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The title compound, C12H16BrO2, is an inter­esting case of a simple organic mol­ecule making use of five different types of intra- and inter­molecular inter­actions (viz. conventional and nonconventional hydrogen bonds, and π–π, Br...Br and Br...O contacts), all of them relevant in the mol­ecular and crystal structure geometry. The mol­ecules are strictly planar, with an intra­molecular O—H...O hydrogen bond, and associate into two-dimensional structures parallel to (\overline{2}01) through two different types of halogen bonding. The planar structures, in turn, stack parallel to each other inter­linked by C—H...π and π–π contacts. Also discussed are the relevant structural features leading to the rather low melting point of the compound.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270109013286/fg3087sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270109013286/fg3087Isup2.hkl
Contains datablock I

CCDC reference: 735131

Comment top

Non-covalent interactions have been the subject of both theoretical and experimental studies for many years and they continue to receive increasing attention. Hydrogen bonding was certainly the first such interaction to be extensively studied, followed by ππ and C—H···π interactions. The so-called `halogen bond', where the main feature is a highly polarized halogen species (Desiraju & Parthasarathy, 1989; Metrangolo et al. 2007; Metrangolo, Meyer et al. 2008), has also been known for decades, but was `rediscovered' only recently. In fact, the number of studies dealing with halogen bonds has increased rapidly in the last five years (Metrangolo & Resnati, 2008). In spite of some controversies about the fundamental nature of some of these non-covalent interactions (Palusiak & Grabowski, 2008; Rissanen, 2008) and the lack of a deep understanding of some of them (Sinnokrot & Sherrill, 2006; Zhang et al., 2007), they are all currently and successfully used as tools in crystal engineering, in biomimetic processes involving molecular recognition and in the molecular design of advanced materials, including magnetic materials and liquid crystals.

The relative strengths of these interactions are neither predictable nor understandable in a straightforward manner. Several authors have tried to establish, for a given compound (or series of compounds), which of these interactions is ultimately responsible for the resulting structure (Gavezzotti 2008). In other cases, the simultaneous presence of different types of non-covalent interactions has been viewed as a competition process (Csoregh et al., 2001), and the underlying question was which of the interactions would prevail over the others, thus determining the supramolecular arrangement.

Among the interactions we shall deal with in the present paper, the least common are those of the C—X···O and C—X···X—C types (X is a halogen). The main aspects of the former are quite close to those of a conventional hydrogen bond, and accordingly its most conspicuous geometric characteristics are a rather large C—X···O angle (>150°) and an X···O distance shorter than the sum of the van der Waals radii. The second type, instead, is rather more complex from a descriptive point of view, but the main aspects could be summarized as follows. If θ1 is the larger of the two C—X···X angles and θ2 the smaller, then two kinds of C—X···X—C interactions can be envisaged (Desiraju & Parthasarathy, 1989): the (so-called) I1 interactions have θ1 = θ2, while those of type I2 have θ1 ~180° and θ2 ~90°. In both cases, the X···X distance is shorter than the sum of the van der Waals radii.

The title compound, (I), presents an interesting case of a simple organic molecule displaying a range of different types of intra- and intermolecular interactions, viz. Br—Br and Br—O contacts, conventional and non-conventional hydrogen bonds, ππ interactions and extremely weak (though non-negligible) van der Waals interactions maximized by the parallel array of hydrophobic alkyl chains. We have found all of them to be relevant to a greater or lesser degree for the molecular and crystal structure geometry of (I).

