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In the low-temperature phase of di­bromo­mesityl­ene (1,3-di­bromo-2,4,6-tri­methyl­benzene), C9H10Br2, the mol­ecule deviates significantly from the C3h molecular symmetry encountered in tri­bromo­mesityl­ene (1,3,5-tri­bromo-2,4,6-tri­methyl­benzene), even for the endocyclic bond angles. An apparent C2v molecular symmetry is observed. The angle between the normal to the molecular plane and the normal to the (100) plane is ∼20°. The overall displacement was analysed at 120 K with rigid-body-motion tensor analysis. The methyl group located intermediate between the two Br atoms is rotationally disordered at both temperatures. This disorder was treated using two different approaches at 14 K, viz. the conventional split-atom model and a model using the special annular shapes of the atomic displacement parameters that are available in CRYSTALS [Watkin, Prout, Carruthers & Betteridge (1999). Issue 11. Chemical Crystallography Laboratory, Oxford, England], but only through the latter approach at 120 K. The disorder locally breaks the C2v molecular symmetry at 14 K only. Intra- and intermolecular contacts are described and discussed in relation to this methyl-group disorder. The bidimensional pseudo-hexagonal structural topology of tri­halogeno­mesityl­enes is altered in di­bromo­mesityl­ene insofar as the (100) molecular layers are undulated and are not coplanar as a result of an alternating tilt angle of ∼34° propagating along the [011] and [0\overline 11] directions between successive antiferroelectric molecular columns oriented roughly along the a axis.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103012666/fa1013sup1.cif
Contains datablocks global, 14K, 120K

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270103012666/fa101314Ksup2.hkl
Contains datablock 14K

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270103012666/fa1013120Ksup3.hkl
Contains datablock 120K

CCDC references: 219574; 219575

Comment top

Halogenomethylbenzenes are considered as prototype systems for studying the quantum rotational tunnelling behaviour (Prager & Heidemann, 1997) of methyl groups. The tunnel splitting, which acts as a local probe of molecular and crystal force fields, is used to test the relevance of numerical modelling (molecular dynamics, ab initio quantum chemistry calculations) of intra- and intermolecular potentials. In this context, it is of great interest, as a prerequisite to any subsequent studies, not only to establish the crystal structure of these compounds at room temperature but also to determine the conformations of the methyl groups and the nuclear density of their protons at low temperature (typically below 30 K). The use of neutron diffraction in this endeavour is essential. We have focused our investigations first on the threefold symmetric trihalogenomesitylenes (1,3,5-trihalogeno-2,4,6-trimethylbenzenes), namely 1,3,5-trichloro-, tribromo- and triiodo-2,4,6-trimethylbenzene [respectively trichloro- (TCM; Tazi et al., 1995), tribromo- (TBM; Meinnel et al., 2000) and triiodomesitylene (TIM; Boudjada et al., 2001, 2002)], which are triclinic at room temperature. Besides their interesting low-temperature dynamical properties, halogenomethylbenzenes are also studied because of their rich phase-transition properties. Orientational dynamic disorder is often encountered in the highest temperature phases (`plastic phases'; Kitaïgorodsky, 1973), and on heating or cooling, original phase transitions may occur (Fujiwara et al., 1990, Tazi, 1990).

Replacing one halogen substituent in trihalogenomesitylenes by, for instance, an H atom, lowers the molecular symmetry via the breaking of the C3 symmetry axis of the isolated molecule (disregarding the HMe atoms) and facilitates the study of the influence of the non-symmetric local molecular environment of the methyl groups on their quantum rotational tunnelling behaviour. With this fact as background, we report here a structural study of 1,3-dibromo-2,4,6-trimethylbenzene (dibromomesitylene, DBM), (I), at 120 and 14 K, from single-crystal neutron diffraction data. This work is the crystallographic counterpart of a numerical study of molecular structure and methyl-group rotational potential in halogenomesitylenes published elsewhere (Plazanet, 2001; Plazanet et al., 2002). The methyl-group tunnelling behaviour of (I) was first studied by inelastic neutron scattering (INS; Meinnel et al., 1995). A quasi-free quantum-rotor behaviour was evidenced for the methyl group between the two Br atoms, as reflected by a large tunnelling splitting of 0.39 meV, and a hindering potential with a predominant sixfold symmetry was proposed. In addition, (I) undergoes a reconstructive phase transition near room temperature (between 293 and 301 K); hence, both of the present structure determinations will refer to the low-temperature phase of the title compound, the structure of the high-temperature phase (probably a plastic phase) being unknown. The 14 K structure will be considered as the `reference structure' of the low-temperature phase of (I); the following discussion will be based on the parameters of this phase, unless otherwise noted.

The conformation of (I) (Fig. 1) is characterized mainly by a significant distortion of the endocyclic angles of the aromatic ring from ideal D6 h symmetry, the endocyclic angles being narrowed by a donor substituent such as CH3 and enlarged for a Car atom linked to an acceptor like a halogen (Domenicano et al., 1975). This deformation, which has already been encountered in TCM, TBM or TIM with C3 h symmetry, is much less symmetric here because of the inequivalence of the substituents at the 1-, 3- and 5-positions on the benzene ring. Indeed, a C2v symmetry can be discerned in (I) from the distortion of the endocyclic angles, viz. for atoms with methyl substituents, 117.08 (11)° on average for atoms C4 and C6, and 115.77 (5)° for atom C2, and for atoms bonded to bromine, 123.60 (7)° on average for atom C1 and C3; the angle is 122.87 (5)° for atom C5 linked to atom H51. In other words, it transpires that (disregarding the HMe atoms) a molecular mirror plane perpendicular to the benzene ring runs through atoms C7, C2, C5 and H51. The intersection of this mirror plane with the plane of the ring is the twofold axis of the C2v symmetry. Such a description in terms of simple symmetry considerations is roughly corroborated by the values of the exocyclic angles, which on either side of the C2 axis are equal to within 0.15°. Note that these slight deviations from the apparent C2v symmetry concerning the exocyclic angles increase progressively on traversing the line from atom H51 to atom C7 (from ±0.006 to ±0.43°, respectively). The average intramolecular bond lengths [Car—Br = 1.905 (3), Car—Car = 1.398 (2) and Car—CMe = 1.500 (2) Å], as well as the single-? bond length Car—H [1.091 (2) Å], agree with the distances reported in the literature.

We have computed the best least-squares plane (unit weights) through the 12 non-HMe atoms using the MOLAX routine in CRYSTALS (Watkin et al., 1999a). The angle between the normal to the (1 0 0) plane and the normal to the molecular plane is found to be 19.83°. While deviations from this plane are negligible for the benzene C atoms [mean absolute value = 0.005 (1) Å] and for atom H51 [0.010 (2) Å], it appears that atom Br2 is significantly more out-of-plane than atom Br1 [−0.032 (1) versus 0.009 (1) Å]; the same conclusion can be drawn for atom C9 of the methyl group trans to Br2 [−0.026 (1) versus 0.013 (1) and 0.009 (1) Å for atoms C7 and C8, respectively]. The refinement of the occupancies of the substituted groups, i.e. the Br atoms, atom H51 and the CMe atoms, reveals no deviation (within the s.u. values) from the site-symmetry multiplicity. The low-temperature phase of (I) is therefore well ordered, without any orientational disorder of the whole molecule.

