Rerefinement of deca­bromo­di­phenyl ether from new area-detector data

Refinement of the title compound, bis(pentabromophenyl) ether, C₁₂Br₁₀O, from 100 K CCD data yields physically reasonable anisotropic displacement parameters for the C atoms. The C-Br distances are in the range 1.867 (4)-1.891 (4) Å and the dihedral angle formed by the phenyl rings is 78.3 (2)°. All endocyclic C-C-C angles are within 0.8 (4)° of the ideal value of 120°.

S1. Comment

Ericksson et al. (1999) recently reported the structure of the title flame-retardant compound, (I), at 100 K. They were unable to refine the C atoms with anisotropic displacement parameters, as some became non-positive definite. They observed an asymmetry in the O—C—C angles to both rings, as well as a spread of 117.3 (5)–122.0 (4)° among the endocyclic angles within phenyl ring C1–6, but no such asymmetry in phenyl ring C7–12. The asymmetry was attributed to intermolecular Br···Br contacts. \scheme

With serial diffractometer (CAD-4) data at both 100 and 150 K, we likewise experienced problems treating the C atoms of the title compound as anisotropic and observed that angles O1—C6—C5 and O1—C7—C12 were 5–10° larger than O1—C6—C1 and O1—C7—C8, but did not observe the asymmetric endocyclic bond angles. We have now refined the structure versus CCD data at 100 K, which yielded physically reasonable ellipsoids for the C atoms. Further, all endocyclic C—C—C angles are within 0.8° (2σ) of the ideal value of 120°. We do find the asymmetry in the O—C—C angles; however, it is also present in 1-bromo-4-(4-bromophenoxy)benzene (Mrse et al., 1998), and is thus unrelated to the perbromination of the title compound.

It is noteworthy that the smallest endocyclic C—C—C angle found by Ericksson et al. (1999) is at the C atom (C2) with the shortest C—Br distance, and likewise the largest C—C—C angle at a brominated site is at C3, which has the longest C—Br distance. This implies that the observed spread in C—C—C angles is likely a result of slightly misplaced C atoms, or of underestimation of the uncertainties in the C positions.

The cell dimensions of the title compound at 150 K are a = 8.3194 (8), b = 8.9602 (7), c = 14.3638 (11) Å, α = 80.368 (7), β = 84.494 (8), γ = 63.140 (8)°; V = 941.5 (2) ų; those at 297 K are a = 8.4295 (13), b = 9.0108 (6), c = 14.4141 (15) Å, α = 80.742 (11), β = 85.009 (14), γ = 62.848 (10)°; V = 961.4 (3) ų.

S2. Experimental

The title compound was kindly provided by the Albemarle Corporation. Single crystals were obtained by slow evaporation of a solution in dichlorobenzene.

S3. Refinement

The coordinates of Eriksson et al. (1999) were used as a beginning model, and were translated by x + 1/2 to avoid most negative values. The largest final difference peak is located 0.78 Å from Br7, and the deepest hole is located 0.55 Å from Br10.

Computing details

Data collection: COLLECT (Nonius, 1999); cell refinement: HKL SCALEPACK (Otwinowski & Minor 1997); data reduction: HKL DENZO and SCALEPACK (Otwinowski & Minor 1997); program(s) used to solve structure: coordinates of Eriksson, et al. (1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: SHELXL97.

1-(2,3,4,5,6-pentabromophenoxy)-2,3,4,5,6-pentabromobenzene

Crystal data

C12Br10O	Z = 2
Mr = 959.22	F(000) = 860
Triclinic, P1	Dx = 3.393 Mg m^−3
a = 8.3070 (5) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.9554 (4) Å	Cell parameters from 12388 reflections
c = 14.3472 (8) Å	θ = 2.5–40.2°
α = 80.407 (3)°	µ = 21.34 mm^−1
β = 84.441 (2)°	T = 100 K
γ = 63.194 (2)°	Prism, colourless
V = 938.97 (9) Å^3	0.10 × 0.07 × 0.05 mm

