Bis(η5-penta­methyl­cyclo­penta­dien­yl)aluminium tetra­bromido­aluminate

Purdy, A.P.; Dugger, C.; Butcher, R.J.

doi:10.1107/S1600536814002554

metal-organic compounds

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ISSN: 2056-9890

Volume 70| Part 3| March 2014| Pages m88-m89

doi:10.1107/S1600536814002554

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Bis(η⁵-pentamethylcyclopentadienyl)aluminium tetrabromidoaluminate

Andrew P. Purdy,^a ^* Cherrelle Dugger ^a ‡ and Ray J. Butcher ^b

^aNaval Research Laboratory, Chemistry Division, Code 6100, 4555 Overlook Av, SW, Washington, DC 20375, USA, and ^bDepartment of Chemistry, Howard University, 525 College Street NW, Washington, DC 20059, USA
^*Correspondence e-mail: andrew.purdy@nrl.navy.mil

(Received 25 November 2013; accepted 4 February 2014; online 8 February 2014)

The title compound, [Al(C₁₀H₁₅)₂][AlBr₄], was formed during the reduction of a mixture of Cp*AlBr₂ and AlBr₃. The Al^III atoms of the two crystallographically independent cations each lie on an inversion center, and the [AlBr₄]⁻ anions are on general positions. At 123 K, the structure exhibits disorder in two of the Br atoms of the [AlBr₄]⁻ ion, with a ratio occupancy of 0.733 (6): 0.267 (3). In the crystal, there is possible weak hydrogen bonding between some methyl groups and Br atoms. The interactions link the moieties in a three-dimensional array.

CCDC reference: 985069

Related literature

For the tetrachloridoaluminate analog of the title compound, see: Macdonald et al. (2008 ); Schurko et al. (2002 ). For the formation of the Cp*₂Al⁺ (decamethylaluminocenium) cation starting from (AlCp*)₄, see: Dohmeier et al. (1993 ); Üffing et al. (1998 ). For the formation of Cp*₂Al⁺ starting from Cp*₂AlX, see: Schurko et al. (2002). For other compounds containing this ion, see: Üffing et al. (1999 ); Kruczyński et al. (2012 ); Vollet et al. (2006 ); Burns et al. (1999 ). For the production of (Cp*Al)₄ by alkali metal reduction of Cp*AlX₂, see: Schormann et al. (2001 ); Minasian & Arnold (2008 ). For larger Al clusters containing the Cp* ligand, which have so far only been obtained from reactions between "AlX" and Cp* organometallics, see: Vollet et al. (2004 , 2005 ).

Experimental

Crystal data

[Al(C₁₀H₁₅)₂][AlBr₄]
M_r = 644.04
Triclinic, $[P \overline 1]$
a = 7.8152 (4) Å
b = 9.2949 (4) Å
c = 17.5420 (8) Å
α = 85.394 (4)°
β = 85.107 (4)°
γ = 82.659 (4)°
V = 1256.12 (10) Å³
Z = 2
Mo Kα radiation
μ = 6.48 mm⁻¹
T = 123 K
0.75 × 0.28 × 0.14 mm

Data collection

Agilent Xcalibur (Ruby, Gemini) diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012 ) T_min = 0.116, T_max = 0.506
19757 measured reflections
9539 independent reflections
5959 reflections with I > 2σ(I)
R_int = 0.038

Refinement

R[F² > 2σ(F²)] = 0.043
wR(F²) = 0.072
S = 0.91
9539 reflections
256 parameters
24 restraints
H-atom parameters constrained
Δρ_max = 1.58 e Å⁻³
Δρ_min = −1.29 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C7A—H7AA⋯Br3Bⁱ	0.98	3.03	3.886 (4)	146
C9A—H9AC⋯Br3A	0.98	3.04	3.773 (8)	133
C10A—H10E⋯Br3A	0.98	3.05	4.007 (7)	165
C9B—H9BB⋯Br1	0.98	2.95	3.770 (3)	141
Symmetry code: (i) -x+2, -y+2, -z.

Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS2013 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

CCDC reference: 985069

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536814002554/bh2490sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536814002554/bh2490Isup2.hkl

checkCIF report

Experimental top

Synthesis and crystallization top

The starting material Cp*AlBr₂ was prepared as previously reported (Schormann et al., 2001), and all compounds were handled in an Ar filled dry box or Schlenk glassware. Aluminium tribromide (0.4367 g, 1.63 mmol) was combined with Cp*AlBr₂ (0.1607 g, 0.50 mmol) in about 10 mL of dry toluene, and NaK₂ eutectic (0.2002 g, 1.97 mmol) was added. The Kontes valve on the tube was closed and the tube sonicated for 1 day in an ordinary sonic cleaner. Inside the dry box, the mixture was filtered to afford a yellow solution, which was pumped to dryness, affording 0.0619 g of raw product. Recrystallization from heptane by slow evaporation produced crystals of the title compound. ²⁷Al-NMR of product [reference: Al(NO₃)₃ in HNO₃ acidified water = 0 ppm]: -114.4 (Cp*₂Al⁺), 80.4 ppm (AlBr₄^-).

