{2-[Bis(3-methyl-1H-indol-2-yl)meth­yl]phenolato-κO}dimeth­yl(tetra­hydro­furan-κO)aluminium(III)

Audrey C Eisenberg; Joseph M Tanski; Yutan D Y L Getzler

doi:10.1107/S1600536809040598

. 2009 Oct 13;65(Pt 11):m1353. doi: 10.1107/S1600536809040598

{2-[Bis(3-methyl-1H-indol-2-yl)methyl]phenolato-κO}dimethyl(tetrahydrofuran-κO)aluminium(III)

Audrey C Eisenberg ^a, Joseph M Tanski ^b, Yutan D Y L Getzler ^a,^*

PMCID: PMC2971370 PMID: 21578108

Abstract

The title compound, [Al(CH₃)₂(C₂₅H₂₁N₂O)(C₄H₈O)], was isolated as a minor component from a reaction mixture of the parent indolyl ligand and trimethylaluminum in tetrahydrofuran. The ligands adopt a distorted tetrahedral geometry around aluminium. Obvious hydrogen-bonding interactions are not present.

Related literature

For general background to (indolyl)methanes, see, see: Mason (2003 ▶); Mason et al. (2003 ▶). For related structures, see: Ziemkowska et al. (2007 ▶); Haddad et al. (2009 ▶). For patterns in hydrogen bonding, see: Steiner (2002 ▶).

Experimental

Crystal data

[Al(CH₃)₂(C₂₅H₂₁N₂O)(C₄H₈O)]
M _r = 494.59
Monoclinic,
a = 11.2045 (1) Å
b = 19.4191 (3) Å
c = 12.5543 (2) Å
β = 98.537 (1)°
V = 2701.32 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 115 K
0.30 × 0.25 × 0.20 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 1999 ▶) T _min = 0.969, T _max = 0.979
55902 measured reflections
9864 independent reflections
7340 reflections with I > 2σ(I)
R _int = 0.039

Refinement

R[F ² > 2σ(F ²)] = 0.051
wR(F ²) = 0.146
S = 1.04
9864 reflections
335 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.50 e Å⁻³
Δρ_min = −0.33 e Å⁻³

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2001 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: enCIFer (Allen et al., 2004 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809040598/pk2190sup1.cif

e-65-m1353-sup1.cif^{(26.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809040598/pk2190Isup2.hkl

e-65-m1353-Isup2.hkl^{(482.4KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected geometric parameters (Å, °).

Al—O1	1.7498 (9)
Al—O2	1.9097 (10)
Al—C9	1.9562 (16)
Al—C8	1.9588 (15)

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O1—Al—O2	99.27 (5)
O2—Al—C8	101.16 (6)
C9—Al—C8	121.34 (8)
C1—O1—Al	140.52 (8)

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Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2⋯N1	0.869 (13)	2.703 (15)	3.2353 (14)	120.8 (12)
N1—H1⋯N2ⁱ	0.874 (13)	2.734 (14)	3.5391 (15)	153.8 (14)

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work was generously supported by Kenyon College Startup Funds, Kenyon College Summer Science Scholars Program (ACE), the American Chemical Society’s Petroleum Research Fund (42880-GB 7) (YDYLG) and the National Science Foundation (CHE-0521237) (JMT).

supplementary crystallographic information

Comment

The molecule of the title complex (Fig. 1), has a distorted tetrahedral coordination geometry around aluminum with X—Al—X (X = C, O) angles ranging from 99.26 (5)° to 121.34 (8)°. The phenoxy(bisindolyl)methane ligand is coordinated to aluminum through a deprotonated phenol oxygen that is bent well out of the ideal sp³ to 140.50 (8)°, consistent with significant π-donation to Al(III) from the phenoxide O. In the crystal structure (Fig. 2), weak intramolecular N—H···N interactions may stabilize the ligand conformations while weak intermolecular N—H···N interactions may stabilize crystal packing. The distances of these contacts [2.703 (15) Å and 2.734 (14) Å, respectively] are quite long (Steiner, 2002). However, they are slightly less then the sum of the relevant Van der Waals radii.

Experimental

The ligand was synthesized by mixing two equivalents of 3-methylindole with one equivalent of salicylaldehyde in EtOH in the presence of an acid catalyst. The product was isolated by vacuum filtration (66.6%; mp 230–240 °C (dec.)); ¹H NMR (300 MHz, DMSO-d6), 2.01 (6H, s), 6.22 (1H, s), 6.76 (1H, dt, J=1.2 H, 8.5 Hz), 6.85 (1H, d, J=5.4 Hz), 6.91–7.03 (4H, m), 7.08 (2H, d, J=7.4 Hz), 7.30 (2H, d, J=7.2 H), 7.4 (2H, d, J=6.9 H), 9.58 (1H, s), 10.31 (2H, s); ¹³C NMR (75 MHz, DMSO-d6) 8.34, 34.79, 105.93, 111.07, 115.07, 117.57, 18.09, 119.06, 120.26, 127.22, 127.74, 128.85, 129.57, 134.72, 135.36, 154.69.

Using standard Schlenk techniques, the free ligand was dissolved in THF and AlMe₃ (2.0 M in heptane, 1 equivalent) was added dropwise via syringe. Upon reaction completion, solvent was removed under high vacuum and the residue was dissolved in a minimum of hot toluene. Upon sitting, a few small, colorless crystals appeared.