Data collection

KappaCCD (with Oxford Cryosystems Cryostream) diffractometer	10939 independent reflections
Radiation source: fine-focus sealed tube	4884 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.095
ω scans with κ offsets	θmax = 40.2°, θmin = 2.5°
Absorption correction: multi-scan (HKL SCALEPACK; Otwinowski & Minor, 1997)	h = 0→15
Tmin = 0.140, Tmax = 0.344	k = −14→15
12388 measured reflections	l = −25→26

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)] = 0.043	w = 1/[σ^2(Fo^2) + (0.0227P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.085	(Δ/σ)max = 0.001
S = 0.89	Δρmax = 2.01 e Å^−3
10939 reflections	Δρmin = −1.81 e Å^−3
209 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00156 (12)

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	0.70114 (6)	0.74656 (5)	0.88058 (3)	0.01772 (9)
Br2	0.90691 (5)	0.35246 (5)	0.98626 (3)	0.01858 (9)
Br3	0.74607 (6)	0.08410 (5)	0.96616 (3)	0.02085 (10)
Br4	0.37353 (6)	0.21657 (5)	0.84659 (3)	0.01930 (9)
Br5	0.17150 (5)	0.61547 (5)	0.74733 (3)	0.01869 (9)
Br6	0.06617 (5)	1.11730 (5)	0.73814 (3)	0.01969 (9)
Br7	−0.00995 (6)	1.25003 (5)	0.50871 (3)	0.02234 (10)
Br8	0.26459 (6)	1.01665 (5)	0.35239 (3)	0.02317 (10)
Br9	0.60866 (6)	0.65982 (5)	0.42398 (3)	0.02196 (10)
Br10	0.70628 (6)	0.55318 (5)	0.64704 (3)	0.02329 (10)
O1	0.3915 (4)	0.8062 (3)	0.7734 (2)	0.0168 (6)
C1	0.6122 (5)	0.5900 (5)	0.8735 (3)	0.0150 (8)
C2	0.6972 (5)	0.4243 (5)	0.9182 (3)	0.0128 (8)
C3	0.6286 (5)	0.3090 (5)	0.9081 (3)	0.0161 (8)
C4	0.4709 (5)	0.3641 (5)	0.8579 (3)	0.0126 (8)
C5	0.3856 (5)	0.5326 (5)	0.8134 (3)	0.0153 (8)
C6	0.4635 (5)	0.6418 (5)	0.8181 (3)	0.0135 (8)
C7	0.3686 (5)	0.8418 (5)	0.6759 (3)	0.0158 (8)
C8	0.2204 (5)	0.9927 (5)	0.6457 (3)	0.0155 (8)
C9	0.1900 (5)	1.0463 (5)	0.5494 (3)	0.0161 (9)
C10	0.3042 (5)	0.9479 (5)	0.4835 (3)	0.0151 (8)
C11	0.4541 (6)	0.7954 (5)	0.5137 (3)	0.0186 (9)