For the 120 K data, we performed a conventional TLS analysis using the CRYSTALS program (Watkin et al., 1999a). The overall rigid-body motion tensors T, L and S (Schomaker & Trueblood, 1968) were least-squares fitted to the individual anisotropic displacement parameters. In order to obtain a reasonably good overall R factor for Uij (0.126), it was necessary to exclude all the HMe atoms from the TLS calculation. Nevertheless, when atom H51 is removed from the calculation, the R factor for Uij decreases significantly to 0.041, while the main TLS features remain unchanged. The diagonal values of the translational (T) and screw (S) tensors, with respect to the principal axes of the librational (L) tensor, are negligible, while those of the L tensor are L11 = 1.4, L22 = 4.8 and L33 = 9.6°2. The centre of libration is close to the centre of gravity of the molecule. Axis 1 makes an angle of approximately 10° with the ring plane and is roughly perpendicular to the C5—C6 bond; axis 2 makes an angle of 42° with the normal to the ring plane in a plane containing the C6—C9 bond; axis 3 makes an angle of 75° with the normal to the ring plane in a plane perpendicular to the C3—C4 bond. At 14 K, the Uij values are too small to permit convergence of the least-squares fitting.

The most striking crystallographic features of the low-temperature phase of (I) are the particular conformations of the three methyl groups with regard to the benzene ring, and the nuclear density of the HMe atoms. The experimental nuclear densities of the H atoms for each methyl group were determined by setting their occupancies to zero, refining the scale factor only and performing a difference Fourier synthesis in their plane [e.g. see Fig. 2 of Plazanet et al. (2002); the proton nuclear densities of the C7 methyl group at 120 and 14 K correspond to the observed structure factors multiplied by −1]. On the one hand, the H atoms of methyl groups C8 and C9 appear localized around three sites, but their nuclear densities are much more diffuse than those of the C atoms to which they are linked: the H-atom Ueq parameters are 2.1–5.3 times larger than those of atoms C8 or C9. Both of these methyl groups are `eclipsed', i.e. atoms H81 and H91 are located in the plane of the aromatic ring, with relevant torsion angles of 1.71 and 2.26°, respectively; they? point at atom H51, and display the highest Ueq parameter of the methyl groups. This configuration allows the minimization of intramolecular HMe···Br interactions for the C8 and C9 methyl groups [minimum contact distance of 2.996 (3) and 2.959 (3) Å for H82···Br2 and H93···Br1, respectively], which can be compared with those for the C7 methyl group [minimum contact distances of 2.586 (4) and 2.572 (6) Å for H71···Br2 and H76···Br1, respectively]. The aforementioned apparent C2v symmetry is thus fulfilled here to a high degree of exactitude, as illustrated by the almost equal values of the C4—C8—H81 and C6—C9—H91 angles [110.75 (11) and 110.79 (9)°, respectively]. Note that for trihalogenomesitylenes, C3 h and Cs symmetries are quasi- equally probable in isolated molecules and a C2v symmetry may be stabilized in the crystalline state, as encountered in TIM (Boudjada et al., 2002). The CMe—H bond length is systematically, though slightly, longer for staggered protons than for eclipsed ones, e.g. 1.092 (2) and 1.094 (2) Å for C8—H82 and C8—H83, respectively, versus 1.089 (2) Å for C8—H81. Hence, the C8 and C9 methyl groups do not exhibit perfect threefold symmetry, ?as predicted by density functional theory (DFT) and all quantum-mechanical calculations (Meinnel et al., 2000; Boudjada et al., 2002). On the other hand, the C7 methyl group, situated between the two Br atoms, behaves differently from the C8 and C9 methyl moieties. The proton nuclear density of the C7 group is, indeed, much more diffuse and strongly anisotropic – even at 14 K – in the sense that three damped maxima emerge from a distorted annulus. The split-atom model corresponds to two overlapped pseudomethyl groups at 60° to one other, both eclipsed with the ring plane, viz. one with an average occupancy of 2/3 [mean value 0.68 (2) for atoms H71, H72 and H73] and the other with an occupancy of 1/3 [mean value 0.32 (2) for atoms H74, H75 and H76]. This description is equivalent to that obtained from the special shape model [three split atoms (H71, H72 and H73) with a mean occupancy of 0.36 (2) plus a homogeneous ring with an occupancy of 1.92 (3)]. However, the real nuclear density along the H-atom rotational path, which is clearly inhomogeneous at 14 K, and which is predicted to be divided among six sites for one methyl group from INS experiments (Meinnel et al., 1995) and from DFT calculations (Plazanet et al., 2002), is better accounted for by the split-atom model (for which the three HMe sites lying between the principal congeners are refined with individual occupancies) than by the special shape function. In any case, the apparent C2v symmetry, which is approximately fulfilled by the rest of the molecule, is broken locally at 14 K by the H-atom nuclear density of the C7 methyl group. The occupancy of the H75(H74) site is approximately one-half that of the H73(H72) site; the two pairs of sites are thus not related by a mirror plane. In other words, at 14 K, the three most occupied HMe sites (H71, H72 and H73) – which correspond to the three main maxima of Fig. 2 b of Plazanet et al. (2002) – break the C2v molecular symmetry because one of them, atom H71, is eclipsed and points towards atom Br2. However, this molecular symmetry breaking is not encountered at 120 K, insofar as the C7 methyl group H atoms are significantly delocalized, their nuclear densities forming an almost perfect ring [see Fig. 2a of Plazanet et al. (2002)]. The delocalization of the HMe atoms, although present at low temperature, is dynamic and reflects the quantum rotational tunnelling of the methyl groups coupled to their classical thermal motions and those of the whole molecule.

The structure of (I) can be described as a stacking of undulated molecular layers perpendicular to the a axis (at x/a 1/4 and 3/4) forming molecular columns propagated in the direction of that axis (Figs. 2 and 3). In these columns, the arrangement is `antiferroelectric'; a given molecule is sandwiched between two molecules generated by as many inversion centers and belonging to adjacent layers. Atoms Br1 and Br2 are more or less directly below the C8 and C9 methyl groups, respectively (a-projected shift 0.75 Å), while – because the CMe—H bond length is shorter than the C—Br bond – atom H51 is almost exactly below the disordered C7 methyl groups. Such a structural topology is encountered at room temperature in triclinic TBM (Meinnel al., 2000) and TIM (Boudjada et al., 2001, 2002), but while in the latter two compounds the molecular layers are flat, with each molecule lying in the (1 0 0) planes to within 5°, in the title compound, the normal to the ring plane is tilted by 20° with respect to the a axis (see above). This tilt induces an undulation of the molecules within the (1 0 0) planes: along the [0 1 1] and [0 − 1 1] directions, two successive a axis-oriented antiferroelectric molecular columns are tilted by 34.30°. Consequently, the pseudohexagonal arrangement in the molecular layers that is typical of trihalogenomesitylenes (Boudjada et al., 2002) and hexamethylbenzene (Hamilton et al., 1969) is significantly modified in (I). Indeed, one molecule is surrounded by six neighbours in such a way that the C7, C8 and C9 methyl groups of neighbouring molecules are opposite one another, as are atoms Br1, Br2 and H51. However, because of the tilt of the molecules in (I), the triangular contacts differ from those in TBM and TIM (the symmetry operations for the atoms involved in these contacts can be found in the supplementary material); the Br···Br contact distance is increased [3.767 (3) versus mean 3.572 Å in TBM], and the intermolecular C7···C9 and C8···C9 distances are significantly shortened, whereas the C7···C8 contact distance is almost unchanged [3.762 (4), 3.768 (4) and 4.084 (4) Å, respectively, versus a mean of 4.074 Å in TBM]. Atom H51 is 4.103 (4) and 3.114 (4) Å from atoms Br1 and Br2 of neighbouring molecules, respectively. More specifically, the eclipsed atoms H81 and H91 point towards atoms Br1 and Br2, respectively, of neighbouring molecules, [contact distances of 3.199 (3) and 2.978 (3) Å, compared with short intermolecular C8···Br1 and C9···Br2 contacts of 4.185 (4) and 3.963 (4) Å, respectively], while the shortest C7···Br contact distance in the (1 0 0) planes is 4.316 (6) Å. For molecules in different layers, it transpires that the minimum intermolecular distances, compared with the distances between molecules in the same layer, are significantly increased for the Br···Br and H51···Br contacts. The C7 and C8 methyl groups are involved in short H51···HMe contacts? [e.g. H51···H74 and H51···H83 of 2.817 (5) and 2.835 (3) Å, respectively], but the strongest van der Waals (vdW) interactions (Bondi, 1964) occur for HMe···Br (sum of vdW radii = 3.05 Å); the minimum contact distances are 2.913 (4) and 2.952 (4) Å for H82···Br1 and H93···Br2, versus 3.029 (3) Å for H72···Br1. In summary, what distinguishes the C7 methyl group from its C8 and C9 analogues – from a structural point of view – can be explained by its symmetrical molecular and crystal environment. Indeed, within a molecule, this methyl group – which lies on the C2 molecular symmetry axis – is flanked by two Br atoms and, in the molecular columns, is sandwiched between two H51 atoms. The C7 methyl group therefore experiences stronger symmetric HMe···Br intramolecular interactions. It should be stressed that the HMe···Br intermolecular interactions are slightly weaker for the C7 methyl group than for the C8 and C9 groups. The significant Me···Me intermolecular coupling (sum of vdW radii = 2.40 Å) does not differ? between the C7 and the C8 and C9 methyl groups but appears stronger than that in TBM [minimum HMe···HMe intermolecular contact distance of 2.351 (5) Å in (I) for H75···H92 versus 2.764 Å in TBM].

