Structural characteristics of dibromo­borylated benzene derivatives

The crystal structures of five dibromo­benzene derivatives, namely dibromo­boryl­benzene, C₆H₅BBr₂, (I), 1-dibromo­bor­yl-4-(trimethyl­silyl)­benzene, C₉H₁₃BBr₂Si, (II), 4-bromo-1-(di­bromo­boryl)­benzene, C₆H₄BBr₃, (III), dibromo(di­methyl­am­ino)­(phenyl)­borane, C₈H₁₂BBr₂N, (IV), and dibromo­(di­methyl­sulfanyl)­[4-(trimethyl­silyl)­phenyl]­borane, C₁₁H₁₉BBr₂SSi, (V), have been determined. Compounds (I)-(IV) crystallize with one mol­ecule in the asymmetric unit, but the mol­ecule of (V) is located on a crystallographic mirror plane, implying twofold disorder of the central aromatic ring, the S atom and one of the methyl groups bonded to the S atom. In (I), (II) and (III), the B atom is three-coordinated, and in (IV) and (V) it is four-coordinated. The geometric parameters of the -BBr₂ group in these five structures agree well with those of comparable structures retrieved from the Cambridge Structural Database. The C-B and B-Br bond lengths in the mol­ecules with a three-coordinated B atom are significantly shorter than those in the mol­ecules with a four-coordinated B atom. In the compounds with a three-coordinated B atom, the -BBr₂ group tends to be coplanar with the aromatic ring to which it is attached.

S1. Comment

In the past few decades, dihaloboryl-substituted arenes have gained significant importance as starting materials for e.g. aryl(hydro)boranes (Lorbach et al., 2012) and BN addition compounds (Heilmann-Brohl et al., 2011). Both classes of substance feature intriguing optoelectronic behaviour. We present here the crystal structures of a series of dibromoborylated benzene derivatives and a comparison of their molecular structures.

Dibromoborylbenzene, (I) (Fig. 1), features an essentially planar molecule (r.m.s. deviation for all non-H atoms = 0.007 Å) and a dihedral angle of 3.7 (3)° between the –BBr₂ group and the aromatic ring. The packing (Fig. 2) shows pairs of centrosymmetrically related molecules, with the B atom located almost directly over the C atom in the para position of the ring [B1—C4ⁱ = 3.584 (9) Å; symmetry code: (i) -x + 1, -y + 1, -z + 1].

In 1-dibromoboryl-4-(trimethylsilyl)benzene, (II), the para position of the dibromobenzene ring is substituted with a trimethylsilyl residue (Fig. 3). The dihedral angle between the aromatic ring and the –BBr₂ group is 6.4 (3)°. As for (I), the packing (Fig. 4) shows pairs of centrosymmetrically related molecules, which are slightly displaced from one another. The B atom is located over (but with a slight displacement from) the C atom in the ortho position of the ring [B1—C5ⁱ =3.626 (5) Å; symmetry code: (i) -x + 1, -y + 1, -z + 1].

In 4-bromo-1-(dibromoboryl)benzene, (III), a bromine residue is located in the the para position of the dibromobenzene ring (Fig. 5), decreasing the electron density of the C atom to which it is bonded. The dihedral angle between the aromatic ring and the –BBr₂ group is 6.4 (3)°. The packing (Fig. 6) shows intermolecular contacts between the Br atoms in the para position of the ring [Br3···Br3ⁱ = 3.663 Å and Br3···Br3ⁱⁱ = 3.663 (2) Å; symmetry codes: (i) y - 3/4, -x + 3/4, -z - 1/4; (ii) -y + 3/4, x + 3/4, -z - 1/4].

Dibromo(dimethylamino)(phenyl)borane, (IV) (Fig. 7), is the reaction product of (I) with dimethylamine. Whereas the B atom is still located in the plane of the aromatic ring [it deviates by just 0.034 (9) Å from the ring plane], the two Br atoms deviate by -0.976 (9) (Br1) and -0.819 (10) Å (Br2) from the ring plane. The N atom is displaced even further [1.538 (9) Å] from the ring plane in the opposite direction to the Br residues. The crystal packing (Fig. 8) shows that the molecules are connected by N—H···Br hydrogen bonds to form centrosymmetric dimers. It is remarkable that the amino H atom forms two almost equal hydrogen bonds to the two Br atoms of another molecule (Table 1).

Dibromo(dimethylsulfanyl)[4-(trimethylsilyl)phenyl]borane, (V) (Fig. 9), is the reaction product of (II) with dimethyl sulfide. The molecule is located on a crystallographic mirror plane. As a result, the central ring, the S atom and one of the methyl groups bonded to the S atom are disordered over two equally occupied orientations. Due to this disorder, the deviation of the B, Br and S atoms from the ring plane(s) is not discussed.

In order to compare these five structures with similar compounds, a search of the Cambridge Structural Database (CSD, Version 5.33 of November 2011 plus one update; Allen, 2002) was performed for an aromatic ring carrying a –BBr₂ residue. Eight entries were found, namely 4-(dibromoboryl)toluene (AYUHIL), 1,3-bis(dibromoboryl)benzene (AYUHOR), 1,4-bis(dibromoboryl)benzene (AYUHUX), 1,3,5-tris(dibromoboryl)benzene (AYUJAF) and 4,4'-bis(dibromoboryl)biphenyl (AYUJEJ) (Haberecht et al., 2004), dibromo(2,4,6-triisopropylphenyl)borane (EHUBEO) (Olmstead et al., 2003), and dibromo(2,6-dimesitylphenyl)borane (TIZXAB) and dibromo[2,6-bis(2,4,6-triisopropylphenyl)phenyl]borane (TIZXEF) (Grisby & Power, 1996), with a mean C—B bond length of 1.55 (3) Å and a mean B—Br bond length of 1.91 (1) Å. These values agree well with those in (I), (II) and (III) (Table 2).

If the substitutents of the ring in the ortho position with respect to the –BBr₂ group are H atoms, the –BBr₂ group is coplanar with the ring. The dihedral angle between the ring and the –BBr₂ group ranges from 1.8 (AYUJEJ) to 8.8° (AYUJAF). In three of the structures, the ortho substituents are very bulky and force the –BBr₂ group into an almost perpendicular position with respect to the aromatic ring (dihedral angles BBr₂/ring: 87.3° in EHUBEO, 77.5° in TIZXAB and 90.0° in TIZXEF).

A search of the CSD for an aromatic ring carrying a –BBr₂ residue with a four-coordinated B atom revealed only two structures, dibromo(2-dimethylaminomethylphenyl)borane (CEJWUJ; Brown et al., 1998) and bromo(bromo{4-[dibromo(tricyclohexylphosphino)boranyl]phenyl}boranyl-B)- bis(tricyclohexylphosphino)platinum benzene n-hexane solvate (QOMLEK; Braunschweig et al., 2008). The C—B bond lengths of 1.559 (CEJWUJ) and 1.609 Å (QOMLEK), and the B—Br bond lengths (2.019 and 2.020 Å in CEJWUJ, and 2.046 and 2.056 Å in QOMLEK) are in good agreement with those of (IV) and (V) (Table 2). Apart from these distances, the two database structures differ too much from (IV) and (V) for further comparison.