C12	0.4893 (5)	0.7451 (5)	0.6097 (3)	0.0161 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.01724 (19)	0.01479 (19)	0.0218 (2)	−0.00719 (16)	−0.00554 (17)	−0.00120 (16)
Br2	0.01143 (18)	0.01681 (19)	0.0246 (2)	−0.00290 (15)	−0.00845 (17)	−0.00064 (16)
Br3	0.0188 (2)	0.01202 (18)	0.0283 (2)	−0.00407 (16)	−0.00825 (18)	0.00226 (16)
Br4	0.0193 (2)	0.0201 (2)	0.0222 (2)	−0.01139 (17)	−0.00361 (18)	−0.00271 (17)
Br5	0.01160 (18)	0.0217 (2)	0.0206 (2)	−0.00444 (16)	−0.00613 (16)	−0.00275 (17)
Br6	0.01334 (19)	0.0182 (2)	0.0219 (2)	−0.00007 (15)	−0.00360 (17)	−0.00687 (16)
Br7	0.0159 (2)	0.0178 (2)	0.0245 (2)	0.00007 (16)	−0.00786 (18)	0.00182 (17)
Br8	0.0242 (2)	0.0259 (2)	0.0155 (2)	−0.00786 (18)	−0.00620 (18)	0.00104 (17)
Br9	0.0194 (2)	0.0228 (2)	0.0194 (2)	−0.00408 (17)	0.00020 (18)	−0.00775 (17)
Br10	0.0169 (2)	0.0206 (2)	0.0209 (2)	0.00194 (16)	−0.00173 (18)	−0.00304 (17)
O1	0.0190 (14)	0.0122 (13)	0.0152 (15)	−0.0022 (11)	−0.0049 (12)	−0.0032 (11)
C1	0.0138 (18)	0.0145 (18)	0.017 (2)	−0.0042 (15)	−0.0036 (16)	−0.0063 (15)
C2	0.0101 (17)	0.0154 (18)	0.0110 (18)	−0.0034 (15)	0.0025 (15)	−0.0056 (15)
C3	0.0168 (19)	0.0125 (18)	0.017 (2)	−0.0062 (16)	−0.0007 (17)	0.0035 (15)
C4	0.0107 (17)	0.0144 (18)	0.0106 (18)	−0.0040 (14)	−0.0001 (15)	−0.0011 (14)
C5	0.0118 (17)	0.0183 (19)	0.0120 (19)	−0.0044 (15)	−0.0041 (15)	0.0034 (15)
C6	0.0095 (17)	0.0132 (18)	0.013 (2)	−0.0008 (14)	0.0020 (15)	−0.0049 (15)
C7	0.0157 (19)	0.0176 (19)	0.015 (2)	−0.0076 (16)	−0.0037 (16)	−0.0023 (16)
C8	0.0091 (17)	0.0110 (17)	0.025 (2)	−0.0024 (14)	−0.0013 (16)	−0.0032 (16)
C9	0.0070 (17)	0.0153 (19)	0.026 (2)	−0.0047 (15)	−0.0042 (17)	−0.0019 (17)
C10	0.0171 (19)	0.0146 (19)	0.013 (2)	−0.0075 (16)	−0.0074 (16)	0.0047 (15)
C11	0.017 (2)	0.018 (2)	0.023 (2)	−0.0100 (17)	−0.0051 (18)	−0.0016 (17)
C12	0.0136 (18)	0.0160 (19)	0.016 (2)	−0.0040 (15)	−0.0066 (16)	−0.0001 (15)