Refinement top

Crystal data, data collection and structure refinement details are summarized in Table 1. The bromine atoms Br3 and Br4 are disordered over two positions with occupancies of 0.733 (6) and 0.267 (6), respectively. These Br's along with Br1 and Br2 were restrained to be tetrahedral, i.e. Br1/Br2/Br3a/Br4a as one tetrahedral set and Br1/Br2/Br3b/Br4b as another tetrahedral set. The H atoms were placed in idealized positions, with CH₃ groups as rigid groups free to rotate and C—H bond lengths constrained to 0.98 Å.

Results and discussion top

The cluster compound (AlCp*)₄ is easily made from alkali metal reduction of Cp*AlX₂ (X=Cl, Br, I) compounds (Schormann et al., 2001; Minasian & Arnold, 2008), but larger Cp*Al clusters have only been reported from syntheses that start with Al(I) halide clusters, and that starting material requires a difficult and expensive apparatus to synthesize (Vollet et al., 2004, 2005). We attempted to prepare larger clusters by alkali reduction of mixtures of Cp*AlBr₂ and AlBr₃ in toluene. The soluble portion of the reaction mixture was recrystallized to afford the colorless title compound (Fig. 1). Other unidentified species with a broad ²⁷Al-NMR peak at -20 ppm and a sharp peak at 97 ppm were also present, in addition to Cp*₂Al ⁺ AlBr₄^-.

Decamethylaluminocenium tetrabromoaluminate has 1/2 of two Cp*₂Al⁺ cations in its asymmetric unit, as the two cations are crystallographically independent. As is normal for this cation, the Al atom is linear with the centroids of both rings, with the methyl groups staggered, and the linearity is in this case by symmetry. The two distinct decamethylaluminocenium cations are tilted with respect to each other as the dihedral angle between the ring planes of the two cations is 47.51°. This is in contrast with the AlCl₄^- analog (Schurko et al., 2002; Macdonald et al., 2008), which has two whole molecules in its unit cell, dihedral angles of 43.45-43.98° between the various Cp* ring planes, and near, but not exact, linearity of the centroids of the Cp* rings and their sandwiched Al atoms. The Cp*₂Al⁺ cation has also been reported in other compounds (Üffing et al., 1999; Kruczyński et al., 2012; Vollet et al., 2006; Burns et al., 1999). The AlBr₄^- anion shows disorder in two of the bromine atoms, and there appears to be weak hydrogen bonding interactions between some of the methyl protons and Br1 and Br3 (Fig. 2). While the angle between the undisordered Br atoms and Al3 (Br1—Al3—Br2) of 109.71 (4)° is close to the ideal tetrahedral angle of 109.5°, not much can really be said about the angles to the disordered Br atoms except that the geometry is approximately tetrahedral.

Based on other reports of Cp*₂Al⁺ formation (Dohmeier et al., 1993; Üffing et al., 1998), we presume that interactions between (AlCp*)₄ and AlBr₃ is probably responsible for the formation of the title compound. A repeat of the same reduction reaction at 0 °C resulted in (AlCp*)₄ as the only soluble Al-containing product, based on its ²⁷Al-NMR peak at -80.7 ppm.

Related literature top

For the tetrachloridoaluminate analog of the title compound, see: Macdonald et al. (2008); Schurko et al. (2002). For the formation of the Cp*₂Al⁺ (decamethylaluminocenium) cation starting from (AlCp*)_4, see: Dohmeier et al. (1993); Üffing et al. (1998). For the formation of Cp*₂Al⁺ starting from Cp*₂AlX, see: Schurko et al. (2002). For other compounds containing this ion, see: Üffing et al. (1999); Kruczyński et al. (2012); Vollet et al. (2006); Burns et al. (1999). This ion appears to be a thermodynamic or kinetic sink in Cp*-aluminium chemistry. For the production of (Cp*Al)₄ by alkali metal reduction of Cp*AlX₂, see: Schormann et al. (2001); Minasian & Arnold (2008). For larger Al clusters containing the Cp* ligand, which have so far only been obtained from reactions between "AlX" and Cp* organometallics, see: Vollet et al. (2004, 2005).

Computing details top

Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS2013 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. Structure of the title compound. Both nonequivalent decamethylaluminocenium cations placed on inversion centers are shown. Disordered atoms Br3b and Br4b have been omitted for clarity.
	Fig. 2. Packing diagram showing the crystal structure and the hydrogen bonding scheme (dashed lines).

Bis(η⁵-pentamethylcyclopentadienyl)aluminium tetrabromidoaluminate top

Crystal data top

[Al(C₁₀H₁₅)₂][AlBr₄]	Z = 2
M_r = 644.04	F(000) = 632
Triclinic, P1	D_x = 1.703 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.8152 (4) Å	Cell parameters from 5355 reflections
b = 9.2949 (4) Å	θ = 3.1–40.9°
c = 17.5420 (8) Å	µ = 6.48 mm⁻¹
α = 85.394 (4)°	T = 123 K
β = 85.107 (4)°	Prism, colorless
γ = 82.659 (4)°	0.75 × 0.28 × 0.14 mm
V = 1256.12 (10) Å³