Experimental top

Single crystals of (I) were grown by slow cooling (from 273 K) of a saturated dibromomesitylene solution in chlorobenzene. A single-crystal suitable for neutron diffraction data collection was kept below the phase-transition temperature (around 297 K) throughout the experiment.

Refinement top

The low-temperature structure of (I) was solved initially at 120 K from single-crystal X-ray diffraction data (Nonius KappaCCD diffractometer) by direct methods (SHELXS97; Sheldrick, 1997) and subsequent least-squares refinements (CRYSTALS; Watkin et al., 1999a) [P21/n; a = 7.735 (2) Å, b = 14.477 (3) Å, c = 8.960 (2) Å and β = 112.87 (3)°; R = 0.0588, wR = 0.0669 and S = 1.04; Δρmin = −2.09 e Å−3 and Δρmax = 1.48 e Å−3; 102 least-squares parameters versus 1489 independent reflections used]. The present structures of (I) at 120 and 14 K were refined from neutron diffraction data using the X-ray results as a starting model. The significant disorder affecting the H atoms of the C7 methyl group was treated at 14 K using two different approaches, viz. a conventional split-atom model and a special shape (ring) of the ADPs available in CRYSTALS (Watkin et al., 1999a), but only the latter approach was used at 120 K. At 14 K, the sum of the occupancies of the different pseudo-atoms was constrained to be equal to 3, and the C—H distances were restricted to 1.09 Å. In the first approach (220 least-squares parameters), six sites were refined with conventional anisotropic ADPs; in the second (200 least-squares parameters), only three sites with conventional anisotropic ADPs were refined plus one site with a ring-shaped ADP defined by its thickness, radius [1.024 (2) Å], declination and azimuthal angles. The split-atom model, despite having a higher number of parameters, allows a better description of the H-atom nuclear densities at 14 K than the special-shape model (Δρmin = −0.97 versus −1.32 F m Å−3, respectively). On the other hand, at 120 K, only one site with a ring-shaped ADP can be properly described for the quasi-ideal ring-shaped nuclear densities of the three individually imperceptible C7 methyl-group H atoms [radius of the ring = 1.030 (3) Å].

Computing details top

For both compounds, data reduction: PRON (Scherf, 1998); program(s) used to refine structure: CRYSTALS (Watkin et al., 1999a); molecular graphics: CAMERON (Watkin, Prout & Pearce, 1999b). Software used to prepare material for publication: CRYSTALS I (Watkin et al., 1999a) for (14K); CRYSTALS (Watkin et al., 1999a) for 120K.