Fig. 1 shows a molecular view of (I), displaying the labelling scheme and its intermolecular interactions (to be discussed below). Bond distances and angles are unexceptional and comparable with the recently reported related structures 1,2-dibromo-4,5-dimethoxybenzene, (II), and 1,2-diiodo-4,5-dimethoxybenzene (Cukiernik et al., 2008). The most conspicuous characteristic of the molecule is its overall planarity (average deviation from the least-squares plane = 0.032 Å, maximum deviation = 0.092 Å for atom C7), a property enhanced by the intramolecular O2—H2A···O1 bond (Table 1 and Fig. 1). This least-squares plane almost contains a centre of symmetry (0.124 Å away from the plane), which in turn generates a planar dimer through a head-to-head C—Br···.Br—C type I2 interaction (Table 3 and Fig. 1). The Br···Br distance [3.676 (1) Å] puts this interaction rather on the weak side; a survey of similar contacts in the Cambridge Structural Database (CSD; 2009 Version; Allen, 2002) showed 511 cases reported, covering a range from 3.30 up to 3.70 Å, with a median (maximum occurrence) at 3.62 Å.

In addition, the dimers are laterally linked to each other through a C—Br···O bond (Table 4 and Fig. 1) to which a similar analysis can be applied. A CSD search provided some 1400 cases covering (with a significant population) the range 2.90–3.37 Å, with a median of 3.20 Å, a value significantly shorter than the Br···O distance in (I) [3.28 (1) Å]. The interaction serves to form planar strips two molecules wide, with the hydrophobic organic tail oriented outwards in a comb-like structure. These combs interdigitate in a classical packing array of parallel hydrophobic alkyl chains, thus maximizing the van der Waals interactions, with minimum C···C approach distances in the range 3.86 (1)–3.90 (1) Å.

The outcome of these interactions is the formation of planar two-dimensional structures parallel to (201) (Fig. 2). These structures in turn interact with their nearest neighbours, 3.60 (5) Å apart, through two different types of interactions, also shown in Fig. 1, namely a C—H···π bond (Table 1 and upper portion of Fig. 1) and a ππ contact (Table 2 and lower portion of Fig. 1).

Thus, the crystal structure of (I) is the result of an intricate balance between a diversity of interactions covering a vast range, from medium strength (halogen bonding) down to weak (interchain van der Waals contacts).

Although all these interactions seem to provide the stability of (I), the geometric requirements of some of them tend to act as restraints for the others to reach more optimized geometries. For example, closer Br···Br or Br···O approaches would conflict with the setting up of proper ππ or aliphatic chain interactions. The resulting compromise renders the structure stable, but not as stable as might be anticipated from the presence of potentially strong C—Br···Br—C and C—Br···O interactions.

This relative weakness in (I) is evidenced in the rather low melting point of 326 K, well below those found in structurally analogous compounds with a similar display of non-bonding interactions, e.g. 1,2-dibromo-4,5-dimethoxybenzene (Cukiernik et al., 2008), (II), which has a melting point in the range 362–364 K. Since the main difference between these two molecular structures lies in the lateral chain, present in (I) but lacking in (II) (see scheme), it is tempting to look in this direction to find out the reasons for such a weakening. [The hydrogen bonding in (I) is intramolecular, so it can be disregarded from the present analysis.]

From a structural point of view, the presence of this aliphatic chain favours a head-to-head arrangement with interdigitated tails. From an energetic point of view, the contributions of the aliphatic chains to the total melting enthalpy can be roughly estimated as 22–25 kJ mol-1, taking 3.7–4.1 kJ mol-1 as the melting enthalpy of one mole of CH2 or CH3 groups (Weast, 1986; Seurin et al., 1981). This value accounts for ca two thirds of the measured melting enthalpy (37 kJ mol-1; see Experimental section), thus supporting our previous suggestion. It seems that conformational freedom at the aliphatic chain level allows the system to override the stronger interactions, thus melting at a moderate temperature. This kind of distribution analysis of the melting enthalpy is often found in the field of molecular liquid crystals (LC), materials structurally related to (I) in the sense that they also usually present `localized' (stronger) and van der Waals (weaker) interactions in synergic cooperation. Indeed, the molecular description of several types of LC phases involves molten aliphatic chains and more or less oriented interacting cores. The presence in (I) of a halogen-bonding-based `extended core' might in principle induce some LC character, even if, from its molecular structure, (I) is not expected to exhibit LC behaviour as its aromatic part is not long enough. As a matter of fact, we have not found any evidence of LC phases in (I), a result that can be ascribed to the previously discussed weakness of the C—Br···Br—C and C—Br···O interactions. In particular, the few LC based on halogen bonding known to date are based on one of the strongest types of halogen bond, involving N atoms as donors and I atoms bound to electron-withdrawing groups as acceptors (Bruce et al., 2008).