Data collection top

Agilent Xcalibur (Ruby, Gemini) diffractometer	9539 independent reflections
Radiation source: Enhance (Mo) X-ray Source	5959 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.038
Detector resolution: 10.5081 pixels mm^-1	θ_max = 33.1°, θ_min = 3.1°
ω scans	h = −12→9
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	k = −14→14
T_min = 0.116, T_max = 0.506	l = −23→26
19757 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.043	H-atom parameters constrained
wR(F²) = 0.072	w = 1/[σ²(F_o²)] where P = (F_o² + 2F_c²)/3
S = 0.91	(Δ/σ)_max = 0.001
9539 reflections	Δρ_max = 1.58 e Å⁻³
256 parameters	Δρ_min = −1.29 e Å⁻³
24 restraints	Extinction correction: SHELXL2013 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 constraints	Extinction coefficient: 0.00092 (12)
Primary atom site location: structure-invariant direct methods

Crystal data top

[Al(C₁₀H₁₅)₂][AlBr₄]	γ = 82.659 (4)°
M_r = 644.04	V = 1256.12 (10) Å³
Triclinic, P1	Z = 2
a = 7.8152 (4) Å	Mo Kα radiation
b = 9.2949 (4) Å	µ = 6.48 mm⁻¹
c = 17.5420 (8) Å	T = 123 K
α = 85.394 (4)°	0.75 × 0.28 × 0.14 mm
β = 85.107 (4)°