In conclusion, it can be said that the C—B and B—Br bonds are significantly elongated if the number of substituents at the B atom is increased from three to four. Molecules containing a three-coordinated B atom carrying two Br atoms tend to have the –BBr₂ group coplanar with the aromatic ring, as long as no bulky substituents in the ortho position of the aromatic ring prevent coplanarity. The crystal packing of these structures depends on the substitution pattern. Compounds (I) and (II), with electron-rich residues in the position para to the –BBr₂ group, feature a B–π interaction in their crystal structures, whereas no such interaction is observed in the structures of (III), (IV) and (V).

Related literature

For related literature, see: Allen (2002); Braunschweig et al. (2008); Brown et al. (1998); Grisby & Power (1996); Haberecht et al. (2004); Heilmann-Brohl, Schödel, Bolte, Wagner & Lerner (2011); Lorbach et al. (2012); Olmstead et al. (2003).

S2. Experimental

All experiments were carried out under dry nitrogen or argon with strict exclusion of air and moisture using standard Schlenk techniques. The starting materials were purchased from commercial sources and used without further purification. The solvents were distilled from sodium/benzophenone prior to use. C₆D₆ was dried over molecular sieves and stored under dry nitrogen. The NMR spectra were recorded on Bruker AM 250, DPX 250, Avance 300 and Avance 400 spectrometers. Abbreviations: s = singlet, d = doublet, t = triplet, q = quartet, quin = quintet, mult = multiplet and br = broad [pt = ?].

For the synthesis of (I), trimethylphenylsilane (8.5 ml, 49.2 mmol, 1 equivalent) was dissolved in hexane (10 ml) and cooled down to 273 K. BBr₃ (5 ml, 52.9 mmol, 1.1 equivalents) was added rapidly via a syringe. The mixture was allowed to warm slowly to room temperature and was then heated under reflux for 2 h. During removal of all volatile components in vacuo, dibromoborylbenzene was obtained as colourless crystals (yield 11.46 g, 94%). ¹H NMR (250.1 MHz, C₆D₆, δ, p.p.m.): 6.95 (pt, ³J_HH = 7.5 Hz, 2H, Ph—H^meta), 7.11 (t, ³J_HH = 7.4 Hz, 1H, Ph—H^para), 8.04 (d, ³J_HH = 7.6 Hz, 2H, Ph—H^ortho). ¹¹B NMR (128.4 MHz, C₆D₆, δ, p.p.m.): 57.4 (h_1/2 = 90 Hz). ¹³C NMR (62.9 MHz, C₆D₆, δ, p.p.m.): 128.3 (Ph—C^meta), 135.3 (Ph—C^para), 138.0 (Ph—C^ortho), n.b. (Ph—C^ipso). When a benzene (0.6 ml) solution of (I) (0.1 mmol) in the presence of an excess of HNMe₂ was left to stand for one week, single crystals of the composition PhBBr₂.HNMe₂, (IV), could be isolated.

For the synthesis of (II), 1,4-bis(trimethylsilyl)benzene (4.95 g, 21.8 mmol, 1 equivalent) and BBr₃ (2.3 ml, 23.9 mmol, 1.1 equivalents) were dissolved in hexane (15 ml) and stirred for 24 h at room temperature. The solution was evaporated to dryness in vacuo to give (II) as colourless crystals (yield 6.13 g, 86%). ¹H NMR (400.1 MHz, C₆D₆, δ, p.p.m.): 0.13 (s, 9H, SiMe₃), 7.34 (d, ³J_HH = 8.1 Hz, 2H, Ph—H^2/6), 8.08 (d, ³J_HH = 8.1 Hz, 2H, Ph—H^3/5). ¹¹B NMR (128.4 MHz, C₆D₆, δ, p.p.m.): 57.0 (h_1/2 = 280 Hz). ¹³C NMR (100.6 MHz, C₆D₆, δ, p.p.m.): -1.5 (SiMe₃), 133.3 (C^Ar), 136.8 (C^Ar), 150.1 (SiC^Ar), n.b. (BC^Ar). When a benzene (0.6 ml) solution of (II) (0.1 mmol) in the presence of an excess of SMe₂ was left to stand for one week, single crystals of the composition Me₃SiC₆H₄BBr₂.SMe₂, (V), could be isolated.

For the synthesis of (III), 4-bromo-1-(trimethylsilyl)benzene (4.3 ml, 21.8 mmol, 1 equivalent) was added in a solution of BBr₃ (2.3 ml, 23.9 mmol, 1.1 equivalents) and hexane (15 ml). After the mixture had been heated under reflux for 4 h, the solvent was removed in vacuo to give single crystals of (III) (yield 5.87 g, 82%). ¹H NMR (400.1 MHz, C₆D₆, δ, p.p.m.): 7.12 (d, ³J_HH = 8.3 Hz, 2H, Ph—H2/6), 7.66 (d, ³J_HH = 8.3 Hz, 2H, Ph—H^3/5). ¹¹B NMR (128.4 MHz, C₆D₆, δ, p.p.m.): 57.4 (h_1/2 = 180 Hz). ¹³C NMR (100.6 MHz, C₆D₆, δ, p.p.m.): 131.6 (C^Ar), 131.7 (BrC^Ar), 139.0 (C^Ar), n.b. (BC^Ar).

S3. Refinement

The H atoms were initially located by difference Fourier synthesis. Subsequently, H atoms bonded to C atoms were refined using a riding model, with methyl C—H = 0.98 Å, aromatic C—H = 0.95 Å and U_iso(H) = 1.5U_eq(C) for methyl or 1.2U_eq(C) for aromatic H atoms. The coordinates of the H atom bonded to the N atom in (IV) were refined with U_iso(H) = 1.2U_eq(N). Due to imposed crystallographic mirror symmetry, the central ring of (V), the S atom and one of the methyl groups bonded to the S atom are disordered over two equally occupied positions.

Computing details

For all compounds, data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA (Stoe & Cie, 2001); data reduction: X-AREA (Stoe & Cie, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. A perspective view of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. A packing diagram for (I), viewed in the ab plane.
	Fig. 3. A perspective view of (II), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 4. A packing diagram for (II), viewed in the bc plane.
	Fig. 5. A perspective view of (III), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 6. A packing diagram for (III), viewed in the ab plane. Br···Br contacts are shown as dashed lines.
	Fig. 7. A perspective view of (IV), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 8. A packing diagram for (IV), viewed in the bc plane. H atoms bonded to C atoms have been omitted for clarity. Hydrogen bonds are shown as dashed lines.
	Fig. 9. A perspective view of (V), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Only one of the two disordered orientations of the central ring is shown. [Symmetry code: (A) x, -y + 1/2, z.]

