metal-organic compounds
Triphenyl(tetrahydrofuran)aluminium(III)
aDepartment of Chemistry, National Chung Hsing University, Taichung 402, Taiwan
*Correspondence e-mail: hmgau@dragon.nchu.edu.tw
In the title compound, [Al(C6H5)3(C4H8O)], the Al atom has a distorted tetrahedral geometry. The C—Al—C angles range from 113.25 (7) to 116.27 (8)°, much larger than the O—Al—C angles, which range from 103.39 (7) to 103.90 (6)°. The tetrahydrofuran ring adopts an The crystal packing is stabilized by C—H⋯π interactions.
Related literature
For general background, see: Chen et al. (2007); Ku et al. (2007); Wu & Gau (2006). For related structures, see: Barber et al. (1982); De Mel & Oliver (1989); Jerius et al. (1986); Malone & McDonald (1967).
Experimental
Crystal data
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Refinement
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Data collection: SMART (Siemens, 1996); cell SAINT (Siemens, 1996); data reduction: SAINT; 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.
Supporting information
10.1107/S1600536808032091/ci2683sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536808032091/ci2683Isup2.hkl
A solution of phenylmagnesium bromide (90.0 mmol) in THF (50 ml) was slowly added to a solution of AlCl3 (4.00 g, 30.0 mmol) in THF (20 ml) at 273 K. The mixture was stirred at room temperature for 12 h and the solvent was removed under reduced pressure to afford a residue which was extracted with toluene (2 × 40 ml). The extracts were combined and concentrated to about 50 ml. Colourless crystals of the title compound (8.92 g, 90.0% yield) were obtained by cooling the concentrated solution at 273 K. The above synthetic procedures were conducted strictly under nitrogen atmosphere. 1H NMR (CDCl3, 400 MHz): δ 7.80–7.76 (m, 6H), 7.34–7.30 (m, 9H), 4.16 (m, 4H), 2.01 (m, 4H) p.p.m. 13C{1H} NMR (CDCl3, 100 MHz): δ 146.74, 137.99, 127.50, 127.06, 75.59, 24.97 p.p.m. Analysis calculated for C22H23OAl: C 79.97, H 7.02%;found: C 79.44, H 6.75%.
All H atoms were fixed geometrically [C—H = 0.93 Å or 0.97 Å] and treated as riding, with Uiso(H) = 1.2Ueq(C). The C atoms of the tetrahydrofuran ring display large displacement parameters, but no suitable
model for disorder was found.Data collection: SMART (Siemens, 1996); cell
SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); 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).Fig. 1. The molecular structure of the title compound with atom-numbering and displacement ellipsoids drawn at the 20% probability level. |
[Al(C6H5)3(C4H8O)] | F(000) = 704 |