Data collection top

Agilent Xcalibur (Ruby, Gemini) diffractometer	9539 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	5959 reflections with I > 2σ(I)
T_min = 0.116, T_max = 0.506	R_int = 0.038
19757 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.043	24 restraints
wR(F²) = 0.072	H-atom parameters constrained
S = 0.91	Δρ_max = 1.58 e Å⁻³
9539 reflections	Δρ_min = −1.29 e Å⁻³
256 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Br1	0.96698 (4)	0.21881 (3)	0.25435 (2)	0.03406 (8)
Br2	0.65528 (4)	0.55941 (4)	0.27080 (2)	0.03666 (9)
Br3A	0.9871 (7)	0.5256 (8)	0.1151 (4)	0.0541 (4)	0.267 (6)
Br4A	1.0853 (5)	0.5280 (4)	0.3398 (3)	0.0544 (4)	0.267 (6)
Br3B	1.0273 (3)	0.5371 (3)	0.11613 (15)	0.0541 (4)	0.733 (6)
Br4B	1.1204 (2)	0.55802 (18)	0.31528 (14)	0.0544 (4)	0.733 (6)
Al1	0.5000	1.0000	0.0000	0.0211 (2)
Al2	0.5000	0.0000	0.5000	0.0181 (2)
Al3	0.93792 (11)	0.46832 (9)	0.24082 (5)	0.02554 (19)
C1A	0.6158 (4)	1.1583 (3)	0.05506 (15)	0.0267 (6)
C2A	0.6105 (4)	1.2014 (3)	−0.02423 (15)	0.0251 (6)
C3A	0.7084 (4)	1.0894 (3)	−0.06667 (15)	0.0243 (6)
C4A	0.7753 (3)	0.9763 (3)	−0.01345 (15)	0.0247 (6)
C5A	0.7184 (4)	1.0177 (3)	0.06290 (15)	0.0248 (6)
C6A	0.5357 (4)	1.2443 (3)	0.12124 (16)	0.0364 (8)
H6AA	0.6188	1.3054	0.1362	0.055*
H6AB	0.5048	1.1774	0.1648	0.055*
H6AC	0.4315	1.3061	0.1057	0.055*
C7A	0.5193 (4)	1.3404 (3)	−0.05916 (17)	0.0338 (7)
H7AA	0.6012	1.4122	−0.0698	0.051*
H7AB	0.4241	1.3781	−0.0233	0.051*
H7AC	0.4731	1.3213	−0.1071	0.051*
C8A	0.7364 (4)	1.0949 (3)	−0.15239 (15)	0.0311 (7)
H8AA	0.8285	1.1551	−0.1694	0.047*
H8AB	0.6292	1.1368	−0.1750	0.047*
H8AC	0.7700	0.9962	−0.1688	0.047*
C9A	0.8866 (4)	0.8369 (3)	−0.03221 (16)	0.0298 (6)
H9AA	1.0049	0.8411	−0.0187	0.045*
H9AB	0.8877	0.8244	−0.0872	0.045*
H9AC	0.8395	0.7547	−0.0029	0.045*
C10A	0.7629 (4)	0.9341 (3)	0.13688 (16)	0.0320 (7)
H10D	0.8595	0.9730	0.1570	0.048*
H10E	0.7962	0.8313	0.1277	0.048*
H10F	0.6621	0.9434	0.1742	0.048*
C1B	0.6860 (3)	0.0207 (3)	0.58074 (15)	0.0217 (5)
C2B	0.6425 (3)	−0.1248 (3)	0.58812 (15)	0.0230 (6)
C3B	0.6905 (3)	−0.1866 (3)	0.51579 (15)	0.0222 (5)
C4B	0.7604 (3)	−0.0790 (3)	0.46392 (15)	0.0217 (5)
C5B	0.7598 (3)	0.0501 (3)	0.50399 (15)	0.0215 (5)
C6B	0.6614 (4)	0.1239 (3)	0.64341 (16)	0.0324 (7)
H6BA	0.7571	0.1021	0.6768	0.049*
H6BB	0.5518	0.1131	0.6736	0.049*
H6BC	0.6593	0.2240	0.6208	0.049*
C7B	0.5666 (4)	−0.1986 (3)	0.65955 (16)	0.0315 (7)
H7BA	0.6585	−0.2338	0.6935	0.047*
H7BB	0.5110	−0.2810	0.6462	0.047*
H7BC	0.4805	−0.1295	0.6857	0.047*
C8B	0.6735 (4)	−0.3398 (3)	0.49793 (18)	0.0327 (7)
H8BA	0.7824	−0.4019	0.5061	0.049*
H8BB	0.6470	−0.3405	0.4444	0.049*
H8BC	0.5800	−0.3767	0.5317	0.049*
C9B	0.8314 (3)	−0.0988 (3)	0.38248 (15)	0.0290 (6)
H9BA	0.9574	−0.1228	0.3809	0.043*
H9BB	0.8025	−0.0085	0.3509	0.043*
H9BC	0.7804	−0.1778	0.3626	0.043*
C10B	0.8249 (4)	0.1886 (3)	0.47134 (17)	0.0288 (6)
H10A	0.9509	0.1721	0.4615	0.043*
H10B	0.7944	0.2637	0.5080	0.043*
H10C	0.7719	0.2205	0.4232	0.043*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0522 (2)	0.02018 (14)	0.02845 (16)	−0.00475 (13)	0.00479 (14)	−0.00135 (11)
Br2	0.02744 (15)	0.04200 (19)	0.03929 (19)	0.00291 (14)	0.00066 (13)	−0.01010 (14)
Br3A	0.0598 (9)	0.0352 (4)	0.0534 (3)	0.0103 (6)	0.0309 (7)	0.0184 (3)
Br4A	0.0404 (5)	0.0323 (5)	0.0970 (10)	−0.0003 (4)	−0.0318 (6)	−0.0236 (6)
Br3B	0.0598 (9)	0.0352 (4)	0.0534 (3)	0.0103 (6)	0.0309 (7)	0.0184 (3)
Br4B	0.0404 (5)	0.0323 (5)	0.0970 (10)	−0.0003 (4)	−0.0318 (6)	−0.0236 (6)
Al1	0.0283 (6)	0.0169 (5)	0.0179 (6)	−0.0012 (5)	−0.0026 (4)	−0.0020 (4)
Al2	0.0161 (5)	0.0206 (5)	0.0172 (5)	−0.0002 (4)	−0.0017 (4)	−0.0013 (4)
Al3	0.0259 (4)	0.0191 (4)	0.0315 (5)	−0.0011 (3)	−0.0023 (3)	−0.0029 (3)
C1A	0.0390 (16)	0.0183 (12)	0.0230 (14)	−0.0020 (12)	−0.0037 (12)	−0.0032 (11)
C2A	0.0374 (15)	0.0168 (12)	0.0210 (13)	−0.0038 (11)	−0.0037 (11)	0.0016 (10)
C3A	0.0314 (14)	0.0207 (13)	0.0211 (13)	−0.0052 (11)	−0.0003 (11)	−0.0015 (10)
C4A	0.0288 (14)	0.0223 (13)	0.0228 (14)	−0.0035 (11)	−0.0005 (11)	−0.0008 (11)
C5A	0.0327 (14)	0.0227 (13)	0.0197 (13)	−0.0026 (12)	−0.0070 (11)	−0.0008 (10)
C6A	0.057 (2)	0.0279 (15)	0.0243 (15)	0.0056 (15)	−0.0104 (14)	−0.0110 (12)
C7A	0.0491 (19)	0.0212 (14)	0.0313 (16)	−0.0014 (14)	−0.0102 (14)	−0.0004 (12)
C8A	0.0373 (16)	0.0341 (16)	0.0209 (14)	−0.0047 (13)	0.0012 (12)	0.0004 (12)
C9A	0.0322 (15)	0.0277 (15)	0.0282 (15)	0.0008 (12)	0.0004 (12)	−0.0043 (12)
C10A	0.0412 (17)	0.0301 (15)	0.0245 (15)	0.0008 (14)	−0.0085 (13)	−0.0016 (12)
C1B	0.0197 (12)	0.0250 (13)	0.0206 (13)	−0.0006 (11)	−0.0047 (10)	−0.0027 (10)
C2B	0.0208 (12)	0.0279 (14)	0.0188 (13)	0.0015 (11)	−0.0022 (10)	0.0015 (10)
C3B	0.0196 (12)	0.0218 (13)	0.0237 (13)	0.0026 (10)	−0.0007 (10)	−0.0009 (10)
C4B	0.0189 (11)	0.0248 (13)	0.0208 (13)	−0.0001 (10)	0.0002 (10)	−0.0040 (10)
C5B	0.0185 (11)	0.0247 (13)	0.0212 (13)	−0.0016 (10)	−0.0021 (10)	−0.0009 (10)
C6B	0.0347 (15)	0.0430 (18)	0.0207 (14)	−0.0030 (14)	−0.0037 (12)	−0.0103 (13)
C7B	0.0306 (15)	0.0385 (17)	0.0219 (14)	−0.0004 (13)	0.0008 (12)	0.0093 (12)
C8B	0.0371 (16)	0.0222 (14)	0.0375 (17)	−0.0003 (13)	−0.0019 (13)	−0.0007 (12)
C9B	0.0276 (14)	0.0335 (16)	0.0241 (14)	0.0008 (12)	0.0050 (11)	−0.0058 (12)
C10B	0.0268 (14)	0.0289 (15)	0.0308 (16)	−0.0069 (12)	−0.0001 (12)	−0.0003 (12)

