Weak inter­molecular inter­actions in isomorphous 5-(2-chloro­ethoxy)-2,3-dihydro-1,4-benzodioxine and 5-(2-bromo­ethoxy)-2,3-dihydro-1,4-benzodioxine: bonding or nonbonding inter­actions

The title compounds, C₁₀H₁₁ClO₃, (I), and C₁₀H₁₁BrO₃, (II), are isomorphous and effectively isostructural; all of the inter­atomic distances and angles are normal. The structures exhibit long inter­molecular C—H...O and C—H...π contacts with attractive energies ranging from 1.17 to 2.30 kJ mol⁻¹. Weak C—H...O hydrogen bonds form C(3) and C(4) motifs, combining to form a two-dimensional R₃⁴(12) net. No face-to-face stacking inter­actions are observed.

S1. Comment

Hydrogen bonding is a phenomenon crucial in chemical, catalytic and biochemical processes, chemical and crystal engineering, and supramolecular chemistry (Jeffrey & Saenger, 1991; Jeffrey, 1997; Epstein & Shubina, 2002). Nowadays much attention is focused on the nature and properties of weak hydrogen bonds because they strongly influence the behaviour of many organic molecules and biomolecules (Szatyłowicz, 2008).

5-(2-Chloroethoxy)-2,3-dihydro-1,4-benzodioxine, (I), is an important compound used in the synthesis of second generation antidepressants responsible for 5-HT1A antagonism in serotonin reuptake inhibitors (Mewshaw et al., 2002, 2004). 5-(2-Bromoethoxy)-2,3-dihydro-1,4-benzodioxine, (II), is a reactant utilized in the synthesis of tetrahydroquinoline-based protein farnesyltransferase inhibitors used as antimalarials (Bendale et al., 2007). Compounds (I) and (II) are also excellent for the study of weak hydrogen bonding because they contain only weak C—H donors and weak O_(ether), π(arene) and halogen acceptors.

Compounds (I) and (II) (Figs. 1 and 2) are isomorphous and effectively isostructural: the molecules are conformationally chiral and the reference molecules have been selected to have the same configuration. On this basis the atomic coordinates for corresponding atoms in the two structures are approximately related by the transformation (-x + 1, y, -z + 3/2), although the values of the Flack x parameter (Flack, 1983) indicate that both structures are correctly oriented. Thus the crystal structures of (I) and (II) are related by a twofold rotation about [010].

All the interatomic distances and angles in (I) and (II) are normal, and the typical shortening of the C_phenyl—O ether bonds (Tables 1 and 2) is observed [the mean value is 1.38 (2) Å for 27688 structures found in the Cambridge Structural Database (CSD; Version 5.29 + update 1; Allen, 2002)]. The 2-chloroethoxy and 2-bromoethoxy substituents are close to planarity (Table 1) and they are almost coplanar with the adjacent aryl rings [the dihedral angle between the corresponding least squares planes is 4.9 (3)° for (I) and 5.5 (3)° for (II)]. In both compounds, the conformation of the heteroatomic ring is an unsymmetrical half-chair, with a local pseudo-twofold axis across the midpoints of the C2—C3 and C7—C8 bonds. This is distorted toward the sofa conformation, with a pseudo-mirror plane perpendicular to the ring plane on the line C3···C7 (Duax & Norton, 1975; Duax et al., 1976). The values of the smallest asymmetry parameters are C₂(C1···C3, C7—C8) = 10.5 (3)° [should this be C2—C3?] [for both (I) and (II)] and C_s(C3···C7) = 13.5 (3) and 13.9 (2)° for (I) and (II), respectively. The values of the ring-puckering angles θ and ϕ (Cremer & Pople, 1975) for the atom sequence O2—C2—C3—O4—C8—C7 are, respectively, 130.1 (4) and 101.2 (4)° in (I), and 129.3 (3) and 101.2 (3)° in (II).