Finally, the influence of chain length on melting point has been extensively studied in LC (Demus, 1998). Short-chain compounds usually melt at higher temperatures, since in these structures the localized interactions prevail. On increasing the chain length, it is often observed that the m.p. decreases down to a certain limit, rising again afterwards. The accepted explanation for this behaviour is based on the structure-disturbing effect associated with middle-length aliphatic chains, in accordance with the ideas herein suggested for (I).

Experimental top

2-(Hexyloxy)phenol was synthesized under typical conditions for Williamson's etherification following published procedures (Wan et al., 2003), with 38% yield. The dibromo compound, (I), was prepared by direct halogenation of 2-(hexyloxy)phenol using Br2 in a manner exactly analogous to that described in the synthesis of 1,2-dibromo-4,5-dimethoxybenzene (Cukiernik et al., 2008); full experimental details are in the archived CIF.

Refinement top

The H atom attached to atom O2 was found in a difference Fourier map, further idealized (O—H = 0.82 Å) and finally allowed to ride. H atoms attached to C atoms were placed in calculated positions [C—H = 0.93 (aromatic) or 0.96 Å (methyl)] and allowed to ride; methyl groups were allowed to rotate as well. Displacement parameters were taken as Uiso(H) = xUeq(parent), where x is 1.2 (aromatic) or 1.5 (methyl, O—H).

Computing details top

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988); cell refinement: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988); data reduction: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Figures top
[Figure 1] Fig. 1. A molecular view of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the XX% probability level [Please complete] and H atoms have been omitted for clarity. Dashed lines indicate the intra- and intermolecular interactions present. Heavy lines denote molecules in the reference plane and light lines denote molecules in the planes above and below the former. [Symmetry codes: (i) 1 - x, 1 - y, 1 - z; (ii) 2 - x, 1 - y, 1 - z; (iii) 2 - x, 1 - y, 2 - z; (iv) x, 1 + y, z.]
[Figure 2] Fig. 2. A packing diagram for (I), showing the (201) plane formed by the interdigitated strips. [Symmetry codes: (iii) 2 - x, 1 - y, 2 - z; (iv) x, 1 + y, z.]
4,5-dibromo-2-hexyloxyphenol top
Crystal data top
C12H16Br2O2Z = 2
Mr = 352.07F(000) = 348
Triclinic, P1Dx = 1.736 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 8.863 (4) ÅCell parameters from 25 reflections
b = 9.140 (4) Åθ = 7.5–12.5°
c = 10.148 (6) ŵ = 6.00 mm1
α = 65.70 (4)°T = 295 K
β = 79.43 (5)°Block, colourless
γ = 64.03 (3)°0.22 × 0.14 × 0.10 mm
V = 673.6 (6) Å3
Data collection top
Rigaku AFC-6S
diffractometer
1775 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.053
Graphite monochromatorθmax = 26.0°, θmin = 2.2°
ω/2θ scansh = 1010
Absorption correction: ψ scan
(North et al., 1968)
k = 911
Tmin = 0.40, Tmax = 0.55l = 112
2800 measured reflections3 standard reflections every 150 reflections
2641 independent reflections intensity decay: <2%
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.063Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.183H-atom parameters constrained
S = 0.97 w = 1/[σ2(Fo2) + (0.1433P)2]
where P = (Fo2 + 2Fc2)/3
2641 reflections(Δ/σ)max < 0.001
146 parametersΔρmax = 1.53 e Å3
0 restraintsΔρmin = 1.48 e Å3
Crystal data top
C12H16Br2O2γ = 64.03 (3)°
Mr = 352.07V = 673.6 (6) Å3
Triclinic, P1Z = 2
a = 8.863 (4) ÅMo Kα radiation
b = 9.140 (4) ŵ = 6.00 mm1
c = 10.148 (6) ÅT = 295 K
α = 65.70 (4)°0.22 × 0.14 × 0.10 mm
β = 79.43 (5)°
Data collection top
Rigaku AFC-6S
diffractometer
1775 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.053
Tmin = 0.40, Tmax = 0.553 standard reflections every 150 reflections
2800 measured reflections intensity decay: <2%
2641 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0630 restraints
wR(F2) = 0.183H-atom parameters constrained
S = 0.97Δρmax = 1.53 e Å3
2641 reflectionsΔρmin = 1.48 e Å3
146 parameters
Special details top