Mr = 330.38 | Dx = 1.128 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 3804 reflections |
a = 9.649 (2) Å | θ = 2.1–26.0° |
b = 12.966 (3) Å | µ = 0.11 mm−1 |
c = 16.038 (4) Å | T = 293 K |
β = 104.210 (4)° | Block, colourless |
V = 1945.1 (8) Å3 | 0.58 × 0.42 × 0.21 mm |
Z = 4 |
Bruker SMART 1000 CCD diffractometer | 3804 independent reflections |
Radiation source: fine-focus sealed tube | 2971 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.023 |
ϕ and ω scans | θmax = 26.0°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −8→11 |
Tmin = 0.799, Tmax = 1.000 | k = −15→15 |
10682 measured reflections | l = −19→17 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.048 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.162 | H-atom parameters constrained |
S = 1.33 | w = 1/[σ2(Fo2) + (0.0861P)2] where P = (Fo2 + 2Fc2)/3 |
3804 reflections | (Δ/σ)max = 0.001 |
217 parameters | Δρmax = 0.27 e Å−3 |
0 restraints | Δρmin = −0.23 e Å−3 |
[Al(C6H5)3(C4H8O)] | V = 1945.1 (8) Å3 |
Mr = 330.38 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 9.649 (2) Å | µ = 0.11 mm−1 |
b = 12.966 (3) Å | T = 293 K |
c = 16.038 (4) Å | 0.58 × 0.42 × 0.21 mm |
β = 104.210 (4)° |
Bruker SMART 1000 CCD diffractometer | 3804 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 2971 reflections with I > 2σ(I) |
Tmin = 0.799, Tmax = 1.000 | Rint = 0.023 |
10682 measured reflections |
R[F2 > 2σ(F2)] = 0.048 | 0 restraints |
wR(F2) = 0.162 | H-atom parameters constrained |
S = 1.33 | Δρmax = 0.27 e Å−3 |
3804 reflections | Δρmin = −0.23 e Å−3 |
217 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Al1 | 0.39089 (5) | 0.69171 (4) | 0.18576 (3) | 0.0508 (2) | |
O1 | 0.38837 (12) | 0.75437 (10) | 0.29228 (7) | 0.0623 (4) | |
C1 | 0.27597 (17) | 0.56515 (13) | 0.18473 (11) | 0.0540 (4) | |
C2 | 0.2690 (2) | 0.51194 (15) | 0.25899 (13) | 0.0668 (5) | |
H2 | 0.3158 | 0.5394 | 0.3120 | 0.080* | |
C3 | 0.1956 (3) | 0.42013 (17) | 0.25735 (17) | 0.0818 (6) | |
H3 | 0.1936 | 0.3872 | 0.3086 | 0.098* | |
C4 | 0.1265 (2) | 0.37804 (17) | 0.1810 (2) | 0.0880 (7) | |
H4 | 0.0771 | 0.3162 | 0.1797 | 0.106* | |
C5 | 0.1296 (2) | 0.42674 (18) | 0.10597 (17) | 0.0836 (7) | |
H5 | 0.0820 | 0.3982 | 0.0536 | 0.100* | |
C6 | 0.2037 (2) | 0.51857 (15) | 0.10780 (13) | 0.0672 (5) | |
H6 | 0.2053 | 0.5503 | 0.0560 | 0.081* | |
C7 | 0.30029 (18) | 0.79599 (14) | 0.09920 (11) | 0.0573 (4) | |
C8 | 0.1554 (2) | 0.78994 (17) | 0.05675 (12) | 0.0699 (5) | |
H8 | 0.1016 | 0.7356 | 0.0700 | 0.084* | |
C9 | 0.0891 (2) | 0.8605 (2) | −0.00356 (15) | 0.0864 (7) | |
H9 | −0.0075 | 0.8535 | −0.0302 | 0.104* | |