This ring conformation is relatively uncommon in comparison with the conformations of 129 2,3-dihydro-1,4-benzodioxine ring systems found in the CSD, where the O—C═C—O torsion angle has a mean absolute value of 2.0 (2)° and the O—C—C—O torsion-angle distribution can be divided into two distinct sets, one close to 60° and the second close to 0°: the mean absolute values of are 58.1 (8) and 4.3 (10)°, respectively. The C—C—O—C torsion angles are spread over wider range (Fig. 3), but again preferred values can be detected: 17.0 and 47.4°, respectively, for the C≐ C—O—C and C_phenyl—O—C—C torsion angles. In general, an increase in one angle is associated with an increase in the second (Fig. 3). In (I) and (II), the O—C—C—O torsion angles are close to typical values (Tables 1 and 2). The C—C—O—C torsion angles differ considerably from the preferred ones (Fig. 3), and only in four structures (Chekhlov et al., 1993; Donnelly et al., 1987; Kuipers et al., 1997; Nicolaou et al., 2004) are the torsion angles within 2° of those found for (I) and (II).

Each structure contains very long C—H···O and two C—H···π(arene) intermolecular interactions (Table 3), which could be considered as very weak hydrogen bonds (Desiraju & Steiner 1999). The C—H···O contacts generate C(3) and C(4) first-level graph motifs (Bernstein et al., 1995), along [100] and [101], respectively, and the resulting second-level graph motif is R₃⁴(12), giving a two-dimensional net parallel to (010). However, no face-to-face stacking interactions are observed in the structures of (I) and (II).

The molecular electronic properties have been calculated at a single point from the experimental coordinates as well as for optimized structures. The structural parameters were a starting model in each calculation. The optimized geometrical parameters were in good agreement with those found from X-ray measurements. although the geometrically optimized molecules typically show an elongation of the C—H, N—H and O—H bonds (from 0.07 to 0.16 Å). This effect leads to a slight narrowing of the D—H···A angle, but the D···A distance remains unchanged.

The intermolecular interactions were calculated for molecular sets containing from two to 13 molecules. The sets were constructed using a single molecule as the starting point and adding extra molecules one by one along intermolecular interactions in both hemispherical and linear modes. The first completed hemisphere contained the central molecule and four satellites at (x - 1, y, z), (x - 1/2, -y + 1/2, z - 1/2), (x + 1, y, z) and (x + 1/2, -y + 1/2, z + 1/2), and the second contained an additional eight satellites. In linear mode the sets were constructed along the hydrogen-bonded chain directions and they contained between two and ten molecules. Both restricted Hartree–Fock and density functional methods (B3LYP functional) in the triple zeta 6–311++G(3df,2p) basis set were used as implemented in GAUSSIAN03 (Frisch et al., 2004). In Table 3, the differences in electronic properties and energies originating from the different numbers of molecules used in the calculation and the differences between the various methods are given in parentheses as standard deviations. Where a deviation is given, the values were the same in their range of reported precision. The energies of the hydrogen bonds calculated in terms of natural bond orbital (NBO) energetic analysis (Foster & Weinhold, 1980; Reed & Weinhold, 1985; Reed et al., 1988) are collected in Table 3. The atomic and molecular properties were calculated at 298.15 K.