Figures top
[Figure 1] Fig. 1. A view of (I) at 14 K showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2] Fig. 2. The packing of (I) at 14 K, viewed along the c axis. Displacement ellipsoids are drawn at the 30% probability level.
[Figure 3] Fig. 3. The packing of (I) at 14 K, viewed along the a axis. Displacement ellipsoids are drawn at the 30% probability level.
(14K) 1,3-dibromo-2,4,6-trimethylbenzene top
Crystal data top
C9H10Br2F(000) = 144.056
Mr = 277.99Dx = 2.034 Mg m3
Monoclinic, P21/nNeutron radiation, λ = 0.83080 Å
a = 7.691 (13) ÅCell parameters from 12 reflections
b = 14.41 (2) Åθ = 36.0–42.0°
c = 8.909 (11) ŵ = 0.39 mm1
β = 113.13 (2)°T = 14 K
V = 908 (2) Å3Prism, white
Z = 43.5 × 3.0 × 3.0 mm
Data collection top
Orphée reactor (Saclay, France): 5C2 four-circle
diffractometer
2347 reflections with I > 3σ(I)
Radiation source: Orphée reactor Saclay FranceRint = 0.017
Copper (2 2 0) monochromatorθmax = 37.5°, θmin = 3.3°
ω scansh = 112
3875 measured reflectionsk = 021
2998 independent reflectionsl = 1213
Refinement top
Refinement on FAll H-atom parameters refined
Least-squares matrix: full Chebychev polynomial with 4 parameters, Carruthers & Watkin, 1979, 1.06 -1.33 0.828 -.330
R[F2 > 2σ(F2)] = 0.026(Δ/σ)max = 0.002
wR(F2) = 0.023Δρmax = 0.65 e Å3
S = 1.16Δρmin = 0.97 e Å3
2347 reflectionsExtinction correction: Eq. 22, Larson, 1970
224 parametersExtinction coefficient: 17.4 (3)
30 restraints
Crystal data top
C9H10Br2V = 908 (2) Å3
Mr = 277.99Z = 4
Monoclinic, P21/nNeutron radiation, λ = 0.83080 Å
a = 7.691 (13) ŵ = 0.39 mm1
b = 14.41 (2) ÅT = 14 K
c = 8.909 (11) Å3.5 × 3.0 × 3.0 mm
β = 113.13 (2)°
Data collection top
Orphée reactor (Saclay, France): 5C2 four-circle
diffractometer
2347 reflections with I > 3σ(I)
3875 measured reflectionsRint = 0.017
2998 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02630 restraints
wR(F2) = 0.023All H-atom parameters refined
S = 1.16Δρmax = 0.65 e Å3
2347 reflectionsΔρmin = 0.97 e Å3
224 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Br10.24819 (7)0.10724 (3)0.79692 (6)0.0041
Br20.35755 (7)0.20748 (3)0.45279 (6)0.0046
C10.24067 (7)0.04928 (3)0.60247 (6)0.0045
C20.29775 (7)0.04353 (3)0.60786 (6)0.0047
C30.28868 (7)0.08093 (3)0.45948 (6)0.0046
C40.22961 (7)0.03068 (3)0.31396 (6)0.0046
C50.17541 (7)0.06122 (3)0.31896 (6)0.0052
C60.17823 (7)0.10320 (3)0.46084 (6)0.0047
C70.36385 (8)0.09864 (4)0.76300 (6)0.0081
C80.22115 (8)0.07206 (4)0.15666 (6)0.0067
C90.11629 (7)0.20211 (4)0.45790 (6)0.0071
H510.1284 (2)0.10197 (9)0.20678 (14)0.0202
H710.4070 (6)0.16796 (15)0.7499 (3)0.05240.709 (18)
H720.4808 (4)0.0642 (2)0.8573 (3)0.03980.650 (16)
H730.2501 (3)0.1032 (3)0.8070 (3)0.04080.670 (17)
H740.5051 (5)0.1251 (5)0.7871 (7)0.04300.309 (16)
H750.2728 (8)0.1581 (3)0.7515 (7)0.04320.298 (17)
H760.3718 (12)0.0596 (3)0.8690 (4)0.06570.364 (18)
H810.1738 (3)0.0208 (1)0.05907 (16)0.0274
H820.3592 (2)0.09783 (12)0.16766 (18)0.0265
H830.1243 (2)0.13123 (11)0.12132 (19)0.0279
H910.0681 (3)0.2304 (1)0.33527 (17)0.0290
H920.2325 (2)0.2451 (1)0.5381 (2)0.0282
H930.0020 (2)0.20862 (11)0.5008 (2)0.0276
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.00440 (18)0.00446 (18)0.00324 (16)0.00048 (14)0.00139 (13)0.00135 (14)
Br20.00623 (18)0.00261 (17)0.00555 (18)0.00101 (14)0.00293 (15)0.00019 (13)
C10.00580 (19)0.00385 (19)0.00360 (18)0.00040 (14)0.00154 (15)0.00035 (14)
C20.00603 (19)0.00404 (19)0.00374 (18)0.00086 (14)0.00148 (15)0.00068 (14)
C30.00548 (19)0.00384 (18)0.00408 (17)0.00053 (14)0.00154 (15)0.00000 (14)
C40.00548 (19)0.00436 (18)0.00364 (18)0.00062 (15)0.00148 (14)0.00010 (14)
C50.00700 (19)0.00427 (19)0.00424 (18)0.00081 (15)0.00198 (15)0.00024 (14)
C60.00597 (19)0.00378 (18)0.00450 (18)0.00085 (14)0.00214 (14)0.00010 (14)
C70.0111 (2)0.0073 (2)0.00498 (19)0.00145 (17)0.00210 (16)0.00214 (16)
C80.0088 (2)0.0067 (2)0.00480 (18)0.00076 (16)0.00287 (16)0.00038 (15)
C90.0092 (2)0.00434 (19)0.0082 (2)0.00195 (16)0.00382 (17)0.00048 (15)
H510.0303 (6)0.0168 (5)0.0128 (4)0.0055 (4)0.0077 (4)0.0056 (4)
H710.112 (6)0.0226 (14)0.0253 (13)0.034 (2)0.030 (2)0.010 (1)
H720.043 (2)0.0404 (19)0.0170 (13)0.0187 (14)0.0089 (11)0.0059 (12)
H730.0324 (15)0.063 (4)0.0366 (19)0.0113 (16)0.0235 (13)0.024 (2)
H740.032 (3)0.058 (7)0.040 (4)0.024 (3)0.016 (3)0.032 (4)
H750.041 (5)0.033 (5)0.035 (3)0.025 (4)0.007 (3)0.021 (3)
H760.148 (16)0.032 (3)0.020 (3)0.034 (6)0.036 (5)0.005 (2)