C10 | 0.1641 (3) | 0.9404 (2) | −0.02443 (16) | 0.0907 (7) | |
H10 | 0.1195 | 0.9879 | −0.0658 | 0.109* | |
C11 | 0.3064 (3) | 0.95119 (19) | 0.01558 (16) | 0.0891 (7) | |
H11 | 0.3581 | 1.0065 | 0.0019 | 0.107* | |
C12 | 0.3729 (2) | 0.87933 (16) | 0.07661 (13) | 0.0728 (5) | |
H12 | 0.4694 | 0.8875 | 0.1032 | 0.087* | |
C13 | 0.59598 (17) | 0.66352 (14) | 0.19566 (12) | 0.0585 (4) | |
C14 | 0.6632 (2) | 0.68758 (18) | 0.13121 (16) | 0.0793 (6) | |
H14 | 0.6130 | 0.7237 | 0.0831 | 0.095* | |
C15 | 0.8054 (3) | 0.6587 (3) | 0.1368 (3) | 0.1220 (12) | |
H15 | 0.8478 | 0.6752 | 0.0924 | 0.146* | |
C16 | 0.8810 (3) | 0.6072 (3) | 0.2061 (4) | 0.1415 (18) | |
H16 | 0.9759 | 0.5898 | 0.2100 | 0.170* | |
C17 | 0.8176 (3) | 0.5803 (2) | 0.2712 (3) | 0.1196 (13) | |
H17 | 0.8686 | 0.5430 | 0.3183 | 0.144* | |
C18 | 0.6776 (2) | 0.60906 (17) | 0.26599 (15) | 0.0801 (6) | |
H18 | 0.6364 | 0.5916 | 0.3108 | 0.096* | |
C19 | 0.5018 (3) | 0.8175 (3) | 0.3436 (2) | 0.1160 (11) | |
H19A | 0.5475 | 0.8572 | 0.3066 | 0.139* | |
H19B | 0.5734 | 0.7742 | 0.3805 | 0.139* | |
C20 | 0.4384 (3) | 0.8856 (2) | 0.39505 (16) | 0.0958 (8) | |
H20A | 0.4383 | 0.9560 | 0.3745 | 0.115* | |
H20B | 0.4921 | 0.8834 | 0.4547 | 0.115* | |
C21 | 0.2920 (3) | 0.8503 (2) | 0.38737 (17) | 0.1015 (8) | |
H21A | 0.2860 | 0.8115 | 0.4381 | 0.122* | |
H21B | 0.2275 | 0.9087 | 0.3815 | 0.122* | |
C22 | 0.2540 (3) | 0.7853 (2) | 0.31139 (17) | 0.0937 (8) | |
H22A | 0.1952 | 0.8232 | 0.2634 | 0.112* | |
H22B | 0.2013 | 0.7253 | 0.3223 | 0.112* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Al1 | 0.0376 (3) | 0.0578 (3) | 0.0577 (3) | −0.00033 (19) | 0.0129 (2) | −0.0031 (2) |
O1 | 0.0481 (7) | 0.0751 (8) | 0.0667 (8) | −0.0054 (6) | 0.0197 (5) | −0.0148 (6) |
C1 | 0.0381 (8) | 0.0582 (10) | 0.0664 (10) | 0.0042 (7) | 0.0140 (7) | −0.0002 (7) |
C2 | 0.0603 (11) | 0.0681 (11) | 0.0727 (12) | 0.0086 (9) | 0.0174 (9) | 0.0077 (9) |
C3 | 0.0814 (15) | 0.0639 (12) | 0.1086 (17) | 0.0102 (11) | 0.0395 (13) | 0.0202 (12) |
C4 | 0.0677 (13) | 0.0540 (11) | 0.152 (2) | −0.0030 (10) | 0.0462 (15) | −0.0004 (14) |
C5 | 0.0645 (13) | 0.0739 (14) | 0.1074 (17) | −0.0091 (10) | 0.0115 (12) | −0.0236 (12) |
C6 | 0.0617 (11) | 0.0696 (12) | 0.0696 (11) | −0.0052 (9) | 0.0147 (8) | −0.0044 (9) |
C7 | 0.0494 (10) | 0.0637 (10) | 0.0604 (10) | 0.0024 (8) | 0.0166 (7) | −0.0036 (7) |
C8 | 0.0520 (11) | 0.0782 (13) | 0.0780 (13) | 0.0087 (9) | 0.0132 (9) | 0.0022 (10) |
C9 | 0.0616 (12) | 0.1058 (18) | 0.0869 (14) | 0.0202 (13) | 0.0090 (10) | 0.0061 (13) |
C10 | 0.0918 (17) | 0.0995 (17) | 0.0817 (14) | 0.0332 (14) | 0.0230 (12) | 0.0228 (12) |