(I) dibromoborylbenzene

Crystal data

C6H5BBr2	F(000) = 928
Mr = 247.73	Dx = 2.140 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 8202 reflections
a = 11.0841 (16) Å	θ = 3.7–26.1°
b = 7.8287 (12) Å	µ = 10.45 mm^−1
c = 17.720 (2) Å	T = 173 K
V = 1537.6 (4) Å^3	Plate, colourless
Z = 8	0.29 × 0.17 × 0.09 mm

Data collection

Stoe IPDS II two-circle diffractometer	1517 independent reflections
Radiation source: fine-focus sealed tube	1089 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.081
ω scans	θmax = 26.1°, θmin = 3.7°
Absorption correction: multi-scan (MULABS; Spek, 2009; Blessing, 1995)	h = −13→13
Tmin = 0.152, Tmax = 0.453	k = −9→9
14258 measured reflections	l = −20→21

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)] = 0.050	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.110	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0417P)^2] where P = (Fo^2 + 2Fc^2)/3
1517 reflections	(Δ/σ)max < 0.001
82 parameters	Δρmax = 0.59 e Å^−3
0 restraints	Δρmin = −1.07 e Å^−3

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
B1	0.3987 (6)	0.3634 (9)	0.6298 (4)	0.0317 (14)
Br1	0.27993 (6)	0.49129 (9)	0.68469 (4)	0.0418 (2)
Br2	0.52293 (5)	0.26062 (10)	0.68982 (4)	0.0456 (2)
C1	0.3939 (5)	0.3424 (7)	0.5439 (3)	0.0282 (12)
C2	0.4773 (5)	0.2416 (8)	0.5056 (4)	0.0335 (13)
H2	0.5398	0.1865	0.5330	0.040*
C3	0.4706 (6)	0.2207 (8)	0.4287 (4)	0.0409 (15)
H3	0.5273	0.1493	0.4039	0.049*
C4	0.3819 (6)	0.3025 (9)	0.3869 (4)	0.0400 (14)
H4	0.3773	0.2879	0.3337	0.048*
C5	0.3005 (6)	0.4058 (9)	0.4244 (4)	0.0383 (14)
H5	0.2402	0.4640	0.3964	0.046*
C6	0.3050 (5)	0.4259 (8)	0.5009 (4)	0.0330 (13)
H6	0.2476	0.4970	0.5253	0.040*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
B1	0.031 (3)	0.035 (3)	0.030 (4)	−0.004 (3)	0.005 (3)	0.005 (3)
Br1	0.0396 (4)	0.0480 (4)	0.0377 (4)	0.0049 (3)	0.0047 (2)	−0.0098 (3)
Br2	0.0331 (3)	0.0690 (5)	0.0348 (4)	0.0059 (3)	−0.0021 (3)	0.0118 (3)
C1	0.023 (3)	0.030 (3)	0.032 (3)	−0.003 (2)	0.001 (2)	0.004 (2)
C2	0.024 (3)	0.041 (4)	0.035 (3)	0.000 (2)	0.001 (2)	−0.002 (3)
C3	0.038 (3)	0.044 (4)	0.041 (4)	−0.005 (3)	0.011 (3)	−0.010 (3)
C4	0.043 (3)	0.047 (4)	0.030 (3)	−0.008 (3)	0.000 (3)	−0.006 (3)
C5	0.034 (3)	0.045 (4)	0.036 (4)	−0.004 (3)	−0.003 (3)	0.007 (3)
C6	0.026 (3)	0.035 (3)	0.037 (4)	−0.001 (2)	0.002 (2)	−0.002 (3)

Geometric parameters (Å, º)

B1—C1	1.533 (9)	C3—C4	1.388 (10)
B1—Br2	1.917 (7)	C3—H3	0.9500
B1—Br1	1.919 (7)	C4—C5	1.381 (9)
C1—C2	1.392 (8)	C4—H4	0.9500
C1—C6	1.407 (8)	C5—C6	1.365 (9)
C2—C3	1.373 (9)	C5—H5	0.9500
C2—H2	0.9500	C6—H6	0.9500
C1—B1—Br2	122.1 (5)	C4—C3—H3	119.6
C1—B1—Br1	122.4 (5)	C5—C4—C3	118.4 (6)
Br2—B1—Br1	115.5 (4)	C5—C4—H4	120.8
C2—C1—C6	117.7 (6)	C3—C4—H4	120.8
C2—C1—B1	121.5 (5)	C6—C5—C4	121.4 (6)
C6—C1—B1	120.8 (5)	C6—C5—H5	119.3
C3—C2—C1	121.0 (6)	C4—C5—H5	119.3
C3—C2—H2	119.5	C5—C6—C1	120.6 (6)
C1—C2—H2	119.5	C5—C6—H6	119.7
C2—C3—C4	120.9 (6)	C1—C6—H6	119.7
C2—C3—H3	119.6
Br2—B1—C1—C2	2.6 (8)	C1—C2—C3—C4	1.4 (9)
Br1—B1—C1—C2	−176.6 (4)	C2—C3—C4—C5	0.0 (10)
Br2—B1—C1—C6	−176.9 (4)	C3—C4—C5—C6	−1.0 (10)
Br1—B1—C1—C6	3.9 (8)	C4—C5—C6—C1	0.5 (9)
C6—C1—C2—C3	−1.9 (8)	C2—C1—C6—C5	1.0 (8)
B1—C1—C2—C3	178.6 (6)	B1—C1—C6—C5	−179.5 (6)

(II) 1-dibromoboryl-4-(trimethylsilyl)benzene

Crystal data

C9H13BBr2Si	F(000) = 624
Mr = 319.91	Dx = 1.669 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 15049 reflections
a = 6.7452 (5) Å	θ = 3.3–26.1°
b = 15.2390 (12) Å	µ = 6.42 mm^−1
c = 12.4123 (10) Å	T = 173 K
β = 93.841 (6)°	Block, colourless
V = 1273.00 (17) Å^3	0.29 × 0.25 × 0.25 mm
Z = 4

Data collection

Stoe IPDS II two-circle diffractometer	2235 independent reflections
Radiation source: fine-focus sealed tube	1942 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.064
ω scans	θmax = 25.0°, θmin = 3.3°
Absorption correction: multi-scan (MULABS; Spek, 2009; Blessing, 1995)	h = −7→8
Tmin = 0.258, Tmax = 0.297	k = −18→18
19196 measured reflections	l = −14→14

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.036	H-atom parameters constrained
wR(F^2) = 0.084	w = 1/[σ^2(Fo^2) + (0.0311P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max < 0.001
2235 reflections	Δρmax = 0.46 e Å^−3
119 parameters	Δρmin = −0.37 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0112 (10)