Geometric parameters (Å, º) top

Br1—Al3	2.2963 (9)	C6A—H6AC	0.9800
Br2—Al3	2.2952 (8)	C7A—H7AA	0.9800
Br3A—Al3	2.239 (7)	C7A—H7AB	0.9800
Br4A—Al3	2.304 (4)	C7A—H7AC	0.9800
Br3B—Al3	2.304 (2)	C8A—H8AA	0.9800
Br4B—Al3	2.2869 (14)	C8A—H8AB	0.9800
Al1—C4A	2.129 (3)	C8A—H8AC	0.9800
Al1—C4Aⁱ	2.129 (3)	C9A—H9AA	0.9800
Al1—C3A	2.139 (3)	C9A—H9AB	0.9800
Al1—C3Aⁱ	2.139 (3)	C9A—H9AC	0.9800
Al1—C5A	2.140 (3)	C10A—H10D	0.9800
Al1—C5Aⁱ	2.140 (3)	C10A—H10E	0.9800
Al1—C1Aⁱ	2.153 (3)	C10A—H10F	0.9800
Al1—C1A	2.153 (3)	C1B—C2B	1.429 (4)
Al1—C2A	2.157 (3)	C1B—C5B	1.438 (4)
Al1—C2Aⁱ	2.157 (3)	C1B—C6B	1.501 (3)
Al2—C4Bⁱⁱ	2.134 (2)	C2B—C3B	1.436 (3)
Al2—C4B	2.134 (2)	C2B—C7B	1.494 (4)
Al2—C5Bⁱⁱ	2.148 (3)	C3B—C4B	1.426 (4)
Al2—C5B	2.148 (3)	C3B—C8B	1.507 (4)
Al2—C1B	2.150 (3)	C4B—C5B	1.438 (3)
Al2—C1Bⁱⁱ	2.150 (3)	C4B—C9B	1.504 (3)
Al2—C3Bⁱⁱ	2.152 (2)	C5B—C10B	1.497 (4)
Al2—C3B	2.152 (2)	C6B—H6BA	0.9800
Al2—C2Bⁱⁱ	2.157 (3)	C6B—H6BB	0.9800
Al2—C2B	2.157 (3)	C6B—H6BC	0.9800
C1A—C2A	1.419 (4)	C7B—H7BA	0.9800
C1A—C5A	1.447 (3)	C7B—H7BB	0.9800
C1A—C6A	1.508 (3)	C7B—H7BC	0.9800
C2A—C3A	1.431 (3)	C8B—H8BA	0.9800
C2A—C7A	1.505 (4)	C8B—H8BB	0.9800
C3A—C4A	1.427 (4)	C8B—H8BC	0.9800
C3A—C8A	1.499 (4)	C9B—H9BA	0.9800
C4A—C5A	1.441 (3)	C9B—H9BB	0.9800
C4A—C9A	1.508 (3)	C9B—H9BC	0.9800
C5A—C10A	1.502 (4)	C10B—H10A	0.9800
C6A—H6AA	0.9800	C10B—H10B	0.9800
C6A—H6AB	0.9800	C10B—H10C	0.9800