C11 | 0.0990 (19) | 0.0791 (14) | 0.0950 (16) | 0.0011 (13) | 0.0351 (14) | 0.0210 (12) |
C12 | 0.0638 (12) | 0.0744 (12) | 0.0788 (12) | −0.0017 (10) | 0.0149 (9) | 0.0058 (10) |
C13 | 0.0416 (8) | 0.0606 (10) | 0.0736 (11) | −0.0031 (8) | 0.0149 (7) | −0.0177 (8) |
C14 | 0.0639 (12) | 0.0857 (14) | 0.0985 (15) | −0.0117 (10) | 0.0397 (11) | −0.0284 (12) |
C15 | 0.0816 (19) | 0.121 (2) | 0.192 (3) | −0.0240 (18) | 0.088 (2) | −0.069 (2) |
C16 | 0.0459 (14) | 0.126 (3) | 0.248 (5) | 0.0064 (16) | 0.027 (2) | −0.093 (3) |
C17 | 0.0632 (16) | 0.0994 (19) | 0.167 (3) | 0.0286 (14) | −0.0274 (18) | −0.054 (2) |
C18 | 0.0604 (12) | 0.0780 (14) | 0.0911 (14) | 0.0149 (10) | −0.0020 (10) | −0.0159 (11) |
C19 | 0.0805 (16) | 0.150 (3) | 0.124 (2) | −0.0434 (17) | 0.0365 (15) | −0.0780 (19) |
C20 | 0.115 (2) | 0.0881 (16) | 0.0816 (15) | −0.0032 (15) | 0.0194 (13) | −0.0192 (12) |
C21 | 0.125 (2) | 0.0909 (17) | 0.1067 (19) | 0.0074 (16) | 0.0622 (16) | −0.0156 (14) |
C22 | 0.0641 (13) | 0.122 (2) | 0.1058 (17) | −0.0033 (13) | 0.0421 (12) | −0.0335 (15) |
Al1—O1 | 1.8972 (13) | C11—C12 | 1.389 (3) |
Al1—C1 | 1.9783 (18) | C11—H11 | 0.93 |
Al1—C13 | 1.9800 (18) | C12—H12 | 0.93 |
Al1—C7 | 1.9809 (19) | C13—C14 | 1.384 (3) |
O1—C19 | 1.450 (2) | C13—C18 | 1.398 (3) |
O1—C22 | 1.460 (2) | C14—C15 | 1.404 (4) |
C1—C2 | 1.392 (3) | C14—H14 | 0.93 |
C1—C6 | 1.397 (3) | C15—C16 | 1.346 (5) |
C2—C3 | 1.382 (3) | C15—H15 | 0.93 |
C2—H2 | 0.93 | C16—C17 | 1.378 (5) |
C3—C4 | 1.357 (3) | C16—H16 | 0.93 |
C3—H3 | 0.93 | C17—C18 | 1.384 (4) |
C4—C5 | 1.365 (3) | C17—H17 | 0.93 |
C4—H4 | 0.93 | C18—H18 | 0.93 |
C5—C6 | 1.385 (3) | C19—C20 | 1.443 (3) |
C5—H5 | 0.93 | C19—H19A | 0.97 |
C6—H6 | 0.93 | C19—H19B | 0.97 |
C7—C12 | 1.384 (3) | C20—C21 | 1.461 (4) |
C7—C8 | 1.399 (2) | C20—H20A | 0.97 |
C8—C9 | 1.371 (3) | C20—H20B | 0.97 |
C8—H8 | 0.93 | C21—C22 | 1.452 (3) |
C9—C10 | 1.351 (4) | C21—H21A | 0.97 |
C9—H9 | 0.93 | C21—H21B | 0.97 |
C10—C11 | 1.372 (4) | C22—H22A | 0.97 |
C10—H10 | 0.93 | C22—H22B | 0.97 |
O1—Al1—C1 | 103.39 (7) | C11—C12—H12 | 118.9 |
O1—Al1—C13 | 103.90 (6) | C14—C13—C18 | 116.2 (2) |
C1—Al1—C13 | 113.25 (7) | C14—C13—Al1 | 122.74 (16) |
O1—Al1—C7 | 103.75 (7) | C18—C13—Al1 | 120.78 (16) |
C1—Al1—C7 | 114.23 (7) | C15—C14—C13 | 121.4 (3) |
C13—Al1—C7 | 116.27 (8) | C15—C14—H14 | 119.3 |
C19—O1—C22 | 108.11 (17) | C13—C14—H14 | 119.3 |
C19—O1—Al1 | 125.33 (13) | C14—C15—C16 | 120.6 (3) |
C22—O1—Al1 | 121.01 (12) | C14—C15—H15 | 119.7 |
C2—C1—C6 | 115.02 (17) | C16—C15—H15 | 119.7 |
C2—C1—Al1 | 123.27 (13) | C15—C16—C17 | 119.9 (3) |