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
Si1	0.84456 (13)	0.81255 (7)	0.56483 (7)	0.0410 (2)
B1	0.4716 (6)	0.4874 (3)	0.3170 (3)	0.0470 (9)
Br1	0.61752 (6)	0.38165 (3)	0.30091 (4)	0.06453 (18)
Br2	0.20678 (6)	0.48883 (3)	0.25108 (3)	0.05994 (17)
C1	0.7300 (5)	0.7162 (2)	0.4892 (2)	0.0397 (7)
C2	0.5444 (5)	0.7203 (3)	0.4322 (3)	0.0466 (8)
H2	0.4733	0.7742	0.4304	0.056*
C3	0.4613 (5)	0.6484 (2)	0.3784 (3)	0.0465 (8)
H3	0.3334	0.6536	0.3419	0.056*
C4	0.5617 (5)	0.5678 (2)	0.3764 (2)	0.0409 (7)
C5	0.7501 (5)	0.5635 (2)	0.4323 (3)	0.0449 (8)
H5	0.8232	0.5102	0.4323	0.054*
C6	0.8302 (5)	0.6354 (2)	0.4870 (3)	0.0459 (8)
H6	0.9572	0.6301	0.5244	0.055*
C7	1.0707 (6)	0.8454 (3)	0.4967 (3)	0.0613 (10)
H7A	1.0326	0.8645	0.4228	0.092*
H7B	1.1615	0.7953	0.4948	0.092*
H7C	1.1371	0.8938	0.5366	0.092*
C8	0.9122 (6)	0.7764 (3)	0.7058 (3)	0.0552 (9)
H8A	1.0076	0.7279	0.7050	0.083*
H8B	0.7925	0.7567	0.7393	0.083*
H8C	0.9720	0.8255	0.7472	0.083*
C9	0.6651 (6)	0.9049 (3)	0.5639 (3)	0.0576 (9)
H9A	0.6319	0.9235	0.4893	0.086*
H9B	0.7246	0.9542	0.6053	0.086*
H9C	0.5440	0.8858	0.5966	0.086*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Si1	0.0370 (4)	0.0426 (6)	0.0433 (5)	0.0023 (4)	0.0019 (3)	−0.0027 (4)
B1	0.050 (2)	0.051 (3)	0.0395 (19)	−0.0052 (18)	0.0032 (15)	0.0007 (16)
Br1	0.0647 (3)	0.0493 (3)	0.0789 (3)	0.00308 (18)	−0.00029 (19)	−0.01577 (19)
Br2	0.0561 (2)	0.0596 (3)	0.0615 (3)	−0.00835 (18)	−0.01491 (16)	0.00134 (17)
C1	0.0400 (16)	0.0421 (19)	0.0370 (15)	0.0028 (14)	0.0022 (12)	0.0016 (13)
C2	0.0417 (17)	0.046 (2)	0.0512 (18)	0.0078 (15)	0.0001 (13)	−0.0030 (15)
C3	0.0388 (16)	0.050 (2)	0.0495 (17)	0.0041 (15)	−0.0047 (13)	0.0008 (16)
C4	0.0433 (16)	0.043 (2)	0.0364 (15)	0.0004 (15)	0.0034 (12)	0.0021 (13)
C5	0.0447 (17)	0.039 (2)	0.0496 (18)	0.0081 (15)	−0.0025 (14)	0.0027 (14)
C6	0.0436 (17)	0.045 (2)	0.0473 (17)	0.0080 (15)	−0.0065 (13)	−0.0014 (15)
C7	0.0487 (19)	0.070 (3)	0.066 (2)	−0.0100 (19)	0.0118 (16)	−0.008 (2)
C8	0.059 (2)	0.058 (3)	0.0483 (19)	0.0006 (18)	−0.0029 (16)	−0.0059 (17)
C9	0.056 (2)	0.047 (2)	0.069 (2)	0.0081 (18)	0.0004 (17)	−0.0080 (18)

Geometric parameters (Å, º)

Si1—C9	1.856 (4)	C4—C5	1.408 (5)
Si1—C8	1.861 (4)	C5—C6	1.381 (5)
Si1—C7	1.862 (4)	C5—H5	0.9500
Si1—C1	1.881 (4)	C6—H6	0.9500
B1—C4	1.535 (5)	C7—H7A	0.9800
B1—Br1	1.906 (4)	C7—H7B	0.9800
B1—Br2	1.915 (4)	C7—H7C	0.9800
C1—C2	1.397 (5)	C8—H8A	0.9800
C1—C6	1.405 (5)	C8—H8B	0.9800
C2—C3	1.383 (5)	C8—H8C	0.9800
C2—H2	0.9500	C9—H9A	0.9800
C3—C4	1.403 (5)	C9—H9B	0.9800
C3—H3	0.9500	C9—H9C	0.9800
C9—Si1—C8	110.44 (19)	C4—C5—H5	119.5
C9—Si1—C7	110.3 (2)	C5—C6—C1	122.1 (3)
C8—Si1—C7	110.49 (19)	C5—C6—H6	118.9
C9—Si1—C1	110.06 (17)	C1—C6—H6	118.9
C8—Si1—C1	107.74 (17)	Si1—C7—H7A	109.5
C7—Si1—C1	107.75 (17)	Si1—C7—H7B	109.5
C4—B1—Br1	122.4 (3)	H7A—C7—H7B	109.5
C4—B1—Br2	121.6 (3)	Si1—C7—H7C	109.5
Br1—B1—Br2	116.0 (2)	H7A—C7—H7C	109.5
C2—C1—C6	116.5 (3)	H7B—C7—H7C	109.5
C2—C1—Si1	122.8 (3)	Si1—C8—H8A	109.5
C6—C1—Si1	120.8 (2)	Si1—C8—H8B	109.5
C3—C2—C1	122.0 (3)	H8A—C8—H8B	109.5
C3—C2—H2	119.0	Si1—C8—H8C	109.5
C1—C2—H2	119.0	H8A—C8—H8C	109.5
C2—C3—C4	121.4 (3)	H8B—C8—H8C	109.5
C2—C3—H3	119.3	Si1—C9—H9A	109.5
C4—C3—H3	119.3	Si1—C9—H9B	109.5
C3—C4—C5	117.0 (3)	H9A—C9—H9B	109.5
C3—C4—B1	122.1 (3)	Si1—C9—H9C	109.5
C5—C4—B1	120.9 (3)	H9A—C9—H9C	109.5
C6—C5—C4	121.0 (3)	H9B—C9—H9C	109.5
C6—C5—H5	119.5
C9—Si1—C1—C2	6.3 (3)	C2—C3—C4—B1	−180.0 (3)
C8—Si1—C1—C2	126.7 (3)	Br1—B1—C4—C3	173.2 (3)
C7—Si1—C1—C2	−114.0 (3)	Br2—B1—C4—C3	−5.1 (4)
C9—Si1—C1—C6	−174.1 (3)	Br1—B1—C4—C5	−7.2 (4)
C8—Si1—C1—C6	−53.6 (3)	Br2—B1—C4—C5	174.6 (3)
C7—Si1—C1—C6	65.6 (3)	C3—C4—C5—C6	0.6 (5)
C6—C1—C2—C3	1.4 (5)	B1—C4—C5—C6	−179.1 (3)
Si1—C1—C2—C3	−179.0 (3)	C4—C5—C6—C1	−0.6 (5)
C1—C2—C3—C4	−1.4 (5)	C2—C1—C6—C5	−0.4 (5)
C2—C3—C4—C5	0.4 (5)	Si1—C1—C6—C5	180.0 (3)

(III) 4-bromo-1-(dibromoboryl)benzene

Crystal data

C6H4BBr3	Dx = 2.488 Mg m^−3
Mr = 326.63	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I41/a	Cell parameters from 4723 reflections
Hall symbol: -I 4ad	θ = 2.8–25.6°
a = 29.446 (3) Å	µ = 13.80 mm^−1
c = 4.0228 (4) Å	T = 173 K
V = 3488.0 (8) Å^3	Needle, colourless
Z = 16	0.26 × 0.11 × 0.11 mm
F(000) = 2400