H810.0451 (8)0.0223 (6)0.0147 (5)0.0097 (6)0.0114 (5)0.0065 (4)
H820.0190 (5)0.0376 (7)0.0243 (5)0.0085 (5)0.0099 (4)0.0042 (5)
H830.0330 (7)0.0257 (6)0.0272 (6)0.0150 (5)0.0141 (5)0.0111 (5)
H910.0476 (9)0.0213 (6)0.0174 (5)0.0114 (6)0.0121 (6)0.0080 (4)
H920.0248 (6)0.0176 (6)0.0361 (7)0.0047 (5)0.0056 (5)0.0078 (5)
H930.0282 (6)0.0233 (6)0.0417 (8)0.0062 (5)0.0247 (6)0.0022 (5)
Geometric parameters (Å, º) top
Br1—C11.9037 (19)C7—H711.073 (2)
Br2—C31.906 (3)C7—H721.0801 (18)
C1—C21.4025 (19)C7—H731.092 (2)
C1—C61.3967 (14)C7—H741.090 (2)
C2—C31.4038 (15)C7—H751.085 (2)
C2—C71.4993 (15)C7—H761.080 (2)
C3—C41.3962 (14)C8—H811.0890 (17)
C4—C51.3943 (19)C8—H821.0921 (19)
C4—C81.5008 (16)C8—H831.0938 (18)
C5—C61.3939 (15)C9—H911.0860 (18)
C5—H511.0911 (16)C9—H921.0909 (17)
C6—C91.500 (2)C9—H931.0912 (18)
Br1···H82i2.913 (4)C4···C4i4.270 (4)
Br1···H72ii3.029 (3)C4···C6i4.322 (5)
Br1···H81iii3.199 (3)C4···H83xi4.427 (4)
Br1···H83iv3.240 (4)C4···H76iv4.451 (9)
Br1···H91v3.314 (4)C4···C6iv4.461 (4)
Br1···H76ii3.322 (7)C4···C5i4.480 (5)
Br1···H93v3.371 (4)C4···H51xi4.486 (5)
Br1···H75vi3.405 (7)C5···H73iv3.074 (5)
Br1···H71vi3.421 (5)C5···H74i3.098 (5)
Br1···H74ii3.446 (7)C5···H81xi3.434 (3)
Br1···C4iv3.584 (4)C5···H75iv3.539 (8)
Br1···Br2vi3.767 (3)C5···H72i3.567 (5)
Br1···C9v3.798 (4)C5···C3i3.817 (5)
Br1···C8iv3.825 (5)C5···H71i3.821 (6)
Br1···C5iv3.864 (4)C5···H83xi3.823 (4)
Br1···C3iv3.873 (5)C5···C2i3.851 (5)
Br1···C7ii3.886 (4)C5···Br1iv3.864 (4)
Br1···H71ii3.961 (5)C5···H76iv3.87 (1)
Br1···C8i3.969 (5)C5···C1iv3.876 (4)
Br1···H73ii4.080 (5)C5···C7i3.926 (5)
Br1···H92v4.090 (4)C5···C2iv3.949 (5)
Br1···H51iii4.103 (4)C5···C7iv3.955 (5)
Br1···H81iv4.123 (4)C5···Br2i3.967 (4)
Br1···H51iv4.171 (4)C5···Br2xii4.069 (4)
Br1···C8iii4.185 (4)C5···C8xi4.139 (4)
Br1···H74vi4.253 (9)C5···H92xiii4.354 (4)
Br1···H82iii4.261 (4)C5···H76i4.417 (9)
Br1···H73vi4.276 (7)C5···C4i4.480 (5)
Br1···H81i4.298 (6)C6···H73iv3.220 (4)
Br1···C7vi4.316 (6)C6···H75iv3.329 (7)
Br1···H75ii4.319 (6)C6···C2iv3.571 (5)
Br1···C6iv4.394 (4)C6···Br2i3.665 (4)
Br1···C2iv4.425 (4)C6···C1iv3.754 (4)
Br2···H93iv2.952 (4)C6···H82i3.790 (4)
Br2···H91vii2.978 (3)C6···C7iv3.851 (5)
Br2···H83viii3.073 (3)C6···C3i3.889 (5)
Br2···H51vii3.114 (4)C6···H74i3.890 (5)
Br2···H92i3.168 (4)C6···C3iv3.937 (5)
Br2···H74ix3.493 (5)C6···H76iv4.142 (9)
Br2···C6i3.665 (4)C6···H75vi4.218 (6)
Br2···H71ix3.684 (5)C6···H91v4.244 (4)
Br2···Br1x3.767 (3)C6···H71iv4.244 (6)
Br2···C9i3.805 (5)C6···C6iv4.284 (4)
Br2···C9vii3.963 (4)C6···H83xii4.285 (5)
Br2···C5i3.967 (4)C6···C4i4.322 (5)
Br2···C1i4.022 (4)C6···H71i4.390 (6)
Br2···C9iv4.024 (5)C6···H71vi4.390 (5)
Br2···C5vii4.069 (4)C6···C2i4.392 (5)
Br2···H91i4.078 (6)C6···Br1iv4.394 (4)
Br2···C8viii4.150 (4)C6···H82xii4.438 (6)
Br2···H92vii4.207 (5)C6···C4iv4.461 (4)
Br2···H51i4.210 (4)C7···H92x3.129 (3)
Br2···H72ix4.243 (6)C7···H93iv3.280 (3)
Br2···H91iv4.387 (5)C7···H93x3.392 (4)
Br2···C7ix4.476 (4)C7···H82i3.449 (4)
C1···H82i3.033 (4)C7···H82iii3.620 (4)
C1···C1iv3.707 (4)C7···H91iv3.622 (4)
C1···C6iv3.754 (4)C7···H81iii3.658 (3)
C1···C2iv3.817 (5)C7···H81i3.700 (4)
C1···C4i3.852 (5)C7···C9iv3.744 (4)
C1···C8i3.855 (5)C7···C9x3.762 (4)
C1···C5iv3.876 (4)C7···H51i3.808 (5)
C1···C3i3.896 (5)C7···C6iv3.851 (5)
C1···C3iv3.914 (5)C7···H76ii3.853 (6)
C1···C4iv3.978 (5)C7···C8i3.867 (4)
C1···Br2i4.022 (4)C7···Br1ii3.886 (4)
C1···H91v4.077 (4)C7···H51iv3.899 (5)
C1···H93iv4.098 (5)C7···H72ii3.899 (5)
C1···H73iv4.164 (5)C7···C4i3.924 (4)
C1···H75iv4.268 (7)C7···C5i3.926 (5)
C1···H81i4.344 (5)C7···C5iv3.955 (5)
C1···H81iii4.413 (5)C7···C8iii4.084 (4)
C1···H51iv4.414 (4)C7···H91x4.205 (4)
C1···H75vi4.427 (7)C7···H83iii4.293 (4)
C1···H72ii4.439 (5)C7···Br1x4.316 (6)
C1···C9iv4.448 (5)C7···Br2viii4.476 (4)
C1···H76ii4.478 (6)C8···H72i3.058 (4)
C2···H93iv3.187 (4)C8···H81xi3.182 (3)
C2···H82i3.311 (3)C8···H76xiv3.205 (6)
C2···C6iv3.571 (5)C8···H73xiv3.241 (4)
C2···C4i3.585 (5)C8···H92vii3.251 (4)
C2···C9iv3.773 (4)C8···H91vii3.262 (4)
C2···C1iv3.817 (5)C8···H51xi3.325 (3)
C2···C8i3.843 (4)C8···H74i3.453 (8)
C2···C5i3.851 (5)C8···H76i3.744 (9)
C2···C3i3.898 (4)C8···C9vii3.768 (4)
C2···C5iv3.949 (5)C8···Br1iv3.825 (5)
C2···H91iv4.067 (4)C8···C2i3.843 (4)
C2···H81i4.087 (4)C8···C1i3.855 (5)
C2···H51i4.146 (5)C8···C7i3.867 (4)
C2···H51iv4.292 (4)C8···H72xiv3.911 (5)
C2···C6i4.392 (5)C8···Br1i3.969 (5)