C6—C1—Al1 | 121.56 (14) | C15—C16—H16 | 120.0 |
C3—C2—C1 | 122.9 (2) | C17—C16—H16 | 120.0 |
C3—C2—H2 | 118.6 | C18—C17—C16 | 119.6 (3) |
C1—C2—H2 | 118.6 | C18—C17—H17 | 120.2 |
C4—C3—C2 | 120.0 (2) | C16—C17—H17 | 120.2 |
C4—C3—H3 | 120.0 | C17—C18—C13 | 122.2 (3) |
C2—C3—H3 | 120.0 | C17—C18—H18 | 118.9 |
C3—C4—C5 | 119.8 (2) | C13—C18—H18 | 118.9 |
C3—C4—H4 | 120.1 | O1—C19—C20 | 107.6 (2) |
C5—C4—H4 | 120.1 | O1—C19—H19A | 110.2 |
C6—C5—C4 | 120.1 (2) | C20—C19—H19A | 110.2 |
C6—C5—H5 | 119.9 | O1—C19—H19B | 110.2 |
C4—C5—H5 | 119.9 | C20—C19—H19B | 110.2 |
C5—C6—C1 | 122.2 (2) | H19A—C19—H19B | 108.5 |
C5—C6—H6 | 118.9 | C19—C20—C21 | 107.3 (2) |
C1—C6—H6 | 118.9 | C19—C20—H20A | 110.3 |
C12—C7—C8 | 115.23 (18) | C21—C20—H20A | 110.3 |
C12—C7—Al1 | 123.50 (14) | C19—C20—H20B | 110.3 |
C8—C7—Al1 | 121.27 (15) | C21—C20—H20B | 110.3 |
C9—C8—C7 | 122.9 (2) | H20A—C20—H20B | 108.5 |
C9—C8—H8 | 118.6 | C22—C21—C20 | 107.0 (2) |
C7—C8—H8 | 118.6 | C22—C21—H21A | 110.3 |
C10—C9—C8 | 120.1 (2) | C20—C21—H21A | 110.3 |
C10—C9—H9 | 120.0 | C22—C21—H21B | 110.3 |
C8—C9—H9 | 120.0 | C20—C21—H21B | 110.3 |
C9—C10—C11 | 119.8 (2) | H21A—C21—H21B | 108.6 |
C9—C10—H10 | 120.1 | C21—C22—O1 | 106.4 (2) |
C11—C10—H10 | 120.1 | C21—C22—H22A | 110.5 |
C12—C11—C10 | 119.8 (2) | O1—C22—H22A | 110.5 |
C12—C11—H11 | 120.1 | C21—C22—H22B | 110.5 |
C10—C11—H11 | 120.1 | O1—C22—H22B | 110.5 |
C7—C12—C11 | 122.2 (2) | H22A—C22—H22B | 108.6 |
C7—C12—H12 | 118.9 |
D—H···A | D—H | H···A | D···A | D—H···A |
C16—H16···Cg1i | 0.93 | 2.78 | 3.654 (4) | 156 |
C19—H19A···Cg1ii | 0.97 | 2.81 | 3.600 (4) | 139 |
Symmetry codes: (i) x+1, y, z; (ii) −x+1, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | [Al(C6H5)3(C4H8O)] |
Mr | 330.38 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 9.649 (2), 12.966 (3), 16.038 (4) |
β (°) | 104.210 (4) |
V (Å3) | 1945.1 (8) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.11 |
Crystal size (mm) | 0.58 × 0.42 × 0.21 |
Data collection | |
Diffractometer | Bruker SMART 1000 CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.799, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10682, 3804, 2971 |
Rint | 0.023 |
(sin θ/λ)max (Å−1) | 0.618 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.048, 0.162, 1.33 |
No. of reflections | 3804 |
No. of parameters | 217 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.27, −0.23 |
Computer programs: SMART (Siemens, 1996), SAINT (Siemens, 1996), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
C16—H16···Cg1i | 0.93 | 2.78 | 3.654 (4) | 156 |
C19—H19A···Cg1ii | 0.97 | 2.81 | 3.600 (4) | 139 |