Data collection

Stoe IPDS II two-circle diffractometer	1544 independent reflections
Radiation source: fine-focus sealed tube	1111 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.097
ω scans	θmax = 25.0°, θmin = 2.8°
Absorption correction: multi-scan (MULABS; Spek, 2009; Blessing, 1995)	h = −35→35
Tmin = 0.124, Tmax = 0.312	k = −35→35
12710 measured reflections	l = −4→4

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)] = 0.070	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.149	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0652P)^2] where P = (Fo^2 + 2Fc^2)/3
1544 reflections	(Δ/σ)max < 0.001
91 parameters	Δρmax = 0.90 e Å^−3
0 restraints	Δρmin = −1.08 e Å^−3

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	0.28681 (5)	0.69376 (5)	0.6423 (3)	0.0440 (4)
Br2	0.25646 (5)	0.59109 (5)	0.8282 (3)	0.0442 (4)
Br3	0.04802 (4)	0.68695 (5)	0.0725 (3)	0.0388 (4)
B1	0.2401 (5)	0.6487 (5)	0.635 (3)	0.038 (3)
C1	0.1923 (4)	0.6581 (4)	0.502 (3)	0.029 (3)
C2	0.1825 (5)	0.6991 (4)	0.353 (3)	0.036 (3)
H2	0.2057	0.7214	0.3349	0.043*
C3	0.1394 (4)	0.7090 (4)	0.227 (3)	0.032 (3)
H3	0.1329	0.7378	0.1317	0.039*
C4	0.1066 (4)	0.6755 (4)	0.245 (3)	0.032 (3)
C5	0.1155 (4)	0.6337 (4)	0.387 (3)	0.037 (3)
H5	0.0927	0.6109	0.3989	0.044*
C6	0.1588 (5)	0.6261 (4)	0.512 (3)	0.041 (3)
H6	0.1654	0.5974	0.6083	0.049*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0338 (7)	0.0484 (9)	0.0498 (8)	−0.0035 (6)	−0.0031 (6)	0.0050 (6)
Br2	0.0422 (8)	0.0429 (8)	0.0475 (8)	0.0092 (6)	0.0010 (6)	0.0098 (6)
Br3	0.0334 (7)	0.0436 (8)	0.0394 (7)	−0.0018 (5)	−0.0035 (5)	0.0019 (6)
B1	0.047 (9)	0.046 (9)	0.020 (7)	0.005 (7)	0.007 (6)	−0.007 (6)
C1	0.032 (7)	0.034 (7)	0.022 (6)	−0.005 (5)	0.003 (4)	−0.009 (4)
C2	0.048 (8)	0.017 (6)	0.042 (7)	−0.010 (5)	0.007 (6)	0.007 (5)
C3	0.036 (7)	0.023 (6)	0.038 (7)	0.002 (5)	0.006 (5)	−0.001 (5)
C4	0.033 (7)	0.041 (7)	0.023 (6)	0.009 (6)	−0.003 (5)	−0.006 (5)
C5	0.038 (7)	0.027 (7)	0.045 (7)	−0.002 (5)	−0.005 (6)	−0.008 (5)
C6	0.060 (9)	0.022 (6)	0.041 (7)	0.008 (6)	0.006 (6)	−0.003 (5)

Geometric parameters (Å, º)

Br1—B1	1.911 (16)	C2—H2	0.9500
Br2—B1	1.926 (16)	C3—C4	1.381 (18)
Br3—C4	1.890 (12)	C3—H3	0.9500
B1—C1	1.53 (2)	C4—C5	1.385 (18)
C1—C6	1.365 (18)	C5—C6	1.388 (19)
C1—C2	1.381 (17)	C5—H5	0.9500
C2—C3	1.396 (18)	C6—H6	0.9500
C1—B1—Br1	122.8 (10)	C2—C3—H3	121.1
C1—B1—Br2	121.9 (11)	C3—C4—C5	121.7 (12)
Br1—B1—Br2	115.2 (8)	C3—C4—Br3	119.5 (9)
C6—C1—C2	117.7 (12)	C5—C4—Br3	118.8 (10)
C6—C1—B1	122.0 (12)	C4—C5—C6	117.7 (12)
C2—C1—B1	120.2 (11)	C4—C5—H5	121.1
C1—C2—C3	122.0 (11)	C6—C5—H5	121.1
C1—C2—H2	119.0	C1—C6—C5	122.9 (12)
C3—C2—H2	119.0	C1—C6—H6	118.5
C4—C3—C2	117.9 (11)	C5—C6—H6	118.5
C4—C3—H3	121.1
Br1—B1—C1—C6	−177.1 (9)	C2—C3—C4—C5	1.0 (18)
Br2—B1—C1—C6	−0.2 (16)	C2—C3—C4—Br3	−179.2 (9)
Br1—B1—C1—C2	5.9 (16)	C3—C4—C5—C6	−0.2 (18)
Br2—B1—C1—C2	−177.2 (9)	Br3—C4—C5—C6	−180.0 (9)
C6—C1—C2—C3	2.6 (18)	C2—C1—C6—C5	−1.8 (18)
B1—C1—C2—C3	179.7 (11)	B1—C1—C6—C5	−178.8 (11)
C1—C2—C3—C4	−2.3 (18)	C4—C5—C6—C1	0.6 (19)

(IV) dibromo(dimethylamino)(phenyl)borane

Crystal data

C8H12BBr2N	F(000) = 568
Mr = 292.82	Dx = 1.819 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4532 reflections
a = 8.9095 (9) Å	θ = 3.5–25.8°
b = 9.2874 (13) Å	µ = 7.53 mm^−1
c = 12.9306 (13) Å	T = 173 K
β = 92.249 (8)°	Block, colourless
V = 1069.1 (2) Å^3	0.19 × 0.09 × 0.05 mm
Z = 4

Data collection

Stoe IPDS II two-circle diffractometer	2004 independent reflections
Radiation source: fine-focus sealed tube	1413 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.082
ω scans	θmax = 25.6°, θmin = 3.5°
Absorption correction: multi-scan (MULABS; Spek, 2009; Blessing, 1995)	h = −10→9
Tmin = 0.329, Tmax = 0.705	k = −10→11
6363 measured reflections	l = −15→15