Geometric parameters (Å, º)

Br1—C1	1.876 (4)	C1—C6	1.387 (5)
Br2—C2	1.874 (4)	C1—C2	1.392 (5)
Br3—C3	1.878 (4)	C2—C3	1.417 (5)
Br4—C4	1.867 (4)	C3—C4	1.400 (5)
Br5—C5	1.874 (4)	C4—C5	1.410 (5)
Br6—C8	1.876 (4)	C5—C6	1.408 (5)
Br7—C9	1.878 (4)	C7—C8	1.392 (5)
Br8—C10	1.891 (4)	C7—C12	1.401 (6)
Br9—C11	1.891 (5)	C8—C9	1.393 (6)
Br10—C12	1.891 (4)	C9—C10	1.386 (6)
O1—C6	1.379 (4)	C10—C11	1.406 (5)
O1—C7	1.393 (5)	C11—C12	1.392 (6)
C6—O1—C7	120.8 (3)	C8—C7—O1	114.8 (4)
C6—C1—C2	120.6 (4)	C8—C7—C12	120.2 (4)
C6—C1—Br1	117.9 (3)	O1—C7—C12	124.7 (3)
C2—C1—Br1	121.5 (3)	C7—C8—C9	119.9 (4)
C1—C2—C3	119.4 (4)	C7—C8—Br6	118.0 (3)
C1—C2—Br2	120.0 (3)	C9—C8—Br6	122.1 (3)
C3—C2—Br2	120.5 (3)	C10—C9—C8	120.3 (3)
C4—C3—C2	120.1 (3)	C10—C9—Br7	119.8 (3)
C4—C3—Br3	120.4 (3)	C8—C9—Br7	119.9 (3)
C2—C3—Br3	119.5 (3)	C9—C10—C11	119.9 (4)
C3—C4—C5	119.8 (3)	C9—C10—Br8	121.1 (3)
C3—C4—Br4	121.0 (3)	C11—C10—Br8	118.9 (3)
C5—C4—Br4	119.1 (3)	C12—C11—C10	119.9 (4)
C6—C5—C4	119.2 (4)	C12—C11—Br9	120.1 (3)
C6—C5—Br5	118.9 (3)	C10—C11—Br9	120.0 (3)
C4—C5—Br5	121.9 (3)	C11—C12—C7	119.6 (4)
O1—C6—C1	116.9 (3)	C11—C12—Br10	118.8 (3)
O1—C6—C5	122.5 (3)	C7—C12—Br10	121.6 (3)
C1—C6—C5	120.5 (3)
C6—C1—C2—C3	−1.2 (6)	C6—O1—C7—C8	147.4 (3)
Br1—C1—C2—C3	−177.8 (3)	C6—O1—C7—C12	−37.8 (6)
C6—C1—C2—Br2	175.9 (3)	O1—C7—C8—C9	176.3 (3)
Br1—C1—C2—Br2	−0.7 (5)	C12—C7—C8—C9	1.2 (6)
C1—C2—C3—C4	−3.5 (6)	O1—C7—C8—Br6	−4.1 (5)
Br2—C2—C3—C4	179.4 (3)	C12—C7—C8—Br6	−179.2 (3)
C1—C2—C3—Br3	178.7 (3)	C7—C8—C9—C10	1.6 (6)
Br2—C2—C3—Br3	1.6 (5)	Br6—C8—C9—C10	−178.0 (3)
C2—C3—C4—C5	3.1 (6)	C7—C8—C9—Br7	−179.9 (3)
Br3—C3—C4—C5	−179.0 (3)	Br6—C8—C9—Br7	0.4 (5)
C2—C3—C4—Br4	−178.1 (3)	C8—C9—C10—C11	−1.6 (6)
Br3—C3—C4—Br4	−0.3 (5)	Br7—C9—C10—C11	179.9 (3)
C3—C4—C5—C6	1.8 (6)	C8—C9—C10—Br8	179.4 (3)
Br4—C4—C5—C6	−177.0 (3)	Br7—C9—C10—Br8	0.9 (4)
C3—C4—C5—Br5	−178.6 (3)	C9—C10—C11—C12	−1.2 (6)
Br4—C4—C5—Br5	2.6 (5)	Br8—C10—C11—C12	177.9 (3)
C7—O1—C6—C1	125.6 (4)	C9—C10—C11—Br9	179.3 (3)
C7—O1—C6—C5	−58.3 (5)	Br8—C10—C11—Br9	−1.7 (4)
C2—C1—C6—O1	−177.6 (4)	C10—C11—C12—C7	3.9 (6)
Br1—C1—C6—O1	−0.9 (5)	Br9—C11—C12—C7	−176.6 (3)
C2—C1—C6—C5	6.2 (6)	C10—C11—C12—Br10	−172.9 (3)
Br1—C1—C6—C5	−177.1 (3)	Br9—C11—C12—Br10	6.6 (5)
C4—C5—C6—O1	177.6 (4)	C8—C7—C12—C11	−4.0 (6)
Br5—C5—C6—O1	−2.1 (6)	O1—C7—C12—C11	−178.5 (4)
C4—C5—C6—C1	−6.4 (6)	C8—C7—C12—Br10	172.8 (3)
Br5—C5—C6—C1	173.9 (3)	O1—C7—C12—Br10	−1.8 (6)