C4A—Al1—C4Aⁱ	180.0	C3A—C2A—Al1	69.87 (16)
C4A—Al1—C3A	39.05 (10)	C7A—C2A—Al1	125.4 (2)
C4Aⁱ—Al1—C3A	140.95 (10)	C4A—C3A—C2A	108.3 (2)
C4A—Al1—C3Aⁱ	140.95 (10)	C4A—C3A—C8A	127.0 (2)
C4Aⁱ—Al1—C3Aⁱ	39.05 (10)	C2A—C3A—C8A	124.7 (2)
C3A—Al1—C3Aⁱ	180.0	C4A—C3A—Al1	70.10 (17)
C4A—Al1—C5A	39.46 (10)	C2A—C3A—Al1	71.23 (16)
C4Aⁱ—Al1—C5A	140.54 (10)	C8A—C3A—Al1	125.4 (2)
C3A—Al1—C5A	65.71 (11)	C3A—C4A—C5A	108.1 (2)
C3Aⁱ—Al1—C5A	114.29 (11)	C3A—C4A—C9A	126.9 (2)
C4A—Al1—C5Aⁱ	140.54 (10)	C5A—C4A—C9A	125.0 (2)
C4Aⁱ—Al1—C5Aⁱ	39.46 (10)	C3A—C4A—Al1	70.85 (16)
C3A—Al1—C5Aⁱ	114.29 (11)	C5A—C4A—Al1	70.68 (15)
C3Aⁱ—Al1—C5Aⁱ	65.71 (11)	C9A—C4A—Al1	124.2 (2)
C5A—Al1—C5Aⁱ	180.0	C4A—C5A—C1A	107.1 (2)
C4A—Al1—C1Aⁱ	114.31 (10)	C4A—C5A—C10A	126.7 (2)
C4Aⁱ—Al1—C1Aⁱ	65.69 (10)	C1A—C5A—C10A	126.2 (2)
C3A—Al1—C1Aⁱ	114.91 (10)	C4A—C5A—Al1	69.86 (15)
C3Aⁱ—Al1—C1Aⁱ	65.09 (10)	C1A—C5A—Al1	70.79 (16)
C5A—Al1—C1Aⁱ	140.62 (10)	C10A—C5A—Al1	126.4 (2)
C5Aⁱ—Al1—C1Aⁱ	39.38 (10)	C1A—C6A—H6AA	109.5
C4A—Al1—C1A	65.69 (10)	C1A—C6A—H6AB	109.5
C4Aⁱ—Al1—C1A	114.31 (10)	H6AA—C6A—H6AB	109.5
C3A—Al1—C1A	65.09 (10)	C1A—C6A—H6AC	109.5
C3Aⁱ—Al1—C1A	114.90 (10)	H6AA—C6A—H6AC	109.5
C5A—Al1—C1A	39.38 (10)	H6AB—C6A—H6AC	109.5
C5Aⁱ—Al1—C1A	140.62 (10)	C2A—C7A—H7AA	109.5
C1Aⁱ—Al1—C1A	180.00 (12)	C2A—C7A—H7AB	109.5
C4A—Al1—C2A	65.39 (10)	H7AA—C7A—H7AB	109.5
C4Aⁱ—Al1—C2A	114.61 (10)	C2A—C7A—H7AC	109.5
C3A—Al1—C2A	38.90 (9)	H7AA—C7A—H7AC	109.5
C3Aⁱ—Al1—C2A	141.10 (9)	H7AB—C7A—H7AC	109.5
C5A—Al1—C2A	65.43 (11)	C3A—C8A—H8AA	109.5
C5Aⁱ—Al1—C2A	114.57 (11)	C3A—C8A—H8AB	109.5
C1Aⁱ—Al1—C2A	141.56 (10)	H8AA—C8A—H8AB	109.5
C1A—Al1—C2A	38.44 (10)	C3A—C8A—H8AC	109.5
C4A—Al1—C2Aⁱ	114.61 (10)	H8AA—C8A—H8AC	109.5
C4Aⁱ—Al1—C2Aⁱ	65.39 (10)	H8AB—C8A—H8AC	109.5
C3A—Al1—C2Aⁱ	141.10 (9)	C4A—C9A—H9AA	109.5
C3Aⁱ—Al1—C2Aⁱ	38.90 (9)	C4A—C9A—H9AB	109.5
C5A—Al1—C2Aⁱ	114.57 (11)	H9AA—C9A—H9AB	109.5
C5Aⁱ—Al1—C2Aⁱ	65.43 (11)	C4A—C9A—H9AC	109.5
C1Aⁱ—Al1—C2Aⁱ	38.44 (10)	H9AA—C9A—H9AC	109.5
C1A—Al1—C2Aⁱ	141.56 (10)	H9AB—C9A—H9AC	109.5
C2A—Al1—C2Aⁱ	180.0	C5A—C10A—H10D	109.5
C4Bⁱⁱ—Al2—C4B	180.0	C5A—C10A—H10E	109.5
C4Bⁱⁱ—Al2—C5Bⁱⁱ	39.25 (9)	H10D—C10A—H10E	109.5
C4B—Al2—C5Bⁱⁱ	140.75 (9)	C5A—C10A—H10F	109.5
C4Bⁱⁱ—Al2—C5B	140.75 (9)	H10D—C10A—H10F	109.5
C4B—Al2—C5B	39.25 (9)	H10E—C10A—H10F	109.5
C5Bⁱⁱ—Al2—C5B	180.00 (14)	C2B—C1B—C5B	108.7 (2)
C4Bⁱⁱ—Al2—C1B	114.57 (9)	C2B—C1B—C6B	125.4 (3)
C4B—Al2—C1B	65.43 (9)	C5B—C1B—C6B	126.0 (3)
C5Bⁱⁱ—Al2—C1B	140.90 (10)	C2B—C1B—Al2	70.88 (14)
C5B—Al2—C1B	39.10 (10)	C5B—C1B—Al2	70.40 (14)
C4Bⁱⁱ—Al2—C1Bⁱⁱ	65.43 (9)	C6B—C1B—Al2	125.53 (17)