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.046	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.104	w = 1/[σ^2(Fo^2) + (0.0472P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.99	(Δ/σ)max < 0.001
2004 reflections	Δρmax = 0.98 e Å^−3
113 parameters	Δρmin = −0.96 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0035 (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
B1	0.1562 (8)	0.1816 (7)	0.4299 (4)	0.0238 (15)
Br1	0.19350 (9)	−0.00845 (7)	0.35462 (4)	0.0406 (2)
Br2	−0.06537 (8)	0.23148 (8)	0.39628 (5)	0.0402 (2)
N1	0.1676 (6)	0.1454 (6)	0.5521 (3)	0.0257 (11)
H1	0.102 (8)	0.080 (8)	0.563 (5)	0.031*
C1	0.3197 (8)	0.0914 (8)	0.5886 (4)	0.0388 (17)
H1A	0.3478	0.0087	0.5464	0.058*
H1B	0.3164	0.0621	0.6612	0.058*
H1C	0.3941	0.1683	0.5818	0.058*
C2	0.1254 (9)	0.2710 (8)	0.6194 (4)	0.0364 (16)
H2A	0.0255	0.3062	0.5973	0.055*
H2B	0.1991	0.3485	0.6127	0.055*
H2C	0.1242	0.2398	0.6917	0.055*
C11	0.2681 (7)	0.3076 (6)	0.3985 (3)	0.0236 (13)
C12	0.4201 (7)	0.2776 (7)	0.3746 (4)	0.0298 (14)
H12	0.4544	0.1807	0.3756	0.036*
C13	0.5186 (9)	0.3861 (8)	0.3500 (5)	0.0404 (18)
H13	0.6194	0.3637	0.3346	0.049*
C14	0.4701 (9)	0.5266 (8)	0.3479 (4)	0.0408 (19)
H14	0.5373	0.6010	0.3297	0.049*
C15	0.3260 (10)	0.5606 (8)	0.3719 (5)	0.0447 (19)
H15	0.2945	0.6583	0.3716	0.054*
C16	0.2252 (8)	0.4517 (7)	0.3967 (4)	0.0326 (15)
H16	0.1253	0.4766	0.4128	0.039*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
B1	0.033 (4)	0.025 (4)	0.014 (3)	0.003 (3)	0.001 (2)	0.002 (2)
Br1	0.0747 (6)	0.0223 (3)	0.0258 (3)	−0.0075 (4)	0.0150 (3)	−0.0051 (2)
Br2	0.0300 (4)	0.0557 (5)	0.0345 (3)	−0.0036 (4)	−0.0027 (2)	0.0187 (3)
N1	0.030 (3)	0.029 (3)	0.017 (2)	−0.002 (3)	0.001 (2)	−0.0004 (19)
C1	0.040 (4)	0.049 (4)	0.026 (3)	0.008 (4)	−0.005 (3)	0.005 (3)
C2	0.049 (4)	0.039 (4)	0.021 (3)	−0.007 (4)	0.002 (2)	−0.010 (3)
C11	0.036 (4)	0.022 (3)	0.012 (2)	−0.001 (3)	0.001 (2)	−0.001 (2)
C12	0.028 (3)	0.037 (4)	0.025 (3)	0.004 (3)	0.003 (2)	0.006 (2)
C13	0.032 (4)	0.056 (5)	0.034 (3)	−0.010 (4)	0.006 (3)	0.015 (3)
C14	0.052 (5)	0.048 (5)	0.023 (3)	−0.031 (4)	−0.003 (3)	0.003 (3)
C15	0.070 (6)	0.020 (3)	0.045 (3)	−0.011 (4)	0.012 (4)	−0.005 (3)
C16	0.044 (4)	0.021 (3)	0.034 (3)	−0.001 (3)	0.006 (3)	−0.002 (2)

Geometric parameters (Å, º)

B1—C11	1.600 (9)	C2—H2C	0.9800
B1—N1	1.615 (7)	C11—C16	1.392 (9)
B1—Br1	2.049 (6)	C11—C12	1.429 (9)
B1—Br2	2.058 (7)	C12—C13	1.381 (9)
N1—C1	1.503 (9)	C12—H12	0.9500
N1—C2	1.512 (8)	C13—C14	1.375 (10)
N1—H1	0.85 (7)	C13—H13	0.9500
C1—H1A	0.9800	C14—C15	1.369 (11)
C1—H1B	0.9800	C14—H14	0.9500
C1—H1C	0.9800	C15—C16	1.399 (10)
C2—H2A	0.9800	C15—H15	0.9500
C2—H2B	0.9800	C16—H16	0.9500
C11—B1—N1	112.6 (5)	N1—C2—H2C	109.5
C11—B1—Br1	113.3 (4)	H2A—C2—H2C	109.5
N1—B1—Br1	106.3 (4)	H2B—C2—H2C	109.5
C11—B1—Br2	112.6 (4)	C16—C11—C12	116.5 (6)
N1—B1—Br2	106.1 (4)	C16—C11—B1	122.3 (6)
Br1—B1—Br2	105.4 (3)	C12—C11—B1	121.2 (5)
C1—N1—C2	108.6 (5)	C13—C12—C11	121.6 (6)
C1—N1—B1	113.4 (5)	C13—C12—H12	119.2
C2—N1—B1	113.2 (5)	C11—C12—H12	119.2
C1—N1—H1	109 (5)	C14—C13—C12	119.6 (7)
C2—N1—H1	105 (4)	C14—C13—H13	120.2
B1—N1—H1	107 (4)	C12—C13—H13	120.2
N1—C1—H1A	109.5	C15—C14—C13	120.8 (7)
N1—C1—H1B	109.5	C15—C14—H14	119.6
H1A—C1—H1B	109.5	C13—C14—H14	119.6
N1—C1—H1C	109.5	C14—C15—C16	120.1 (7)
H1A—C1—H1C	109.5	C14—C15—H15	119.9
H1B—C1—H1C	109.5	C16—C15—H15	119.9
N1—C2—H2A	109.5	C11—C16—C15	121.4 (7)
N1—C2—H2B	109.5	C11—C16—H16	119.3
H2A—C2—H2B	109.5	C15—C16—H16	119.3
C11—B1—N1—C1	−62.4 (7)	Br1—B1—C11—C12	−34.4 (6)
Br1—B1—N1—C1	62.2 (6)	Br2—B1—C11—C12	−153.9 (4)
Br2—B1—N1—C1	174.1 (4)	C16—C11—C12—C13	−0.7 (8)
C11—B1—N1—C2	61.9 (7)	B1—C11—C12—C13	−178.3 (5)
Br1—B1—N1—C2	−173.4 (4)	C11—C12—C13—C14	−0.2 (9)
Br2—B1—N1—C2	−61.6 (6)	C12—C13—C14—C15	1.2 (9)
N1—B1—C11—C16	−91.3 (6)	C13—C14—C15—C16	−1.3 (9)
Br1—B1—C11—C16	148.1 (5)	C12—C11—C16—C15	0.6 (8)
Br2—B1—C11—C16	28.6 (6)	B1—C11—C16—C15	178.2 (5)
N1—B1—C11—C12	86.2 (6)	C14—C15—C16—C11	0.4 (9)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···Br1^i	0.85 (7)	2.96 (7)	3.705 (6)	147 (6)
N1—H1···Br2^i	0.85 (7)	2.96 (7)	3.684 (5)	143 (6)

Symmetry code: (i) −x, −y, −z+1.