Symmetry codes: (i) x+1, y, z; (ii) −x+1, y+1/2, −z+1/2. |
Acknowledgements
This work was supported by a grant from the National Science Council of Taiwan (grant No. NSC 96-2113-M-005-007-MY3)
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Wu, K.-H. & Gau, H.-M. (2006). J. Am. Chem. Soc. 128, 14808–14809. Web of Science CrossRef PubMed CAS Google Scholar
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Triphenylaluminium was first reported 40 years ago and the solid-state study revealed a dimeric Al2Ph6 structure bridging through two phenyl groups (Malone & McDonald, 1967). For synthesis of monomeric triarylaluminium complexes, two synthetic strategies were used. The first route employed a reaction of dimesitylmercury with Al/HgCl2, furnishing three-coordinate trimesitylaluminium (Jerius et al., 1986) which possesses a trigonal planar structure. The second synthetic route used a strategy of providing an additional neutral ligand, such as tetrahydrofuran (THF) or diethyl ether (OEt2), giving four-coordinate monomeric AlAr3(L) complexes (L = THF or OEt2) (Barber et al., 1982; De Mel & Oliver, 1989). In addition to structural studies, organoaluminium reagents had been demonstrated as excellent nucleophiles in organic synthesis, owing to their higher reactivity and the Lewis acidity of the aluminium center. Recently, we reported applications of AlAr3(THF) in asymmetric aryl additions to aldehydes (Wu & Gau, 2006) and to ketones (Chen et al., 2007) and in coupling reactions (Ku et al., 2007). Due to their diversified applications in catalysis, we report herein the synthesis and structure of a four-coordinate triphenylaluminium compound, [Al(C6H5)3(OC4H8)].
The molecule of the title compound contains unsubstituted phenyl ligands and has a distorted tetrahedral geometry around the aluminium metal center (Fig. 1). The Al—O(THF) bond length of 1.8972 (13) Å is shorter by 0.08 Å than the Al—C bond distances of 1.9783 (18), 1.9800 (18) and 1.9809 (19) Å. This complex has similar Al—C bond distances with the four-coordinate (o-tol)3Al(OEt2) complex (Barber et al., 1982). The C—Al—O bond angles in the title complex [103.39 (7), 103.90 (6) and 103.75 (7)°] are much smaller than the C—Al—C bond angles [113.25 (7), 114.23 (7) and 116.27 (8)°]. In contrast, the bulky mesityl ligands in trimesityl(tetrahydrofuran)aluminium complex (De Mel & Oliver, 1989) repel each other, giving longer Al—C bond lengths of 2.011 (7), 2.020 (7) and 2.021 (6) Å. Similarly, the Al—O(THF) bond distance of 1.969 (5) Å in the above complex is longer by 0.07 Å than the Al—O(THF) bond length in the title compound.