Crystal structure and quantum-chemical calculations of a tri­methyl­aluminium–THF adduct

The title compound, trimeth­yl(tetra­hydro­furan-κO)aluminium(III), is an addition product of tri­methyl­aluminium and tetra­hydro­furan (THF). Instead of a dimeric structure, which is very common for these types of compounds, a monomeric mol­ecular structure is observed.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.054
• wR factor = 0.152
• Data-to-parameter ratio = 24.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.75 Report
PLAT906_ALERT_3_C Large K Value in the Analysis of Variance ......      2.759 Check

Alert level G
PLAT072_ALERT_2_G SHELXL First  Parameter in WGHT  Unusually Large       0.10 Report
PLAT978_ALERT_2_G Number C-C Bonds with Positive Residual Density.          2 Info

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   2 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   2 ALERT level G = General information/check it is not something unexpected

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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Computing details

Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SIR2004 (Burla et al., 2007); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Trimethyl(tetrahydrofuran-κO)aluminium(III)

Crystal data

[Al(CH3)3(C4H8O)]	F(000) = 320
Mr = 144.18	Dx = 1.008 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 7.7034 (6) Å	Cell parameters from 8661 reflections
b = 9.1228 (7) Å	θ = 2.2–29.4°
c = 13.6833 (11) Å	µ = 0.15 mm^−1
β = 98.845 (8)°	T = 150 K
V = 950.18 (13) Å^3	Block, colourless
Z = 4	0.4 × 0.4 × 0.2 mm

Data collection

Oxford Diffraction Xcalibur Sapphire3 diffractometer	2071 independent reflections
Radiation source: Enhance (Mo) X-ray Source	1664 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.085
Detector resolution: 16.0560 pixels mm^-1	θmax = 27.0°, θmin = 2.7°
ω scans	h = −9→9
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010)	k = −11→11
Tmin = 0.767, Tmax = 0.971	l = −17→17
16552 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.054	H-atom parameters constrained
wR(F^2) = 0.152	w = 1/[σ^2(Fo^2) + (0.101P)^2 + 0.0468P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max = 0.001
2071 reflections	Δρmax = 0.89 e Å^−3
85 parameters	Δρmin = −0.32 e Å^−3
0 restraints

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.23608 (15)	0.37473 (13)	0.62125 (9)	0.0358 (3)
C1	0.4234 (2)	0.3761 (2)	0.61379 (15)	0.0403 (4)
H1A	0.4953	0.3839	0.6801	0.048*
H1B	0.4521	0.4592	0.5726	0.048*
C2	0.4549 (3)	0.2322 (2)	0.56601 (16)	0.0500 (5)
H2A	0.5778	0.1990	0.5853	0.060*
H2B	0.4284	0.2389	0.4930	0.060*
C3	0.3280 (3)	0.1316 (2)	0.60652 (16)	0.0507 (5)
H3A	0.3019	0.0440	0.5642	0.061*
H3B	0.3748	0.1000	0.6747	0.061*
C4	0.1680 (3)	0.2259 (2)	0.60476 (16)	0.0445 (5)
H4B	0.0906	0.2184	0.5401	0.053*
H4A	0.1006	0.1966	0.6576	0.053*
C5	0.2460 (3)	0.7005 (2)	0.65333 (15)	0.0439 (5)
H5A	0.3731	0.6915	0.6742	0.066*
H5B	0.2022	0.7858	0.6856	0.066*
H5C	0.2212	0.7130	0.5814	0.066*
C6	0.1905 (3)	0.4582 (2)	0.83000 (15)	0.0461 (5)
H6A	0.1225	0.3705	0.8410	0.069*
H6B	0.1635	0.5367	0.8742	0.069*
H6C	0.3162	0.4354	0.8438	0.069*
C7	−0.1208 (3)	0.5008 (2)	0.63514 (15)	0.0436 (5)
H7A	−0.1357	0.5156	0.5634	0.065*
H7B	−0.1902	0.5737	0.6648	0.065*
H7C	−0.1608	0.4021	0.6493	0.065*
Al1	0.12856 (7)	0.52245 (6)	0.69114 (4)	0.0335 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0322 (7)	0.0311 (6)	0.0447 (7)	−0.0050 (5)	0.0082 (5)	−0.0018 (5)
C1	0.0311 (9)	0.0408 (10)	0.0500 (11)	−0.0005 (7)	0.0088 (7)	0.0007 (8)
C2	0.0481 (11)	0.0471 (12)	0.0560 (13)	0.0081 (9)	0.0119 (9)	−0.0046 (9)
C3	0.0624 (14)	0.0336 (10)	0.0554 (13)	0.0024 (9)	0.0067 (10)	0.0011 (8)
C4	0.0451 (10)	0.0351 (10)	0.0535 (12)	−0.0111 (8)	0.0087 (8)	−0.0039 (8)
C5	0.0456 (11)	0.0368 (10)	0.0508 (12)	−0.0022 (8)	0.0117 (8)	0.0014 (8)
C6	0.0474 (11)	0.0526 (12)	0.0368 (10)	−0.0045 (9)	0.0021 (8)	0.0038 (8)
C7	0.0342 (10)	0.0541 (12)	0.0419 (11)	0.0013 (8)	0.0037 (8)	0.0035 (8)
Al1	0.0318 (3)	0.0352 (3)	0.0336 (3)	−0.0007 (2)	0.0048 (2)	0.00140 (19)

Geometric parameters (Å, º)

O1—C1	1.462 (2)	C3—C4	1.500 (3)
O1—C4	1.460 (2)	C5—Al1	1.9671 (19)
O1—Al1	1.9131 (13)	C6—Al1	1.976 (2)
C1—C2	1.503 (3)	C7—Al1	1.965 (2)
C2—C3	1.508 (3)
O1—C1—C2	104.49 (15)	C5—Al1—C6	116.43 (9)
C1—C2—C3	102.38 (16)	C5—Al1—C7	116.24 (9)
C4—C3—C2	102.87 (16)	C6—Al1—C7	114.97 (9)
O1—C4—C3	104.82 (15)	C1—O1—Al1	122.45 (10)
O1—Al1—C5	101.44 (7)	C4—O1—Al1	124.00 (11)
O1—Al1—C6	102.27 (8)	C4—O1—C1	109.40 (13)
O1—Al1—C7	101.92 (8)

Selected geometric parameters (Å, °).

O1–Al1		1.9131 (13)
C5–Al1		1.9671 (19)
C6–Al1		1.976 (2)
C7–Al1		1.965 (2)
C5–Al1–C6		116.43 (9)
C7–Al1–C5		116.24 (9)
C7–Al1–C6		114.97 (9)
C1–O1–Al1		122.45 (10)
C4–O1–Al1		124.00 (11)
C4–O1–C1		109.40 (13)