C2···C2iv4.396 (5)C8···H75xiv3.981 (9)
C2···Br1iv4.425 (4)C8···C8xi4.027 (3)
C2···C2i4.432 (4)C8···H83xi4.075 (4)
C2···H92x4.457 (4)C8···C7xiv4.084 (4)
C2···H81iii4.493 (5)C8···C5xi4.139 (4)
C3···H93iv3.022 (3)C8···Br2ix4.150 (4)
C3···C4i3.809 (4)C8···Br1xiv4.185 (4)
C3···C5i3.817 (5)C8···H93vii4.340 (4)
C3···C3i3.832 (4)C8···H71i4.355 (6)
C3···Br1iv3.873 (5)C8···H93iv4.500 (4)
C3···C9iv3.885 (4)C9···H75iv2.907 (5)
C3···C6i3.889 (5)C9···H75vi3.124 (5)
C3···C1i3.896 (5)C9···H82xii3.125 (4)
C3···C2i3.898 (4)C9···H73iv3.212 (4)
C3···C1iv3.914 (5)C9···H71vi3.269 (4)
C3···C6iv3.937 (5)C9···H83xii3.369 (3)
C3···H91vii4.216 (4)C9···H73vi3.410 (5)
C3···H82i4.235 (4)C9···H74vi3.728 (6)
C3···H51i4.308 (5)C9···H71iv3.743 (6)
C3···H74i4.346 (7)C9···C7iv3.744 (4)
C3···H92i4.369 (5)C9···H76vi3.750 (7)
C3···H72i4.406 (4)C9···C7vi3.762 (4)
C3···H91iv4.410 (4)C9···C8xii3.768 (4)
C4···H74i3.384 (7)C9···C2iv3.773 (4)
C4···H72i3.439 (4)C9···Br1xiii3.798 (4)
C4···Br1iv3.584 (4)C9···Br2i3.805 (5)
C4···C2i3.585 (5)C9···H92xiii3.822 (4)
C4···H81xi3.622 (3)C9···C3iv3.885 (4)
C4···C3i3.809 (4)C9···H91v3.892 (4)
C4···H93iv3.845 (3)C9···H72vi3.946 (5)
C4···C1i3.852 (5)C9···Br2xii3.963 (4)
C4···H73iv3.920 (5)C9···Br2iv4.024 (5)
C4···C7i3.924 (4)C9···H76iv4.266 (8)
C4···C1iv3.978 (5)C9···H81xii4.332 (5)
C4···H71i4.192 (5)C9···H82i4.369 (4)
C4···H91vii4.203 (4)C9···H74i4.412 (5)
C4···H76i4.204 (9)C9···C1iv4.448 (5)
Br1—C1—C2119.34 (9)H72—C7—H7463.0 (4)
Br1—C1—C6117.06 (9)H73—C7—H74141.7 (3)
C2—C1—C6123.60 (5)C2—C7—H75111.0 (3)
C1—C2—C3115.77 (5)H71—C7—H7558.1 (4)
C1—C2—C7121.65 (5)H72—C7—H75138.1 (3)
C3—C2—C7122.58 (9)H73—C7—H7553.7 (4)
Br2—C3—C2119.02 (4)H74—C7—H75107.4 (2)
Br2—C3—C4117.39 (4)C2—C7—H76114.4 (3)
C2—C3—C4123.59 (9)H71—C7—H76131.8 (3)
C3—C4—C5117.08 (11)H72—C7—H7648.5 (4)
C3—C4—C8122.7 (1)H73—C7—H7659.7 (4)
C5—C4—C8120.22 (5)H74—C7—H76107.5 (2)
C4—C5—C6122.87 (5)H75—C7—H76107.8 (2)
C4—C5—H51118.53 (8)C4—C8—H81110.75 (11)
C6—C5—H51118.60 (11)C4—C8—H82111.55 (11)
C1—C6—C5117.09 (11)H81—C8—H82108.10 (15)
C1—C6—C9122.6 (1)C4—C8—H83110.69 (11)
C5—C6—C9120.33 (9)H81—C8—H83108.84 (16)
C2—C7—H71113.56 (17)H82—C8—H83106.77 (14)
C2—C7—H72110.55 (16)C6—C9—H91110.79 (9)
H71—C7—H72108.28 (17)C6—C9—H92110.8 (1)
C2—C7—H73109.48 (14)H91—C9—H92108.30 (15)
H71—C7—H73108.0 (2)C6—C9—H93111.69 (12)
H72—C7—H73106.7 (2)H91—C9—H93108.44 (14)
C2—C7—H74108.5 (3)H92—C9—H93106.67 (17)
H71—C7—H7450.9 (4)
Symmetry codes: (i) x+1, y, z+1; (ii) x+1, y, z+2; (iii) x, y, z+1; (iv) x, y, z+1; (v) x+1/2, y+1/2, z+1/2; (vi) x+1/2, y+1/2, z+3/2; (vii) x+1/2, y1/2, z+1/2; (viii) x+1/2, y1/2, z+1/2; (ix) x1/2, y1/2, z1/2; (x) x+1/2, y1/2, z+3/2; (xi) x, y, z; (xii) x+1/2, y+1/2, z+1/2; (xiii) x1/2, y+1/2, z1/2; (xiv) x, y, z1.
(120K) 1,3-dibromo-2,4,6-trimethylbenzene top
Crystal data top
C9H10Br2F(000) = 144.056
Mr = 277.99Dx = 2.013 Mg m3
Monoclinic, P21/nNeutron radiation, λ = 0.83080 Å
a = 7.721 (14) ÅCell parameters from 11 reflections
b = 14.46 (3) Åθ = 35.0–41.0°
c = 8.924 (17) ŵ = 0.39 mm1
β = 112.87 (2)°T = 120 K
V = 918 (3) Å3Prism, white
Z = 43.5 × 3.0 × 3.0 mm
Data collection top
Orphée reactor (Saclay, France): 5C2 four-circle
diffractometer
1490 reflections with I > 3σ(I)
Radiation source: Orphée reactor Saclay FranceRint = 0.017
Copper (2 2 0) monochromatorθmax = 35.0°, θmin = 3.3°
ω scansh = 102
3242 measured reflectionsk = 019
2547 independent reflectionsl = 1112
Refinement top
Refinement on FAll H-atom parameters refined
Least-squares matrix: full Chebychev polynomial with 4 parameters, Carruthers & Watkin, 1979, 1.93 -3.51 1.59 -1.06
R[F2 > 2σ(F2)] = 0.032(Δ/σ)max = 0.000397
wR(F2) = 0.024Δρmax = 1.42 e Å3
S = 1.06Δρmin = 1.17 e Å3
1490 reflectionsExtinction correction: Eq. 22, Larson, 1970
169 parametersExtinction coefficient: 13.2 (4)
0 restraints
Crystal data top
C9H10Br2V = 918 (3) Å3
Mr = 277.99Z = 4
Monoclinic, P21/nNeutron radiation, λ = 0.83080 Å
a = 7.721 (14) ŵ = 0.39 mm1
b = 14.46 (3) ÅT = 120 K
c = 8.924 (17) Å3.5 × 3.0 × 3.0 mm
β = 112.87 (2)°
Data collection top
Orphée reactor (Saclay, France): 5C2 four-circle
diffractometer
1490 reflections with I > 3σ(I)
3242 measured reflectionsRint = 0.017
2547 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0320 restraints
wR(F2) = 0.024All H-atom parameters refined
S = 1.06Δρmax = 1.42 e Å3
1490 reflectionsΔρmin = 1.17 e Å3
169 parameters
Special details top