Experimental. 4,5-Dibromo-2-(hexyloxy)phenol: In a two-necked 250 ml flask equipped with a pressure-compensated funnel were placed 2-(hexyloxy)phenol (26.4 g) and dicloromethane (85 ml). The flask was placed in an ice bath, and while the mixtures cooled to 278 K a vessel bubbler, with an Na2CO3 solution was placed in the remaining neck, to neutralize the HBr vapours generated. A solution of Br2 (8 ml) in CH2Cl2 (25 ml) was loaded into the addition funnel and added dropwise in continuous stirring over a period of 90 min, giving a red solution. The ice bath was removed and the solution stirred until it remained colourless. Water (50 ml) was added to the mixture, then, the contents of the flask were poured carefully into a separation funnel. The organic phase was washed with NaHCO3(ss) and water again, dried over NaSO4 and evaporated. The crude product was purified by vacuum distillation. The undistilled product was passed quickly through a fritted disc funnel with a short column of silica, eluting with a mixture of dicloromethane and cyclohexane. The solution was evaporated and the resulting solid was recrystallized from heptane, yielding 1.7 g (3.5%) of colourless solid. Crystals were obtained by slow evaporation of heptane. Elemental analysis found (calculated) for C12H16Br2O2: C 41.2% (40.94%), H 4.6% (4.58%). 1H NMR δ 7.17 and 7.04 (2H, Ar—H), 5.59 (s, 1H, OH)4.00 (t, 2H, -OCH2-), 1.81 (m, 2H, -OCH2CH2-),1.44 (m, 4H, -CH2CH2CH3), 0.91 (t, 3H, -CH3). 13C NMR δ 146.23, 146.03, 119.37, 116.48, 115.58, 114.06, 69.88, 31.79, 29.29,25.91, 22.89, 14.33. m.p. measured by Fisher–Jones method: 326 K, measured by differential scanning calorimetry (Shimadzu DSC-50): 326 K (onset), Δ H = 37 kJ mol-1.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Br10.86665 (9)0.71188 (9)0.70536 (7)0.0617 (3)
Br20.99851 (9)0.30262 (10)0.96620 (7)0.0620 (3)
O10.7001 (6)0.4391 (6)0.4159 (5)0.0575 (11)
O20.8258 (8)0.1149 (7)0.6185 (6)0.0779 (17)
H2A0.77540.16620.54120.093*
C10.8536 (8)0.5181 (8)0.6859 (7)0.0455 (13)
C20.7807 (8)0.5571 (8)0.5567 (6)0.0477 (14)
H20.74100.67070.48760.057*
C30.7697 (7)0.4234 (8)0.5355 (6)0.0467 (13)
C40.8338 (8)0.2532 (8)0.6392 (7)0.0497 (14)
C50.8990 (8)0.2190 (8)0.7652 (7)0.0517 (15)
H50.93720.10590.83520.062*
C60.9080 (8)0.3531 (9)0.7883 (7)0.0508 (15)
C70.6361 (9)0.6096 (9)0.3043 (7)0.0527 (15)
H7A0.72210.65560.27220.063*
H7B0.54110.68950.34000.063*
C80.5822 (8)0.5918 (9)0.1799 (7)0.0531 (15)
H8A0.67800.51040.14620.064*
H8B0.49780.54360.21410.064*
C90.5112 (9)0.7668 (9)0.0546 (7)0.0531 (15)
H9A0.59660.81350.01920.064*
H9B0.41740.84900.08920.064*
C100.4520 (8)0.7520 (9)0.0704 (7)0.0517 (15)
H10A0.54570.66820.10350.062*
H10B0.36610.70600.03460.062*
C110.3837 (10)0.9201 (9)0.1953 (8)0.0669 (19)
H11A0.46950.96620.23140.080*
H11B0.28981.00400.16240.080*
C120.3252 (12)0.9040 (11)0.3187 (9)0.085 (3)
H12A0.24800.84830.28220.127*
H12B0.42030.83480.36130.127*
H12C0.27051.01880.39050.127*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.0895 (5)0.0617 (5)0.0459 (4)0.0372 (4)0.0083 (3)0.0207 (3)