In general all hydrogen bonds in (I) and (II) must be considered as very weak. The second-order perturbation theory analysis of the Fock matrix in the NBO basis leads to the conclusion that the C—H···O interactions are formed mostly by hydrogen-bond-acceptor lone pairs donating electron density to the antibonding orbitals of D—H bonds, and these `delocalizations' energies are collected in Table 3. In these hydrogen bonds, the second most energetic interactions (but distinctly smaller than the above-mentioned first ones) are interactions between acceptor lone pairs and one-center Rydberg antibonding orbitals of H atoms (e.g. 0.46 kJ mol^-1 for the C8—H8B···O2ⁱ hydrogen bond; symmetry code as in Table 3). The C—H···π interactions are formed only by π-bonding orbitals of the aromatic ring donating electron density to the one-center Rydberg antibonding orbitals of H atoms. The principal 'delocalization' energies of these interactions are collected in Table 3. The energies of the intermolecular interactions, calculated on the basis of the total self-consistent field energy (E_SCF) [corrected for the basis set superposition error estimated by use of the counterpoise method (Boys & Bernardi, 1970)], are very close to the sum of the respective NBO total energies (E_{C8—H8B···O2}ⁱ + E_{C9—H9B···Cg}ⁱⁱⁱ and E_{C8—H8B···O4}ⁱⁱ + E_{C7—H7A···Cg}ⁱⁱ for (I); E_{C8—H8B···O2}ⁱⁱⁱ + E_{C9—H9B···Cg}ⁱ and E_{C8—H8B···O4}^iv + E_{C7—H7A···Cg}^iv for (II); symmetry codes as in Table 3 [see comment below regarding H7/H9A/B]). The differences are not larger than 0.04 kJ mol^-1, but in all cases E_SCF is slightly larger than the value obtained on the NBO basis as a result of the contributions of acceptors having occupied orbitals other than lone pairs (e.g. one-center Rydberg antibonding orbitals). In general, the strength of the C—H···O interactions decreases with the lengthening of the D···A distance (even if the D—H···A angle is larger). The C—H···π interactions depend distinctly less on the D···A distance than the C—H···O interactions, but a similar relationship is observed, especially for larger D—H···A angle.

Analysis of the NBO charges and those derived from the electrostatic properties using Breneman radii shows that H atoms involved in weak hydrogen bonds have a 0.16 (4) atomic units (a.u.) charge, O atoms have a -0.49 (6) a.u. charge and the aromatic ring C atoms have a total charge of -0.35 (9) a.u. divided almost equally among the six C atoms. It is noteworthy that in the case of calculations performed for a single molecule the correpsonding positive charges are about 0.02 a.u. larger and the negative charges are about 0.01 a.u. smaller. These values confirm that during the formation of weak intermolecular interactions some transfer of electron density occurs. The ab initio results show that the observed interactions are bonding in character, but they are very weak, with a total interaction energy gain during crystal formation of about 6.28 kJ mol^-1.

Related literature

For related literature, see: Allen (2002); Bernstein et al. (1995); Charton et al. (2000); Chekhlov et al. (1993); Cremer & Pople (1975); Daukshas et al. (1965); Desiraju & Steiner (1999); Donnelly et al. (1987); Duax & Norton (1975); Duax et al. (1976); Epstein & Shubina (2002); Foster & Weinhold (1980); Frisch et al. (2004); Jeffrey (1997); Jeffrey & Saenger (1991); Kuipers et al. (1997); Mewshaw et al. (2002, 2004); Nicolaou et al. (2004); Reed & Weinhold (1985); Reed et al. (1988); Spek (2009); Szatyłowicz (2008).

S2. Experimental

The syntheses of both (I) and (II) have been reproted previously (Daukshas et al., 1965; Mewshaw et al., 2002, 2004; Charton et al., 2000), but in all reported procedures, (I) was synthesized in a two-stage method via 5-hydroxy-2,3-dihydro-1,4-benzodioxine as the intermediate product. The procedure reported here is a one-pot synthesis giving the products with high yield and high purity. Commercially available 1,2,3-trihydroxybenzene (0.05 mol, 6.3055 g) was mixed with 0.10 mol of the appropriate 1,2-dihalogenoethane (7.90 ml of 1,2-dichloroethane or 8.64 ml of 1,2-dibromoethane), 8 ml of a 40% aqueous solution of NaOH and 1.0 g of tert-butylammonium bromide. The mixture was stirred vigorously for 20 h using a magnetic stirrer. The dark-brown reaction mixture was extracted four times with 10 ml of pentane. The combined extracts were washed with 10 ml of water and then evaporated to dryness under reduced pressure. The resulting products were recrystallized from laboratory ethanol (97%) [total yield 96.3% for (I) and 97.1% for (II)]. The yields of both compound can be increased to greater than 99.4% by increasing the reaction time to 7 d. Changing the molar ratio of the reactants (1,2,3-trihydroxybenzene:1,2-dihalogenoethane) in the range 1:1 to 1:3 leads to the formation of the same products with yields between 93.0 and 99.7% for a 20 h reaction.