Refinement. The cif explains in the vrf that there is special treatment of H70 The C—H70 'bond' should point to the centroid of the 3 disordered H atoms. The CRYSTALS implementation permits partial normal atoms to be embedded in the 'special shape', (with total occupancy fixed) so that quite complex bumpy surfaces can be simulated, e.g. hindered rotors.

Unofficial CIF items to describe this disordered methyl group would then be:-

loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_occupancy _atom_site_adp_type H70 0.3814 (6) −0.1145 (3) 0.8017 (4) 0.0367 (7) 3.0000 Annulus

loop_ _atom_site_annulus_label _atom_site_uiso _atom_site_radius _atom_site_azimuth _atom_site_declination H70 0.0367 (7) 1.030 (3) 0.3631 − 0.6685

The method is described in Chernychev, V. V., Zhukov, S. G., Yatsenko, A. V., Aslanov, L. A., & Schenk, H. (1994). Acta Cryst. A50, 601–605.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Br10.25176 (18)0.10628 (8)0.79765 (14)0.0200
Br20.35686 (19)0.20714 (8)0.45319 (16)0.0213
C10.24192 (16)0.04846 (7)0.60343 (13)0.0138
C20.29857 (16)0.04407 (7)0.60792 (13)0.0144
C30.28815 (15)0.08122 (7)0.45987 (13)0.0137
C40.22875 (16)0.03118 (7)0.31532 (13)0.0140
C50.17519 (17)0.06019 (8)0.32091 (14)0.0155
C60.17920 (16)0.10202 (7)0.46267 (13)0.0145
C70.3654 (2)0.09973 (9)0.76144 (15)0.0242
C80.21915 (18)0.07235 (8)0.15812 (15)0.0197
C90.11843 (19)0.20080 (8)0.46015 (16)0.0213
H510.1272 (5)0.1009 (2)0.2092 (3)0.0338
H810.1730 (6)0.0211 (2)0.0610 (4)0.0469
H820.3555 (5)0.0985 (3)0.1678 (4)0.0430
H830.1230 (6)0.1307 (3)0.1227 (5)0.0460
H910.0695 (7)0.2289 (2)0.3375 (5)0.0509
H920.2348 (5)0.2436 (2)0.5385 (5)0.0467
H930.0056 (5)0.2073 (2)0.5043 (5)0.0446
H700.3814 (6)0.1145 (3)0.8017 (4)0.0367 (7)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.0210 (5)0.0239 (5)0.0160 (4)0.0048 (4)0.0083 (4)0.0078 (4)
Br20.0273 (6)0.0119 (4)0.0296 (6)0.0035 (4)0.0162 (5)0.0020 (4)
C10.0155 (5)0.0133 (4)0.0131 (5)0.0019 (3)0.0060 (4)0.0011 (3)
C20.0164 (5)0.0130 (4)0.0125 (5)0.0000 (4)0.0041 (4)0.0020 (3)
C30.0149 (5)0.0113 (4)0.0152 (5)0.0004 (3)0.0063 (4)0.0008 (3)
C40.0154 (5)0.0140 (4)0.0128 (4)0.0001 (4)0.0057 (4)0.0004 (3)
C50.0193 (5)0.0134 (4)0.0146 (5)0.0018 (4)0.0074 (4)0.0018 (4)
C60.0174 (5)0.0109 (4)0.0160 (5)0.0012 (4)0.0075 (4)0.0006 (4)
C70.0307 (7)0.0231 (6)0.0161 (5)0.0025 (5)0.0062 (5)0.0060 (4)
C80.0223 (6)0.0222 (5)0.0158 (5)0.0004 (4)0.0086 (5)0.0034 (4)
C90.0268 (6)0.0130 (5)0.0276 (6)0.0040 (4)0.0143 (5)0.0011 (4)
H510.0473 (16)0.0311 (12)0.0225 (11)0.0095 (11)0.0130 (11)0.009 (1)
H810.071 (2)0.0443 (16)0.0243 (12)0.0140 (16)0.0177 (14)0.0068 (12)
H820.0353 (15)0.0579 (18)0.0419 (15)0.0111 (14)0.0217 (13)0.0064 (14)
H830.0519 (19)0.0474 (18)0.0426 (16)0.0195 (15)0.0227 (15)0.0216 (13)
H910.079 (3)0.0336 (15)0.0438 (17)0.0177 (15)0.0276 (18)0.0137 (13)
H920.0425 (17)0.0275 (13)0.066 (2)0.0053 (12)0.0168 (16)0.0128 (14)
H930.0439 (16)0.0347 (13)0.069 (2)0.0103 (12)0.0372 (17)0.0033 (14)
H700.0367 (7)1.030 (3)0.36310.00000.00000.6685
Geometric parameters (Å, º) top
Br1—C11.898 (2)C5—H511.091 (3)
Br2—C31.904 (4)C6—C91.501 (3)
C1—C21.403 (3)C7—H700.394 (3)
C1—C61.392 (2)C8—H811.089 (3)
C2—C31.399 (2)C8—H821.090 (3)
C2—C71.497 (2)C8—H831.086 (4)
C3—C41.392 (2)C9—H911.088 (4)
C4—C51.391 (3)C9—H921.091 (4)
C4—C81.498 (2)C9—H931.091 (3)
C5—C61.391 (2)
Br1···H82i2.928 (5)C4···C1i3.871 (5)
Br1···H81ii3.224 (5)C4···C7i3.941 (4)
Br1···H83iii3.256 (5)C4···C1iii3.980 (5)
Br1···H91iv3.339 (6)C4···H70i4.127 (6)
Br1···H93iv3.420 (6)C4···H91vii4.239 (7)
Br1···H70v3.597 (5)C4···C4i4.299 (5)
Br1···C4iii3.612 (5)C4···C6i4.339 (5)
Br1···Br2vi3.791 (5)C4···C6iii4.443 (4)
Br1···C9iv3.835 (5)C4···H83xi4.457 (6)
Br1···C8iii3.838 (5)C5···H81xi3.469 (5)
Br1···C5iii3.882 (5)C5···C3i3.845 (5)
Br1···C7v3.896 (4)C5···H83xi3.862 (6)
Br1···C3iii3.916 (5)C5···C2i3.867 (5)
Br1···C8i3.978 (6)C5···C1iii3.871 (4)
Br1···H92iv4.124 (6)C5···Br1iii3.882 (5)
Br1···H81iii4.132 (6)C5···C7i3.933 (5)
Br1···H51ii4.142 (5)C5···C2iii3.955 (5)
Br1···H51iii4.171 (6)C5···C7iii3.988 (6)
Br1···H70vi4.175 (9)C5···Br2i3.996 (4)
Br1···C8ii4.208 (5)C5···H70i4.055 (6)
Br1···H82ii4.273 (6)C5···H70iii4.077 (7)
Br1···H81i4.298 (7)C5···Br2xii4.110 (6)
Br1···C7vi4.336 (9)C5···C8xi4.177 (4)
Br1···C6iii4.419 (5)C5···H92xiii4.393 (6)
Br1···C2iii4.472 (4)C6···C2iii3.591 (5)
Br2···H93iii2.966 (5)C6···Br2i3.689 (5)
Br2···H91vii3.008 (5)C6···C1iii3.763 (5)
Br2···H83viii3.097 (5)C6···H82i3.817 (5)
Br2···H51vii3.155 (6)C6···C7iii3.891 (5)
Br2···H92i3.168 (6)C6···C3i3.907 (6)
Br2···C6i3.689 (5)C6···C3iii3.940 (5)
Br2···Br1ix3.791 (5)C6···H70iii4.048 (6)
Br2···C9i3.819 (6)C6···C6iii4.270 (5)
Br2···C9vii3.994 (4)C6···H91iv4.290 (5)
Br2···C5i3.996 (4)C6···H83xii4.331 (8)
Br2···C9iii4.034 (5)C6···C4i4.339 (5)
Br2···C1i4.041 (5)C6···C2i4.396 (5)
Br2···H91i4.095 (7)C6···Br1iii4.419 (5)
Br2···C5vii4.110 (6)C6···C4iii4.443 (4)
Br2···C8viii4.166 (6)C6···H82xii4.465 (9)
Br2···H92vii4.223 (7)C7···H92ix3.160 (5)
Br2···H51i4.239 (5)C7···H93iii3.311 (5)
Br2···H70x4.254 (6)C7···H93ix3.396 (6)
Br2···H91iii4.381 (6)C7···H82i3.493 (7)
Br2···C7x4.480 (5)C7···H91iii3.639 (6)
C1···H82i3.069 (5)C7···H82ii3.655 (5)
C1···C1iii3.737 (5)C7···H81ii3.705 (5)
C1···C6iii3.763 (5)C7···H81i3.724 (6)
C1···C2iii3.854 (5)C7···C9iii3.776 (5)
C1···C5iii3.871 (4)C7···C9ix3.776 (5)
C1···C4i3.871 (5)C7···H51i3.823 (6)
C1···C8i3.883 (5)C7···C6iii3.891 (5)
C1···C3i3.911 (5)C7···Br1v3.896 (4)
C1···C3iii3.936 (5)C7···C8i3.899 (5)
C1···C4iii3.980 (5)C7···H51iii3.913 (6)
C1···Br2i4.041 (5)C7···C5i3.933 (5)
C1···H93iii4.101 (8)C7···C4i3.941 (4)
C1···H91iv4.125 (6)C7···C5iii3.988 (6)
C1···H81i4.360 (6)C7···C8ii4.130 (4)
C1···H51iii4.391 (5)C7···H91ix4.218 (6)
C1···H81ii4.432 (6)C7···H83ii4.333 (5)
C1···C9iii4.452 (7)C7···Br1ix4.336 (9)
C2···H93iii3.203 (6)C7···Br2viii4.480 (5)
C2···H82i3.352 (5)C8···H81xi3.196 (5)
C2···C6iii3.591 (5)C8···H92vii3.282 (6)
C2···C4i3.609 (5)C8···H91vii3.297 (7)
C2···C9iii3.788 (5)C8···H51xi3.354 (4)
C2···C1iii3.854 (5)C8···C9vii3.804 (6)
C2···C5i3.867 (5)C8···Br1iii3.838 (5)
C2···C8i3.874 (4)C8···C2i3.874 (4)
C2···C3i3.915 (4)C8···C1i3.883 (5)
C2···C5iii3.955 (5)C8···H70xiv3.891 (5)
C2···H91iii4.066 (6)C8···C7i3.899 (5)
C2···H81i4.109 (6)C8···Br1i3.978 (6)
C2···H51i4.167 (6)C8···H70i4.010 (6)
C2···H51iii4.279 (5)C8···C8xi4.045 (4)
C2···C6i4.396 (5)C8···H83xi4.090 (7)
C2···C2i4.434 (4)C8···C7xiv4.130 (4)
C2···C2iii4.437 (6)C8···Br2x4.166 (6)
C2···Br1iii4.472 (4)C8···C5xi4.177 (4)
C2···H92ix4.480 (6)C8···Br1xiv4.208 (5)
C3···H93iii3.021 (5)C8···H93vii4.378 (6)
C3···C4i3.842 (4)C8···H93iii4.466 (5)
C3···C5i3.845 (5)C9···H82xii3.153 (7)
C3···C3i3.861 (5)C9···H83xii3.408 (6)
C3···C9iii3.885 (4)C9···H70vi3.412 (6)
C3···C6i3.907 (6)C9···C7iii3.776 (5)
C3···C1i3.911 (5)C9···C7vi3.776 (5)
C3···C2i3.915 (4)C9···C2iii3.788 (5)
C3···Br1iii3.916 (5)C9···C8xii3.804 (6)
C3···C1iii3.936 (5)C9···Br2i3.819 (6)
C3···C6iii3.940 (5)C9···Br1xiii3.835 (5)
C3···H91vii4.248 (6)C9···H70iii3.859 (6)
C3···H82i4.273 (6)C9···H92xiii3.860 (5)
C3···H51i4.337 (6)C9···C3iii3.885 (4)
C3···H92i4.363 (6)C9···H91iv3.922 (6)
C3···H91iii4.397 (6)C9···Br2xii3.994 (4)
C4···C2i3.609 (5)C9···Br2iii4.034 (5)
C4···Br1iii3.612 (5)C9···H81xii4.363 (8)
C4···H81xi3.656 (5)C9···H82i4.384 (5)
C4···H93iii3.822 (5)C9···C1iii4.452 (7)
C4···C3i3.842 (4)
Br1—C1—C2119.50 (14)C1—C6—C9122.69 (15)
Br1—C1—C6117.04 (14)C5—C6—C9120.25 (14)
C2—C1—C6123.5 (1)C2—C7—H70178.2 (7)
C1—C2—C3115.9 (1)C4—C8—H81110.8 (2)
C1—C2—C7122.1 (1)C4—C8—H82111.7 (2)
C3—C2—C7122.01 (14)H81—C8—H82107.8 (3)
Br2—C3—C2118.84 (9)C4—C8—H83111.1 (2)
Br2—C3—C4117.63 (9)H81—C8—H83108.8 (4)
C2—C3—C4123.53 (14)H82—C8—H83106.4 (3)
C3—C4—C5117.14 (16)C6—C9—H91110.8 (2)
C3—C4—C8122.62 (15)C6—C9—H92110.8 (2)
C5—C4—C8120.2 (1)H91—C9—H92108.1 (3)
C4—C5—C6122.9 (1)C6—C9—H93111.4 (2)
C4—C5—H51118.69 (18)H91—C9—H93108.5 (3)
C6—C5—H51118.4 (2)H92—C9—H93107.1 (3)
C1—C6—C5117.06 (16)
Symmetry codes: (i) x+1, y, z+1; (ii) x, y, z+1; (iii) x, y, z+1; (iv) x+1/2, y+1/2, z+1/2; (v) x+1, y, z+2; (vi) x+1/2, y+1/2, z+3/2; (vii) x+1/2, y1/2, z+1/2; (viii) x+1/2, y1/2, z+1/2; (ix) x+1/2, y1/2, z+3/2; (x) x1/2, y1/2, z1/2; (xi) x, y, z; (xii) x+1/2, y+1/2, z+1/2; (xiii) x1/2, y+1/2, z1/2; (xiv) x, y, z1.