C4B—Al2—C1Bⁱⁱ	114.57 (9)	C1B—C2B—C3B	107.5 (2)
C5Bⁱⁱ—Al2—C1Bⁱⁱ	39.10 (10)	C1B—C2B—C7B	125.5 (2)
C5B—Al2—C1Bⁱⁱ	140.90 (10)	C3B—C2B—C7B	127.0 (3)
C1B—Al2—C1Bⁱⁱ	180.0	C1B—C2B—Al2	70.37 (14)
C4Bⁱⁱ—Al2—C3Bⁱⁱ	38.87 (10)	C3B—C2B—Al2	70.39 (15)
C4B—Al2—C3Bⁱⁱ	141.13 (10)	C7B—C2B—Al2	126.15 (18)
C5Bⁱⁱ—Al2—C3Bⁱⁱ	65.33 (10)	C4B—C3B—C2B	108.4 (2)
C5B—Al2—C3Bⁱⁱ	114.67 (10)	C4B—C3B—C8B	125.7 (2)
C1B—Al2—C3Bⁱⁱ	115.04 (9)	C2B—C3B—C8B	126.0 (3)
C1Bⁱⁱ—Al2—C3Bⁱⁱ	64.96 (9)	C4B—C3B—Al2	69.87 (14)
C4Bⁱⁱ—Al2—C3B	141.13 (10)	C2B—C3B—Al2	70.69 (13)
C4B—Al2—C3B	38.87 (10)	C8B—C3B—Al2	126.13 (19)
C5Bⁱⁱ—Al2—C3B	114.67 (10)	C3B—C4B—C5B	108.3 (2)
C5B—Al2—C3B	65.33 (10)	C3B—C4B—C9B	126.2 (2)
C1B—Al2—C3B	64.96 (9)	C5B—C4B—C9B	125.5 (3)
C1Bⁱⁱ—Al2—C3B	115.04 (9)	C3B—C4B—Al2	71.26 (13)
C3Bⁱⁱ—Al2—C3B	180.0	C5B—C4B—Al2	70.91 (13)
C4Bⁱⁱ—Al2—C2Bⁱⁱ	65.48 (10)	C9B—C4B—Al2	125.92 (18)
C4B—Al2—C2Bⁱⁱ	114.52 (10)	C4B—C5B—C1B	107.2 (2)
C5Bⁱⁱ—Al2—C2Bⁱⁱ	65.51 (11)	C4B—C5B—C10B	126.0 (2)
C5B—Al2—C2Bⁱⁱ	114.49 (11)	C1B—C5B—C10B	126.8 (2)
C1B—Al2—C2Bⁱⁱ	141.24 (10)	C4B—C5B—Al2	69.84 (15)
C1Bⁱⁱ—Al2—C2Bⁱⁱ	38.76 (10)	C1B—C5B—Al2	70.50 (15)
C3Bⁱⁱ—Al2—C2Bⁱⁱ	38.92 (9)	C10B—C5B—Al2	125.03 (17)
C3B—Al2—C2Bⁱⁱ	141.08 (9)	C1B—C6B—H6BA	109.5
C4Bⁱⁱ—Al2—C2B	114.52 (10)	C1B—C6B—H6BB	109.5
C4B—Al2—C2B	65.48 (10)	H6BA—C6B—H6BB	109.5
C5Bⁱⁱ—Al2—C2B	114.49 (11)	C1B—C6B—H6BC	109.5
C5B—Al2—C2B	65.51 (11)	H6BA—C6B—H6BC	109.5
C1B—Al2—C2B	38.76 (10)	H6BB—C6B—H6BC	109.5
C1Bⁱⁱ—Al2—C2B	141.24 (10)	C2B—C7B—H7BA	109.5
C3Bⁱⁱ—Al2—C2B	141.08 (9)	C2B—C7B—H7BB	109.5
C3B—Al2—C2B	38.92 (9)	H7BA—C7B—H7BB	109.5
C2Bⁱⁱ—Al2—C2B	180.00 (10)	C2B—C7B—H7BC	109.5
Br3A—Al3—Br2	105.36 (15)	H7BA—C7B—H7BC	109.5
Br4B—Al3—Br2	111.17 (5)	H7BB—C7B—H7BC	109.5
Br3A—Al3—Br1	105.60 (19)	C3B—C8B—H8BA	109.5
Br4B—Al3—Br1	110.88 (6)	C3B—C8B—H8BB	109.5
Br2—Al3—Br1	109.71 (4)	H8BA—C8B—H8BB	109.5
Br3A—Al3—Br4A	127.9 (3)	C3B—C8B—H8BC	109.5
Br2—Al3—Br4A	104.55 (10)	H8BA—C8B—H8BC	109.5
Br1—Al3—Br4A	103.04 (10)	H8BB—C8B—H8BC	109.5
Br4B—Al3—Br3B	105.47 (14)	C4B—C9B—H9BA	109.5
Br2—Al3—Br3B	111.46 (7)	C4B—C9B—H9BB	109.5
Br1—Al3—Br3B	108.05 (7)	H9BA—C9B—H9BB	109.5
C2A—C1A—C5A	108.3 (2)	C4B—C9B—H9BC	109.5
C2A—C1A—C6A	127.0 (2)	H9BA—C9B—H9BC	109.5
C5A—C1A—C6A	124.7 (2)	H9BB—C9B—H9BC	109.5
C2A—C1A—Al1	70.94 (15)	C5B—C10B—H10A	109.5
C5A—C1A—Al1	69.83 (15)	C5B—C10B—H10B	109.5
C6A—C1A—Al1	126.8 (2)	H10A—C10B—H10B	109.5
C1A—C2A—C3A	108.3 (2)	C5B—C10B—H10C	109.5
C1A—C2A—C7A	126.8 (2)	H10A—C10B—H10C	109.5
C3A—C2A—C7A	125.0 (2)	H10B—C10B—H10C	109.5
C1A—C2A—Al1	70.62 (17)