Br20.0781 (5)0.0738 (5)0.0360 (4)0.0333 (4)0.0100 (3)0.0153 (3)
O10.084 (3)0.052 (2)0.040 (3)0.029 (2)0.018 (2)0.013 (2)
O20.135 (5)0.053 (3)0.053 (3)0.041 (3)0.027 (3)0.012 (2)
C10.061 (3)0.052 (3)0.034 (3)0.030 (3)0.004 (3)0.020 (3)
C20.065 (4)0.049 (3)0.027 (3)0.026 (3)0.003 (2)0.007 (2)
C30.053 (3)0.053 (3)0.033 (3)0.016 (3)0.004 (2)0.020 (3)
C40.058 (3)0.044 (3)0.052 (4)0.017 (3)0.006 (3)0.023 (3)
C50.057 (3)0.052 (4)0.039 (3)0.018 (3)0.003 (3)0.013 (3)
C60.056 (3)0.060 (4)0.036 (3)0.024 (3)0.001 (3)0.016 (3)
C70.069 (4)0.065 (4)0.034 (3)0.034 (3)0.004 (3)0.018 (3)
C80.067 (4)0.062 (4)0.035 (3)0.027 (3)0.006 (3)0.019 (3)
C90.068 (4)0.057 (4)0.039 (3)0.025 (3)0.008 (3)0.019 (3)
C100.068 (4)0.054 (4)0.035 (3)0.022 (3)0.004 (3)0.020 (3)
C110.088 (5)0.057 (4)0.047 (4)0.019 (4)0.019 (3)0.013 (3)
C120.135 (8)0.063 (5)0.054 (5)0.033 (5)0.030 (5)0.015 (4)
Geometric parameters (Å, º) top
Br1—C11.915 (6)C7—H7B0.9700
Br2—C61.907 (6)C8—C91.520 (9)
O1—C31.389 (7)C8—H8A0.9700
O1—C71.429 (8)C8—H8B0.9700
O2—C41.396 (7)C9—C101.534 (8)
O2—H2A0.8201C9—H9A0.9700
C1—C61.357 (9)C9—H9B0.9700
C1—C21.410 (8)C10—C111.482 (9)
C2—C31.370 (9)C10—H10A0.9700
C2—H20.9300C10—H10B0.9700
C3—C41.396 (9)C11—C121.522 (9)
C4—C51.361 (9)C11—H11A0.9700
C5—C61.376 (9)C11—H11B0.9700
C5—H50.9300C12—H12A0.9600
C7—C81.519 (8)C12—H12B0.9600
C7—H7A0.9700C12—H12C0.9600
C3—O1—C7117.0 (5)C7—C8—H8A109.2
C4—O2—H2A101.6C9—C8—H8B109.2
C6—C1—C2120.9 (6)C7—C8—H8B109.2
C6—C1—Br1123.6 (5)H8A—C8—H8B107.9
C2—C1—Br1115.5 (4)C8—C9—C10112.7 (5)
C3—C2—C1118.3 (6)C8—C9—H9A109.0
C3—C2—H2120.8C10—C9—H9A109.0
C1—C2—H2120.8C8—C9—H9B109.0
C2—C3—O1125.8 (6)C10—C9—H9B109.0
C2—C3—C4119.8 (5)H9A—C9—H9B107.8
O1—C3—C4114.4 (5)C11—C10—C9114.2 (6)
C5—C4—O2118.4 (6)C11—C10—H10A108.7
C5—C4—C3121.0 (6)C9—C10—H10A108.7
O2—C4—C3120.6 (5)C11—C10—H10B108.7
C4—C5—C6119.5 (6)C9—C10—H10B108.7
C4—C5—H5120.3H10A—C10—H10B107.6
C6—C5—H5120.3C10—C11—C12113.8 (6)
C1—C6—C5120.4 (6)C10—C11—H11A108.8
C1—C6—Br2120.9 (5)C12—C11—H11A108.8
C5—C6—Br2118.8 (5)C10—C11—H11B108.8
O1—C7—C8107.7 (5)C12—C11—H11B108.8
O1—C7—H7A110.2H11A—C11—H11B107.7
C8—C7—H7A110.2C11—C12—H12A109.5
O1—C7—H7B110.2C11—C12—H12B109.5
C8—C7—H7B110.2H12A—C12—H12B109.5
H7A—C7—H7B108.5C11—C12—H12C109.5
C9—C8—C7112.0 (5)H12A—C12—H12C109.5
C9—C8—H8A109.2H12B—C12—H12C109.5
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2A···O10.822.132.688 (7)124
C8—H8B···Cg1i0.962.933.753 (8)143
Symmetry code: (i) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC12H16Br2O2
Mr352.07
Crystal system, space groupTriclinic, P1
Temperature (K)295
a, b, c (Å)8.863 (4), 9.140 (4), 10.148 (6)
α, β, γ (°)65.70 (4), 79.43 (5), 64.03 (3)
V3)673.6 (6)
Z2
Radiation typeMo Kα
µ (mm1)6.00
Crystal size (mm)0.22 × 0.14 × 0.10
Data collection
DiffractometerRigaku AFC-6S
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.40, 0.55
No. of measured, independent and
observed [I > 2σ(I)] reflections
2800, 2641, 1775
Rint0.053
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.063, 0.183, 0.97
No. of reflections2641
No. of parameters146
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.53, 1.48