S3. Refinement

All H atoms were treated as riding atoms with C—H distances 0.93 Å or 0.97 Å and with U_iso(H) set at 1.2U_eq(C)).

Computing details

For both compounds, data collection: CrysAlis CCD (UNIL IC & Kuma, 2000); cell refinement: CrysAlis RED (UNIL IC & Kuma, 2000); data reduction: CrysAlis RED (UNIL IC & Kuma, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL/PC (Sheldrick, 2008) and ORTEP-3 (Version 1.062; Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

	Fig. 1. The molecular structure of (I). Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radii.
	Fig. 2. The molecular structure of (II). Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as spheres of arbitrary radii.
	Fig. 3. Contour plot showing the relationship between C—O—C—C and C—O—C≐C torsion angle in 2,3-dihydro-1,4-benzodioxine ring systems. The values for (I) are indicated by star symbols.

(I) 5-(2-chloroethoxy)-2,3-dihydro-1,4-benzodioxine

Crystal data

C10H11ClO3	F(000) = 448
Mr = 214.64	Dx = 1.437 Mg m^−3 Dm = 1.44 Mg m^−3 Dm measured by Berman density torsion balance
Monoclinic, Cc	Melting point: 345.87 K
Hall symbol: C -2yc	Mo Kα radiation, λ = 0.71073 Å
a = 5.0961 (7) Å	Cell parameters from 4683 reflections
b = 25.0840 (19) Å	θ = 2–25°
c = 8.0217 (6) Å	µ = 0.36 mm^−1
β = 104.637 (8)°	T = 291 K
V = 992.14 (17) Å^3	Prism, colourless
Z = 4	0.28 × 0.27 × 0.24 mm

Data collection

Kuma KM-4 CCD diffractometer	1540 independent reflections
Radiation source: fine-focus sealed tube	1410 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.046
Detector resolution: 1048576 pixels mm^-1	θmax = 25.1°, θmin = 3.3°
ω scans	h = −6→4
Absorption correction: numerical (X-RED; Stoe & Cie, 1999)	k = −29→29
Tmin = 0.897, Tmax = 0.918	l = −9→9
5173 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.035	H-atom parameters constrained
wR(F^2) = 0.080	w = 1/[σ^2(Fo^2) + (0.0458P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max = 0.001
1540 reflections	Δρmax = 0.13 e Å^−3
127 parameters	Δρmin = −0.18 e Å^−3
2 restraints	Absolute structure: Flack (1983), 650 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.09 (7)

