5)	−0.037 (6)	−0.005 (5)
C13	0.064 (7)	0.055 (6)	0.063 (6)	0.007 (5)	−0.019 (5)	0.016 (5)
C14	0.083 (7)	0.058 (6)	0.061 (6)	0.010 (6)	−0.045 (5)	0.007 (5)
C15	0.062 (6)	0.037 (5)	0.047 (5)	−0.004 (5)	−0.013 (5)	−0.004 (4)
C16	0.058 (6)	0.047 (6)	0.038 (5)	−0.011 (5)	0.006 (4)	−0.009 (4)
C17	0.063 (6)	0.038 (5)	0.025 (4)	0.012 (5)	−0.007 (4)	−0.007 (3)

Geometric parameters (Å, º)

Cl1—C5	1.740 (7)	C9—C10	1.450 (9)
O1—C2	1.220 (7)	C10—C15	1.379 (8)
O2—C8	1.378 (7)	C10—C11	1.385 (9)
O2—C9	1.388 (7)	C11—C12	1.359 (9)
O3—C1	1.358 (7)	C11—H11	0.93
O3—C16	1.470 (7)	C12—C13	1.393 (9)
C1—C9	1.365 (8)	C12—H12	0.93
C1—C2	1.478 (9)	C13—C14	1.350 (9)
C2—C3	1.464 (8)	C13—H13	0.93
C3—C8	1.367 (9)	C14—C15	1.372 (9)
C3—C4	1.405 (8)	C14—H14	0.93
C4—C5	1.351 (9)	C15—H15	0.93
C4—H4	0.93	C16—C17	1.484 (8)
C5—C6	1.382 (9)	C16—H16A	0.97
C6—C7	1.359 (8)	C16—H16B	0.97
C6—H6	0.93	C17—C17^i	1.541 (13)
C7—C8	1.386 (8)	C17—H17A	0.97
C7—H7	0.93	C17—H17B	0.97
C8—O2—C9	121.0 (6)	C15—C10—C9	122.6 (7)
C1—O3—C16	114.4 (5)	C11—C10—C9	120.3 (7)
O3—C1—C9	118.8 (6)	C12—C11—C10	123.2 (7)
O3—C1—C2	118.5 (7)	C12—C11—H11	118.4
C9—C1—C2	122.4 (6)	C10—C11—H11	118.4
O1—C2—C3	123.6 (7)	C11—C12—C13	117.9 (8)
O1—C2—C1	123.2 (7)	C11—C12—H12	121.1
C3—C2—C1	113.1 (7)	C13—C12—H12	121.1
C8—C3—C4	116.6 (7)	C14—C13—C12	120.3 (8)
C8—C3—C2	122.4 (7)	C14—C13—H13	119.9
C4—C3—C2	121.0 (7)	C12—C13—H13	119.9
C5—C4—C3	121.1 (7)	C13—C14—C15	121.0 (8)
C5—C4—H4	119.4	C13—C14—H14	119.5
C3—C4—H4	119.4	C15—C14—H14	119.5
C4—C5—C6	120.5 (7)	C14—C15—C10	120.7 (7)
C4—C5—Cl1	119.9 (6)	C14—C15—H15	119.7
C6—C5—Cl1	119.6 (6)	C10—C15—H15	119.7
C7—C6—C5	120.3 (7)	O3—C16—C17	107.3 (5)
C7—C6—H6	119.9	O3—C16—H16A	110.2
C5—C6—H6	119.9	C17—C16—H16A	110.2
C6—C7—C8	118.4 (8)	O3—C16—H16B	110.2
C6—C7—H7	120.8	C17—C16—H16B	110.2
C8—C7—H7	120.8	H16A—C16—H16B	108.5
C3—C8—O2	120.6 (7)	C16—C17—C17^i	114.3 (7)
C3—C8—C7	123.1 (7)	C16—C17—H17A	108.7
O2—C8—C7	116.3 (7)	C17^i—C17—H17A	108.7
C1—C9—O2	120.2 (6)	C16—C17—H17B	108.7
C1—C9—C10	127.5 (6)	C17^i—C17—H17B	108.7
O2—C9—C10	111.9 (6)	H17A—C17—H17B	107.6
C15—C10—C11	117.0 (7)
C16—O3—C1—C9	117.5 (7)	C6—C7—C8—C3	0.6 (12)
C16—O3—C1—C2	−69.2 (8)	C6—C7—C8—O2	177.8 (7)
O3—C1—C2—O1	−0.2 (11)	O3—C1—C9—O2	175.4 (6)
C9—C1—C2—O1	172.8 (8)	C2—C1—C9—O2	2.4 (11)
O3—C1—C2—C3	−177.1 (6)	O3—C1—C9—C10	3.3 (12)
C9—C1—C2—C3	−4.1 (10)	C2—C1—C9—C10	−169.7 (7)
O1—C2—C3—C8	−176.1 (8)	C8—O2—C9—C1	2.8 (10)
C1—C2—C3—C8	0.8 (10)	C8—O2—C9—C10	176.1 (7)
O1—C2—C3—C4	4.4 (12)	C1—C9—C10—C15	−45.6 (12)
C1—C2—C3—C4	−178.7 (7)	O2—C9—C10—C15	141.8 (7)
C8—C3—C4—C5	−1.3 (11)	C1—C9—C10—C11	136.3 (8)
C2—C3—C4—C5	178.3 (7)	O2—C9—C10—C11	−36.3 (10)
C3—C4—C5—C6	0.4 (11)	C15—C10—C11—C12	1.0 (12)
C3—C4—C5—Cl1	−179.9 (6)	C9—C10—C11—C12	179.2 (8)
C4—C5—C6—C7	1.1 (12)	C10—C11—C12—C13	−1.5 (13)
Cl1—C5—C6—C7	−178.7 (6)	C11—C12—C13—C14	1.4 (13)
C5—C6—C7—C8	−1.5 (12)	C12—C13—C14—C15	−0.9 (14)
C4—C3—C8—O2	−176.3 (7)	C13—C14—C15—C10	0.4 (13)
C2—C3—C8—O2	4.2 (11)	C11—C10—C15—C14	−0.4 (11)
C4—C3—C8—C7	0.8 (11)	C9—C10—C15—C14	−178.6 (8)
C2—C3—C8—C7	−178.7 (7)	C1—O3—C16—C17	172.4 (6)
C9—O2—C8—C3	−6.1 (11)	O3—C16—C17—C17^i	−61.0 (10)
C9—O2—C8—C7	176.6 (6)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C16—H16A···O1	0.97	2.51	3.091 (10)	118
C4—H4···Cl1^ii	0.93	2.76	3.688 (10)	174

Symmetry code: (ii) −x, −y+1, −z.