Computer programs: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2A···O10.822.132.688 (7)124.0
C8—H8B···Cg1i0.962.933.753 (8)143.0
Symmetry code: (i) x+1, y+1, z+1.
ππ interactions (Å, °) for (I) top
Group 1/Group 2CCD (Å)SA (°)IPD (Å)
Cg1/Cg1ii4.373 (5)36.(1)3.60 (1)
Symmetry code: (ii) 2 - x, 1 - y, 1 - z. Notes: Cg1 is the centroid of the C1–C6 ring, CCD is the centre-to-centre distance (distance between ring centroids), SA is the mean slippage angle (angle subtended by the intercentroid vector to the plane normal) and IPD is the mean interplanar distance (distance from one plane to the neighbouring centroid). For details, see Janiak (2000).
C—Br···Br—C interactions (Å, °) for (I) top
C'—Br'···Br''-C''C'—Br'C''—Br''Br'···Br''θ1θ2
C1—Br1···(Br2—C6)iii1.915 (1)1.907 (1)3.676 (1)124.8 (1)170.0 (1)
Symmetry code: (iii) 2 - x, 1 - y, 2 - z. Notes: θ1 = C'—Br'···Br'', the smaller of the two XB angles; θ2 = Br'···Br''—C'', the larger of the two XB angles. Expected values: θ1 ~90° and θ2 ~180° (for I2 type contacts) or θ1 ~θ2 (for I1 type contacts). For details, see Desiraju & Parthasarathy (1989).
C—Br···O interactions (Å, °) for (I) top
C—Br···OC—BrBr···OC—Br···O
C1—Br1···O2iv1.915 (1)3.280 (5)158.4 (2)
Symmetry code: (iv) x, 1 + y, z. For details, see Desiraju & Parthasarathy (1989).
 

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