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	1.32635 (15)	0.04315 (3)	0.55933 (11)	0.0593 (2)
C1	0.7849 (5)	0.12367 (9)	0.9483 (3)	0.0377 (6)
C2	0.6323 (5)	0.16794 (10)	0.9726 (3)	0.0343 (6)
C3	0.5000 (5)	0.16727 (9)	1.1051 (3)	0.0379 (6)
C4	0.5272 (6)	0.12341 (11)	1.2154 (4)	0.0465 (7)
H4	0.4432	0.1233	1.3058	0.056*
C5	0.6793 (6)	0.08035 (11)	1.1893 (3)	0.0498 (8)
H5	0.6956	0.0510	1.2622	0.060*
C6	0.8089 (7)	0.07972 (9)	1.0568 (4)	0.0454 (6)
H6	0.9105	0.0503	1.0407	0.054*
O1	0.9032 (4)	0.12820 (6)	0.8123 (2)	0.0449 (5)
O2	0.6129 (4)	0.21047 (6)	0.8614 (2)	0.0412 (5)
O4	0.3469 (4)	0.20964 (7)	1.1351 (2)	0.0481 (5)
C7	0.5364 (7)	0.25883 (10)	0.9348 (4)	0.0450 (7)
H7A	0.4982	0.2866	0.8478	0.054*
H7B	0.6854	0.2707	1.0284	0.054*
C8	0.2920 (6)	0.24942 (11)	1.0008 (4)	0.0492 (7)
H8A	0.2386	0.2825	1.0456	0.059*
H8B	0.1430	0.2376	0.9070	0.059*
C9	1.0544 (6)	0.08326 (10)	0.7762 (4)	0.0427 (6)
H9A	0.9390	0.0520	0.7504	0.051*
H9B	1.2048	0.0754	0.8743	0.051*
C10	1.1562 (6)	0.09866 (10)	0.6233 (4)	0.0441 (7)
H10A	1.2801	0.1285	0.6527	0.053*
H10B	1.0054	0.1094	0.5291	0.053*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0630 (5)	0.0525 (4)	0.0709 (5)	0.0096 (4)	0.0327 (4)	−0.0064 (3)
C1	0.0293 (15)	0.0422 (14)	0.0437 (13)	0.0005 (12)	0.0131 (12)	−0.0022 (11)
C2	0.0324 (15)	0.0356 (12)	0.0354 (12)	−0.0030 (10)	0.0095 (11)	0.0011 (9)
C3	0.0311 (15)	0.0431 (14)	0.0402 (13)	−0.0079 (11)	0.0104 (12)	−0.0055 (11)
C4	0.0508 (18)	0.0541 (17)	0.0381 (13)	−0.0103 (14)	0.0179 (13)	0.0015 (12)
C5	0.055 (2)	0.0486 (17)	0.0447 (15)	−0.0102 (15)	0.0105 (15)	0.0086 (12)
C6	0.0413 (16)	0.0385 (12)	0.0548 (16)	0.0024 (13)	0.0094 (12)	0.0025 (14)
O1	0.0478 (12)	0.0389 (9)	0.0554 (11)	0.0086 (8)	0.0267 (9)	0.0037 (8)
O2	0.0453 (12)	0.0380 (9)	0.0463 (10)	0.0049 (8)	0.0225 (9)	0.0038 (8)
O4	0.0526 (13)	0.0494 (11)	0.0501 (10)	0.0019 (10)	0.0272 (10)	−0.0023 (9)
C7	0.0477 (18)	0.0390 (14)	0.0541 (17)	0.0089 (13)	0.0238 (14)	0.0020 (12)
C8	0.0469 (19)	0.0495 (15)	0.0559 (17)	0.0086 (14)	0.0220 (16)	0.0018 (12)
C9	0.0377 (16)	0.0391 (13)	0.0546 (16)	0.0046 (11)	0.0177 (14)	−0.0016 (11)
C10	0.0441 (17)	0.0415 (13)	0.0476 (15)	0.0072 (12)	0.0136 (13)	−0.0022 (12)

Geometric parameters (Å, º)