(V) dibromo(dimethylsulfanyl)[4-(trimethylsilyl)phenyl]borane

Crystal data

C11H19BBr2SSi	F(000) = 760
Mr = 382.04	Dx = 1.576 Mg m^−3
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 4391 reflections
a = 6.6950 (5) Å	θ = 2.5–26.1°
b = 11.0880 (8) Å	µ = 5.21 mm^−1
c = 21.6870 (16) Å	T = 173 K
V = 1609.9 (2) Å^3	Needle, colourless
Z = 4	0.20 × 0.10 × 0.05 mm

Data collection

Stoe IPDS II two-circle diffractometer	1705 independent reflections
Radiation source: fine-focus sealed tube	1146 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.073
ω scans	θmax = 26.3°, θmin = 2.1°
Absorption correction: multi-scan (MULABS; Spek, 2009; Blessing, 1995)	h = −8→8
Tmin = 0.422, Tmax = 0.781	k = −13→13
22983 measured reflections	l = −26→26

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.037	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.083	w = 1/[σ^2(Fo^2) + (0.0454P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.90	(Δ/σ)max < 0.001
1705 reflections	Δρmax = 0.40 e Å^−3
110 parameters	Δρmin = −0.56 e Å^−3
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0045 (5)

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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	Occ. (<1)
Br1	0.37440 (6)	0.39945 (4)	0.329307 (19)	0.04263 (17)
B1	0.4191 (9)	0.2500	0.3810 (3)	0.0364 (16)
Si1	0.0014 (2)	0.2500	0.64318 (8)	0.0446 (5)
C11	0.0842 (7)	0.1116 (5)	0.6848 (2)	0.0569 (14)
H11A	0.0398	0.0400	0.6621	0.085*
H11B	0.0260	0.1108	0.7263	0.085*
H11C	0.2302	0.1112	0.6879	0.085*
C12	−0.2773 (8)	0.2500	0.6347 (3)	0.0528 (18)
H12A	−0.3193	0.1770	0.6127	0.079*	0.50
H12B	−0.3188	0.3214	0.6113	0.079*	0.50
H12C	−0.3394	0.2516	0.6756	0.079*
C1	0.3037 (7)	0.2500	0.4451 (3)	0.0336 (13)
C2	0.1890 (12)	0.1637 (7)	0.4669 (4)	0.0324 (17)	0.50
H2	0.1679	0.0945	0.4419	0.039*	0.50
C3	0.0962 (11)	0.1672 (7)	0.5247 (4)	0.0349 (18)	0.50
H3	0.0099	0.1024	0.5352	0.042*	0.50
C2'	0.3222 (11)	0.1412 (8)	0.4839 (4)	0.0358 (19)	0.50
H2'	0.3952	0.0736	0.4693	0.043*	0.50
C3'	0.2327 (12)	0.1373 (8)	0.5421 (4)	0.0365 (19)	0.50
H3'	0.2422	0.0676	0.5674	0.044*	0.50
C4	0.1185 (8)	0.2500	0.5637 (3)	0.0434 (15)
S1	0.7046 (2)	0.2722 (4)	0.40129 (8)	0.0332 (12)	0.50
C1S	0.8347 (7)	0.2500	0.3299 (3)	0.0457 (15)
H1S1	0.7872	0.1758	0.3102	0.068*	0.50
H1S2	0.9783	0.2434	0.3379	0.068*	0.50
H1S3	0.8097	0.3187	0.3025	0.068*	0.50
C2S	0.7549 (13)	0.1347 (8)	0.4431 (4)	0.044 (2)	0.50
H2S1	0.7309	0.0562	0.4237	0.067*	0.50
H2S2	0.6723	0.1419	0.4802	0.067*	0.50
H2S3	0.8962	0.1415	0.4544	0.067*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0363 (2)	0.0504 (3)	0.0412 (3)	0.0024 (2)	−0.00076 (19)	0.0077 (2)
B1	0.025 (3)	0.048 (4)	0.036 (4)	0.000	0.001 (2)	0.000
Si1	0.0298 (8)	0.0701 (13)	0.0340 (9)	0.000	0.0022 (7)	0.000
C11	0.043 (3)	0.083 (4)	0.044 (3)	0.005 (3)	0.0031 (19)	0.004 (3)
C12	0.033 (3)	0.073 (5)	0.053 (4)	0.000	0.007 (3)	0.000
C1	0.024 (2)	0.044 (4)	0.033 (3)	0.000	−0.003 (2)	0.000
C2	0.034 (4)	0.028 (4)	0.035 (4)	−0.003 (3)	0.002 (3)	−0.007 (4)
C3	0.031 (4)	0.035 (5)	0.039 (5)	−0.001 (4)	0.001 (3)	0.004 (4)
C2'	0.022 (4)	0.043 (5)	0.042 (5)	0.009 (3)	0.000 (3)	−0.001 (4)
C3'	0.032 (4)	0.037 (5)	0.040 (5)	0.005 (4)	0.009 (4)	0.010 (4)
C4	0.023 (2)	0.075 (5)	0.033 (3)	0.000	−0.002 (3)	0.000
S1	0.0215 (6)	0.040 (4)	0.0386 (9)	−0.0008 (9)	−0.0012 (6)	0.0011 (10)
C1S	0.025 (3)	0.062 (4)	0.050 (4)	0.000	0.006 (3)	0.000
C2S	0.039 (5)	0.045 (6)	0.049 (5)	0.006 (4)	−0.002 (4)	0.012 (4)

Geometric parameters (Å, º)