C5A—C1A—C2A—C3A	0.1 (3)	C5B—C1B—C2B—C3B	0.4 (3)
C6A—C1A—C2A—C3A	177.9 (3)	C6B—C1B—C2B—C3B	−178.6 (2)
Al1—C1A—C2A—C3A	−60.0 (2)	Al2—C1B—C2B—C3B	60.89 (17)
C5A—C1A—C2A—C7A	−179.7 (3)	C5B—C1B—C2B—C7B	178.5 (2)
C6A—C1A—C2A—C7A	−1.9 (5)	C6B—C1B—C2B—C7B	−0.5 (4)
Al1—C1A—C2A—C7A	120.2 (3)	Al2—C1B—C2B—C7B	−121.0 (2)
C5A—C1A—C2A—Al1	60.1 (2)	C5B—C1B—C2B—Al2	−60.53 (17)
C6A—C1A—C2A—Al1	−122.2 (3)	C6B—C1B—C2B—Al2	120.5 (2)
C1A—C2A—C3A—C4A	−0.2 (3)	C1B—C2B—C3B—C4B	−0.9 (3)
C7A—C2A—C3A—C4A	179.6 (3)	C7B—C2B—C3B—C4B	−179.0 (2)
Al1—C2A—C3A—C4A	−60.6 (2)	Al2—C2B—C3B—C4B	59.97 (17)
C1A—C2A—C3A—C8A	−179.0 (3)	C1B—C2B—C3B—C8B	177.9 (2)
C7A—C2A—C3A—C8A	0.8 (5)	C7B—C2B—C3B—C8B	−0.1 (4)
Al1—C2A—C3A—C8A	120.5 (3)	Al2—C2B—C3B—C8B	−121.2 (3)
C1A—C2A—C3A—Al1	60.5 (2)	C1B—C2B—C3B—Al2	−60.88 (16)
C7A—C2A—C3A—Al1	−119.7 (3)	C7B—C2B—C3B—Al2	121.0 (3)
C2A—C3A—C4A—C5A	0.1 (3)	C2B—C3B—C4B—C5B	1.1 (3)
C8A—C3A—C4A—C5A	178.9 (3)	C8B—C3B—C4B—C5B	−177.7 (2)
Al1—C3A—C4A—C5A	−61.2 (2)	Al2—C3B—C4B—C5B	61.60 (16)
C2A—C3A—C4A—C9A	−179.7 (3)	C2B—C3B—C4B—C9B	178.2 (2)
C8A—C3A—C4A—C9A	−0.9 (5)	C8B—C3B—C4B—C9B	−0.6 (4)
Al1—C3A—C4A—C9A	118.9 (3)	Al2—C3B—C4B—C9B	−121.3 (3)
C2A—C3A—C4A—Al1	61.3 (2)	C2B—C3B—C4B—Al2	−60.49 (17)
C8A—C3A—C4A—Al1	−119.9 (3)	C8B—C3B—C4B—Al2	120.7 (3)
C3A—C4A—C5A—C1A	−0.1 (3)	C3B—C4B—C5B—C1B	−0.9 (3)
C9A—C4A—C5A—C1A	179.8 (3)	C9B—C4B—C5B—C1B	−178.0 (2)
Al1—C4A—C5A—C1A	−61.4 (2)	Al2—C4B—C5B—C1B	60.94 (17)
C3A—C4A—C5A—C10A	−177.8 (3)	C3B—C4B—C5B—C10B	178.9 (2)
C9A—C4A—C5A—C10A	2.1 (5)	C9B—C4B—C5B—C10B	1.8 (4)
Al1—C4A—C5A—C10A	120.9 (3)	Al2—C4B—C5B—C10B	−119.3 (2)
C3A—C4A—C5A—Al1	61.3 (2)	C3B—C4B—C5B—Al2	−61.82 (17)
C9A—C4A—C5A—Al1	−118.8 (3)	C9B—C4B—C5B—Al2	121.0 (3)
C2A—C1A—C5A—C4A	0.0 (3)	C2B—C1B—C5B—C4B	0.3 (3)
C6A—C1A—C5A—C4A	−177.8 (3)	C6B—C1B—C5B—C4B	179.2 (2)
Al1—C1A—C5A—C4A	60.76 (19)	Al2—C1B—C5B—C4B	−60.52 (17)
C2A—C1A—C5A—C10A	177.7 (3)	C2B—C1B—C5B—C10B	−179.5 (2)
C6A—C1A—C5A—C10A	−0.1 (5)	C6B—C1B—C5B—C10B	−0.5 (4)
Al1—C1A—C5A—C10A	−121.5 (3)	Al2—C1B—C5B—C10B	119.7 (2)
C2A—C1A—C5A—Al1	−60.8 (2)	C2B—C1B—C5B—Al2	60.83 (17)
C6A—C1A—C5A—Al1	121.4 (3)	C6B—C1B—C5B—Al2	−120.2 (3)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C7A—H7AA···Br3Bⁱⁱⁱ	0.98	3.03	3.886 (4)	146
C9A—H9AC···Br3A	0.98	3.04	3.773 (8)	133
C10A—H10E···Br3A	0.98	3.05	4.007 (7)	165
C9B—H9BB···Br1	0.98	2.95	3.770 (3)	141

Symmetry code: (iii) −x+2, −y+2, −z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C7A—H7AA···Br3Bⁱ	0.98	3.03	3.886 (4)	146.3
C9A—H9AC···Br3A	0.98	3.04	3.773 (8)	132.9
C10A—H10E···Br3A	0.98	3.05	4.007 (7)	165.1
C9B—H9BB···Br1	0.98	2.95	3.770 (3)	141.4

Symmetry code: (i) −x+2, −y+2, −z.

Footnotes

‡NREIP Intern at NRL.

Acknowledgements

We thank the Office of Naval Research for financial support. RJB wishes to acknowledge the NSF–MRI program (grant CHE-0619278) for funds to purchase the diffractometer.

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Volume 70| Part 3| March 2014| Pages m88-m89

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