Cl1—C10	1.783 (3)	O1—C9	1.435 (3)
C1—O1	1.378 (3)	O2—C7	1.445 (3)
C1—C6	1.391 (3)	O4—C8	1.443 (3)
C1—C2	1.398 (3)	C7—C8	1.490 (4)
C2—O2	1.378 (3)	C7—H7A	0.9700
C2—C3	1.395 (4)	C7—H7B	0.9700
C3—O4	1.375 (3)	C8—H8A	0.9700
C3—C4	1.397 (4)	C8—H8B	0.9700
C4—C5	1.376 (4)	C9—C10	1.498 (4)
C4—H4	0.9300	C9—H9A	0.9700
C5—C6	1.386 (4)	C9—H9B	0.9700
C5—H5	0.9300	C10—H10A	0.9700
C6—H6	0.9300	C10—H10B	0.9700
O1—C1—C6	125.0 (2)	C8—C7—H7A	109.6
O1—C1—C2	114.5 (2)	O2—C7—H7B	109.6
C6—C1—C2	120.4 (2)	C8—C7—H7B	109.6
O2—C2—C3	122.2 (2)	H7A—C7—H7B	108.1
O2—C2—C1	118.4 (2)	O4—C8—C7	110.7 (2)
C3—C2—C1	119.4 (2)	O4—C8—H8A	109.5
O4—C3—C2	121.9 (2)	C7—C8—H8A	109.5
O4—C3—C4	117.9 (2)	O4—C8—H8B	109.5
C2—C3—C4	120.2 (2)	C7—C8—H8B	109.5
C5—C4—C3	119.4 (3)	H8A—C8—H8B	108.1
C5—C4—H4	120.3	O1—C9—C10	106.1 (2)
C3—C4—H4	120.3	O1—C9—H9A	110.5
C4—C5—C6	121.4 (2)	C10—C9—H9A	110.5
C4—C5—H5	119.3	O1—C9—H9B	110.5
C6—C5—H5	119.3	C10—C9—H9B	110.5
C5—C6—C1	119.2 (2)	H9A—C9—H9B	108.7
C5—C6—H6	120.4	C9—C10—Cl1	109.19 (17)
C1—C6—H6	120.4	C9—C10—H10A	109.8
C1—O1—C9	117.35 (18)	Cl1—C10—H10A	109.8
C2—O2—C7	111.62 (19)	C9—C10—H10B	109.8
C3—O4—C8	114.5 (2)	Cl1—C10—H10B	109.8
O2—C7—C8	110.3 (2)	H10A—C10—H10B	108.3
O2—C7—H7A	109.6
O2—C2—C3—O4	−1.5 (4)	C8—C7—O2—C2	−50.8 (3)
C2—C3—O4—C8	11.4 (3)	C7—O2—C2—C3	22.0 (3)
C3—O4—C8—C7	−40.4 (3)	C6—O1—C9—C10	−179.48 (19)
O4—C8—C7—O2	61.4 (3)	O1—C9—C10—Cl1	−175.80 (17)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8B···O2^i	0.97	2.72	3.497 (4)	138
C8—H8B···O4^ii	0.97	2.67	3.383 (4)	131
C7—H7A···Cg^ii	0.97	3.28	4.208 (6)	160
C9—H9B···Cg^iii	0.97	2.75	3.551 (6)	140

Symmetry codes: (i) x−1, y, z; (ii) x−1/2, −y+1/2, z−1/2; (iii) x+1, y, z.

(II) 5-(2-bromoethoxy)-2,3-dihydro-1,4-benzodioxine

Crystal data

C10H11BrO3	F(000) = 520
Mr = 259.10	Dx = 1.709 Mg m^−3 Dm = 1.71 Mg m^−3 Dm measured by Berman density torsion balance
Monoclinic, Cc	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C -2yc	Cell parameters from 5007 reflections
a = 5.0911 (8) Å	θ = 2–25°
b = 25.4143 (18) Å	µ = 4.06 mm^−1
c = 8.0469 (5) Å	T = 291 K
β = 104.690 (9)°	Prism, colourless
V = 1007.13 (18) Å^3	0.11 × 0.10 × 0.10 mm
Z = 4

Data collection

Kuma KM-4 CCD diffractometer	1746 independent reflections
Radiation source: fine-focus sealed tube	1712 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.020
Detector resolution: 1048576 pixels mm^-1	θmax = 25.0°, θmin = 3.1°
ω scans	h = −6→6
Absorption correction: numerical (X-RED; Stoe & Cie, 1999)	k = −30→30
Tmin = 0.640, Tmax = 0.677	l = −9→9
8036 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.018	H-atom parameters constrained
wR(F^2) = 0.048	w = 1/[σ^2(Fo^2) + (0.0171P)^2 + 0.3561P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max = 0.001
1746 reflections	Δρmax = 0.32 e Å^−3
127 parameters	Δρmin = −0.18 e Å^−3
2 restraints	Absolute structure: Flack (1983), 854 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.039 (8)