Br1—B1	2.022 (4)	C1—C2'	1.476 (9)
B1—C1	1.592 (8)	C2—C3	1.399 (11)
B1—S1	1.977 (6)	C2—H2	0.9500
B1—S1^i	1.977 (6)	C3—C4	1.258 (9)
B1—Br1^i	2.022 (4)	C3—H3	0.9500
Si1—C11^i	1.865 (5)	C2'—C3'	1.398 (11)
Si1—C11	1.865 (5)	C2'—H2'	0.9500
Si1—C12	1.874 (6)	C3'—C4	1.538 (9)
Si1—C4	1.893 (6)	C3'—H3'	0.9500
C11—H11A	0.9800	S1—C2S	1.806 (9)
C11—H11B	0.9800	S1—C1S	1.794 (6)
C11—H11C	0.9800	C1S—H1S1	0.9800
C12—H12A	0.9800	C1S—H1S2	0.9800
C12—H12B	0.9800	C1S—H1S3	0.9800
C12—H12C	0.9800	C2S—H2S1	0.9800
C1—C2	1.315 (8)	C2S—H2S2	0.9800
C1—C2^i	1.315 (8)	C2S—H2S3	0.9800
C1—C2'^i	1.476 (9)
C1—B1—S1	105.9 (4)	C4—C3—C2	124.8 (7)
C1—B1—S1^i	105.9 (4)	C2—C3—C3^i	91.6 (5)
C1—B1—Br1^i	114.3 (2)	C4—C3—H3	117.6
S1—B1—Br1^i	111.6 (2)	C2—C3—H3	117.6
S1^i—B1—Br1^i	99.5 (2)	C3^i—C3—H3	139.2
C1—B1—Br1	114.3 (2)	C3'—C2'—C1	120.3 (7)
S1—B1—Br1	99.5 (2)	C3'—C2'—H2'	119.9
S1^i—B1—Br1	111.6 (2)	C1—C2'—H2'	119.9
Br1^i—B1—Br1	110.0 (3)	C2'—C3'—C4	117.6 (7)
C11^i—Si1—C11	110.8 (3)	C2'—C3'—H3'	121.2
C11^i—Si1—C12	110.08 (18)	C4—C3'—H3'	121.2
C11—Si1—C12	110.08 (18)	C3—C4—C3^i	93.7 (8)
C11^i—Si1—C4	108.50 (17)	C3—C4—C3'^i	116.5 (6)
C11—Si1—C4	108.50 (17)	C3^i—C4—C3'	116.5 (6)
C12—Si1—C4	108.8 (3)	C3'^i—C4—C3'	108.7 (7)
Si1—C11—H11A	109.5	C3—C4—Si1	124.3 (4)
Si1—C11—H11B	109.5	C3^i—C4—Si1	124.3 (4)
H11A—C11—H11B	109.5	C3'^i—C4—Si1	118.9 (4)
Si1—C11—H11C	109.5	C3'—C4—Si1	118.9 (4)
H11A—C11—H11C	109.5	C2S^i—S1—C2S	104.5 (7)
H11B—C11—H11C	109.5	C2S^i—S1—C1S	122.5 (4)
Si1—C12—H12A	109.5	C2S—S1—C1S	103.1 (4)
Si1—C12—H12B	109.5	C2S^i—S1—B1	117.7 (4)
H12A—C12—H12B	109.5	C2S—S1—B1	100.8 (3)
Si1—C12—H12C	109.5	C1S—S1—B1	105.1 (3)
H12A—C12—H12C	109.5	S1—C1S—H1S1	109.5
H12B—C12—H12C	109.5	S1—C1S—H1S2	109.5
C2—C1—C2^i	93.4 (8)	H1S1—C1S—H1S2	109.5
C2—C1—C2'^i	116.0 (6)	S1—C1S—H1S3	109.5
C2^i—C1—C2'	116.0 (6)	H1S1—C1S—H1S3	109.5
C2'^i—C1—C2'	109.6 (8)	H1S2—C1S—H1S3	109.5
C2—C1—B1	126.7 (4)	S1^i—C2S—H2S1	109.5
C2^i—C1—B1	126.7 (4)	S1—C2S—H2S1	120.2
C2'^i—C1—B1	117.2 (4)	S1^i—C2S—H2S2	109.5
C2'—C1—B1	117.2 (4)	S1—C2S—H2S2	103.8
C1—C2—C3	124.1 (7)	H2S1—C2S—H2S2	109.5
C3—C2—C2^i	88.4 (5)	S1^i—C2S—H2S3	109.5
C1—C2—H2	117.9	S1—C2S—H2S3	103.9
C3—C2—H2	117.9	H2S1—C2S—H2S3	109.5
C2^i—C2—H2	143.8	H2S2—C2S—H2S3	109.5
S1—B1—C1—C2	−122.2 (6)	C2—C3—C4—Si1	−177.0 (6)
S1^i—B1—C1—C2	−107.3 (6)	C3^i—C3—C4—Si1	136.7 (8)
Br1^i—B1—C1—C2	1.2 (8)	C2'—C3'—C4—C3	71.2 (9)
Br1—B1—C1—C2	129.3 (6)	C2'—C3'—C4—C3^i	7.3 (11)
S1—B1—C1—C2^i	107.3 (6)	C2'—C3'—C4—C3'^i	−38.0 (11)
S1^i—B1—C1—C2^i	122.2 (6)	C2'—C3'—C4—Si1	−178.3 (6)
Br1^i—B1—C1—C2^i	−129.3 (6)	C11^i—Si1—C4—C3	178.2 (6)
Br1—B1—C1—C2^i	−1.2 (8)	C11—Si1—C4—C3	57.7 (6)
S1—B1—C1—C2'^i	59.3 (5)	C12—Si1—C4—C3	−62.0 (6)
S1^i—B1—C1—C2'^i	74.2 (5)	C11^i—Si1—C4—C3^i	−57.7 (6)
Br1^i—B1—C1—C2'^i	−177.3 (4)	C11—Si1—C4—C3^i	−178.2 (6)
Br1—B1—C1—C2'^i	−49.1 (6)	C12—Si1—C4—C3^i	62.0 (6)
S1—B1—C1—C2'	−74.2 (5)	C11^i—Si1—C4—C3'^i	−7.9 (5)
S1^i—B1—C1—C2'	−59.3 (5)	C11—Si1—C4—C3'^i	−128.3 (5)
Br1^i—B1—C1—C2'	49.1 (6)	C12—Si1—C4—C3'^i	111.9 (5)
Br1—B1—C1—C2'	177.3 (4)	C11^i—Si1—C4—C3'	128.3 (5)
C2^i—C1—C2—C3	−39.8 (12)	C11—Si1—C4—C3'	7.9 (5)
C2'^i—C1—C2—C3	−3.6 (12)	C12—Si1—C4—C3'	−111.9 (5)
C2'—C1—C2—C3	86.9 (10)	C1—B1—S1—S1^i	92.06 (7)
B1—C1—C2—C3	177.9 (6)	Br1^i—B1—S1—S1^i	−33.0 (2)
C2'^i—C1—C2—C2^i	36.1 (4)	Br1—B1—S1—S1^i	−149.1 (2)
C2'—C1—C2—C2^i	126.7 (7)	C1—B1—S1—C2S^i	−47.8 (5)
B1—C1—C2—C2^i	−142.4 (9)	S1^i—B1—S1—C2S^i	−139.9 (5)
C1—C2—C3—C4	−3.6 (14)	Br1^i—B1—S1—C2S^i	−172.9 (5)
C2^i—C2—C3—C4	−29.6 (8)	Br1—B1—S1—C2S^i	71.0 (5)
C1—C2—C3—C3^i	26.0 (8)	C1—B1—S1—C2S	65.0 (3)
C2^i—C2—C3—C3^i	0.000 (3)	S1^i—B1—S1—C2S	−27.1 (3)
C2—C1—C2'—C3'	−67.5 (8)	Br1^i—B1—S1—C2S	−60.1 (4)
C2^i—C1—C2'—C3'	−4.5 (11)	Br1—B1—S1—C2S	−176.2 (4)
C2'^i—C1—C2'—C3'	40.0 (11)	C1—B1—S1—C1S	171.85 (15)
B1—C1—C2'—C3'	176.9 (6)	S1^i—B1—S1—C1S	79.79 (18)
C1—C2'—C3'—C4	−0.7 (11)	Br1^i—B1—S1—C1S	46.8 (3)
C2—C3—C4—C3^i	46.3 (11)	Br1—B1—S1—C1S	−69.3 (3)
C2—C3—C4—C3'^i	8.9 (12)	C2S^i—S1—C2S—S1^i	180.000 (11)
C3^i—C3—C4—C3'^i	−37.3 (5)	C1S—S1—C2S—S1^i	−50.9 (5)
C2—C3—C4—C3'	−80.1 (9)	B1—S1—C2S—S1^i	57.5 (5)
C3^i—C3—C4—C3'	−126.4 (6)

Symmetry code: (i) x, −y+1/2, z.