Experimental details

(14K)(120K)
Crystal data
Chemical formulaC9H10Br2C9H10Br2
Mr277.99277.99
Crystal system, space groupMonoclinic, P21/nMonoclinic, P21/n
Temperature (K)14120
a, b, c (Å)7.691 (13), 14.41 (2), 8.909 (11)7.721 (14), 14.46 (3), 8.924 (17)
β (°) 113.13 (2) 112.87 (2)
V3)908 (2)918 (3)
Z44
Radiation typeNeutron, λ = 0.83080 ÅNeutron, λ = 0.83080 Å
µ (mm1)0.390.39
Crystal size (mm)3.5 × 3.0 × 3.03.5 × 3.0 × 3.0
Data collection
DiffractometerOrphée reactor (Saclay, France): 5C2 four-circle
diffractometer
Orphée reactor (Saclay, France): 5C2 four-circle
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 3σ(I)] reflections
3875, 2998, 2347 3242, 2547, 1490
Rint0.0170.017
(sin θ/λ)max1)0.7330.691
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.026, 0.023, 1.16 0.032, 0.024, 1.06
No. of reflections23471490
No. of parameters224169
No. of restraints300
H-atom treatmentAll H-atom parameters refinedAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.65, 0.971.42, 1.17

Computer programs: PRON (Scherf, 1998), CRYSTALS (Watkin et al., 1999a), CAMERON (Watkin, Prout & Pearce, 1999b), CRYSTALS I (Watkin et al., 1999a).

Selected geometric parameters (Å, º) for (14K) top
Br1—C11.9037 (19)C7—H711.073 (2)
Br2—C31.906 (3)C7—H721.0801 (18)
C1—C21.4025 (19)C7—H731.092 (2)
C1—C61.3967 (14)C7—H741.090 (2)
C2—C31.4038 (15)C7—H751.085 (2)
C2—C71.4993 (15)C7—H761.080 (2)
C3—C41.3962 (14)C8—H811.0890 (17)
C4—C51.3943 (19)C8—H821.0921 (19)
C4—C81.5008 (16)C8—H831.0938 (18)
C5—C61.3939 (15)C9—H911.0860 (18)
C5—H511.0911 (16)C9—H921.0909 (17)
C6—C91.500 (2)C9—H931.0912 (18)
Br1—C1—C2119.34 (9)C2—C7—H73109.48 (14)
Br1—C1—C6117.06 (9)H71—C7—H73108.0 (2)
C2—C1—C6123.60 (5)H72—C7—H73106.7 (2)
C1—C2—C3115.77 (5)C2—C7—H74108.5 (3)
C1—C2—C7121.65 (5)C2—C7—H75111.0 (3)
C3—C2—C7122.58 (9)H74—C7—H75107.4 (2)
Br2—C3—C2119.02 (4)C2—C7—H76114.4 (3)
Br2—C3—C4117.39 (4)H74—C7—H76107.5 (2)
C2—C3—C4123.59 (9)H75—C7—H76107.8 (2)
C3—C4—C5117.08 (11)C4—C8—H81110.75 (11)
C3—C4—C8122.7 (1)C4—C8—H82111.55 (11)
C5—C4—C8120.22 (5)H81—C8—H82108.10 (15)
C4—C5—C6122.87 (5)C4—C8—H83110.69 (11)
C4—C5—H51118.53 (8)H81—C8—H83108.84 (16)
C6—C5—H51118.60 (11)H82—C8—H83106.77 (14)
C1—C6—C5117.09 (11)C6—C9—H91110.79 (9)
C1—C6—C9122.6 (1)C6—C9—H92110.8 (1)
C5—C6—C9120.33 (9)H91—C9—H92108.30 (15)
C2—C7—H71113.56 (17)C6—C9—H93111.69 (12)
C2—C7—H72110.55 (16)H91—C9—H93108.44 (14)
H71—C7—H72108.28 (17)H92—C9—H93106.67 (17)
Selected geometric parameters (Å, º) for (120K) top
Br1—C11.898 (2)C5—C61.391 (2)
Br2—C31.904 (4)C5—H511.091 (3)
C1—C21.403 (3)C6—C91.501 (3)
C1—C61.392 (2)C8—H811.089 (3)
C2—C31.399 (2)C8—H821.090 (3)
C2—C71.497 (2)C8—H831.086 (4)
C3—C41.392 (2)C9—H911.088 (4)
C4—C51.391 (3)C9—H921.091 (4)
C4—C81.498 (2)C9—H931.091 (3)
Br1—C1—C2119.50 (14)C1—C6—C5117.06 (16)
Br1—C1—C6117.04 (14)C1—C6—C9122.69 (15)
C2—C1—C6123.5 (1)C5—C6—C9120.25 (14)
C1—C2—C3115.9 (1)C4—C8—H81110.8 (2)
C1—C2—C7122.1 (1)C4—C8—H82111.7 (2)
C3—C2—C7122.01 (14)H81—C8—H82107.8 (3)
Br2—C3—C2118.84 (9)C4—C8—H83111.1 (2)
Br2—C3—C4117.63 (9)H81—C8—H83108.8 (4)
C2—C3—C4123.53 (14)H82—C8—H83106.4 (3)
C3—C4—C5117.14 (16)C6—C9—H91110.8 (2)
C3—C4—C8122.62 (15)C6—C9—H92110.8 (2)
C5—C4—C8120.2 (1)H91—C9—H92108.1 (3)
C4—C5—C6122.9 (1)C6—C9—H93111.4 (2)
C4—C5—H51118.69 (18)H91—C9—H93108.5 (3)
C6—C5—H51118.4 (2)H92—C9—H93107.1 (3)
 

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