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
Br1	−0.32890 (6)	0.040575 (8)	0.94063 (5)	0.05341 (9)
C1	0.2191 (4)	0.12668 (9)	0.5506 (3)	0.0351 (5)
C2	0.3745 (4)	0.17023 (8)	0.5281 (3)	0.0320 (4)
C3	0.5042 (4)	0.16975 (9)	0.3957 (3)	0.0354 (5)
C4	0.4766 (5)	0.12684 (10)	0.2862 (3)	0.0435 (5)
H4	0.5624	0.1268	0.1970	0.052*
C5	0.3234 (5)	0.08469 (10)	0.3095 (3)	0.0456 (6)
H5	0.3058	0.0561	0.2354	0.055*
C6	0.1928 (7)	0.08371 (8)	0.4423 (4)	0.0420 (5)
H6	0.0900	0.0547	0.4577	0.050*
O1	0.1010 (3)	0.13095 (6)	0.6857 (2)	0.0431 (4)
O2	0.3940 (3)	0.21176 (6)	0.6394 (2)	0.0393 (4)
O4	0.6590 (3)	0.21135 (7)	0.3674 (2)	0.0461 (4)
C7	0.4706 (5)	0.25961 (10)	0.5676 (3)	0.0437 (5)
H7A	0.5100	0.2868	0.6550	0.052*
H7B	0.3215	0.2717	0.4747	0.052*
C8	0.7155 (5)	0.25002 (11)	0.5013 (3)	0.0482 (6)
H8A	0.7703	0.2826	0.4573	0.058*
H8B	0.8643	0.2380	0.5944	0.058*
C9	−0.0523 (5)	0.08669 (9)	0.7180 (3)	0.0383 (5)
H9A	0.0606	0.0554	0.7402	0.046*
H9B	−0.2050	0.0800	0.6203	0.046*
C10	−0.1491 (5)	0.10123 (9)	0.8731 (3)	0.0414 (5)
H10A	−0.2745	0.1306	0.8465	0.050*
H10B	0.0036	0.1116	0.9663	0.050*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.05798 (15)	0.04447 (13)	0.06478 (16)	−0.00657 (14)	0.02848 (11)	0.00791 (14)
C1	0.0307 (10)	0.0377 (11)	0.0373 (12)	0.0030 (8)	0.0095 (9)	0.0024 (9)
C2	0.0295 (10)	0.0332 (10)	0.0327 (10)	0.0047 (8)	0.0067 (8)	0.0010 (8)
C3	0.0327 (11)	0.0386 (12)	0.0354 (11)	0.0073 (9)	0.0098 (9)	0.0064 (9)
C4	0.0495 (14)	0.0487 (14)	0.0352 (12)	0.0094 (11)	0.0161 (10)	−0.0006 (10)
C5	0.0501 (14)	0.0464 (14)	0.0379 (12)	0.0078 (10)	0.0068 (11)	−0.0082 (10)
C6	0.0395 (12)	0.0374 (10)	0.0481 (11)	−0.0034 (12)	0.0090 (9)	−0.0029 (14)
O1	0.0479 (9)	0.0375 (8)	0.0507 (9)	−0.0091 (7)	0.0250 (8)	−0.0037 (7)
O2	0.0443 (9)	0.0358 (8)	0.0439 (9)	−0.0065 (6)	0.0225 (7)	−0.0036 (7)
O4	0.0515 (10)	0.0483 (10)	0.0459 (9)	−0.0028 (8)	0.0258 (8)	0.0026 (8)
C7	0.0474 (13)	0.0356 (12)	0.0535 (15)	−0.0052 (10)	0.0231 (11)	−0.0021 (10)
C8	0.0455 (14)	0.0502 (14)	0.0545 (15)	−0.0083 (11)	0.0231 (12)	0.0009 (11)
C9	0.0351 (11)	0.0335 (11)	0.0478 (13)	−0.0038 (8)	0.0133 (10)	0.0016 (9)
C10	0.0453 (12)	0.0365 (11)	0.0434 (12)	−0.0061 (10)	0.0129 (10)	0.0049 (10)

Geometric parameters (Å, º)

Br1—C10	1.939 (2)	O1—C9	1.430 (3)
C1—O1	1.374 (3)	O2—C7	1.442 (3)
C1—C6	1.382 (3)	O4—C8	1.432 (3)
C1—C2	1.399 (3)	C7—C8	1.496 (4)
C2—O2	1.372 (3)	C7—H7A	0.9700
C2—C3	1.388 (3)	C7—H7B	0.9700
C3—O4	1.372 (3)	C8—H8A	0.9700
C3—C4	1.387 (3)	C8—H8B	0.9700
C4—C5	1.366 (4)	C9—C10	1.500 (3)
C4—H4	0.9300	C9—H9A	0.9700
C5—C6	1.395 (4)	C9—H9B	0.9700
C5—H5	0.9300	C10—H10A	0.9700
C6—H6	0.9300	C10—H10B	0.9700
O1—C1—C6	124.7 (2)	C8—C7—H7A	109.7
O1—C1—C2	114.54 (18)	O2—C7—H7B	109.7
C6—C1—C2	120.8 (2)	C8—C7—H7B	109.7
O2—C2—C3	122.6 (2)	H7A—C7—H7B	108.2
O2—C2—C1	118.30 (19)	O4—C8—C7	110.7 (2)
C3—C2—C1	119.1 (2)	O4—C8—H8A	109.5
O4—C3—C4	118.1 (2)	C7—C8—H8A	109.5
O4—C3—C2	121.7 (2)	O4—C8—H8B	109.5
C4—C3—C2	120.2 (2)	C7—C8—H8B	109.5
C5—C4—C3	119.9 (2)	H8A—C8—H8B	108.1
C5—C4—H4	120.0	O1—C9—C10	105.50 (18)
C3—C4—H4	120.0	O1—C9—H9A	110.6
C4—C5—C6	121.3 (2)	C10—C9—H9A	110.6
C4—C5—H5	119.4	O1—C9—H9B	110.6
C6—C5—H5	119.4	C10—C9—H9B	110.6
C1—C6—C5	118.7 (2)	H9A—C9—H9B	108.8
C1—C6—H6	120.7	C9—C10—Br1	108.39 (16)
C5—C6—H6	120.7	C9—C10—H10A	110.0
C1—O1—C9	116.77 (17)	Br1—C10—H10A	110.0
C2—O2—C7	111.67 (17)	C9—C10—H10B	110.0
C3—O4—C8	114.72 (18)	Br1—C10—H10B	110.0
O2—C7—C8	109.9 (2)	H10A—C10—H10B	108.4
O2—C7—H7A	109.7
O2—C2—C3—O4	−0.6 (3)	C8—C7—O2—C2	−50.5 (3)
C2—C3—O4—C8	10.9 (3)	C7—O2—C2—C3	21.6 (3)
C3—O4—C8—C7	−40.3 (3)	C6—O1—C9—C10	179.28 (18)
O4—C8—C7—O2	61.4 (3)	O1—C9—C10—Br1	−174.32 (15)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8B···O2^i	0.97	2.71	3.488 (3)	137
C8—H8B···O4^ii	0.97	2.66	3.372 (3)	131
C7—H7A···Cg^ii	0.97	3.22	4.151 (5)	160
C9—H9B···Cg^iii	0.97	2.71	3.525 (5)	142

Symmetry codes: (i) x+1, y, z; (ii) x+1/2, −y+1/2, z+1/2; (iii) x−1, y, z.