Confirmation of Bridging N-Indolides in 3-Methylindole and Di- and Tri(3-methylindolyl)methane Complexes of Dimethyl-, Diethyl-, and Diisobutylaluminum
摘要:
Reactions of 3-methylindole with one equivalent of R3Al produce the N-indolide-bridged dimers [(3-CH3C8H5N)AlR2](2) (R = Me (3a), Et (3b), Bu-i (3c)). NMR spectroscopy (H-1, C-13) demonstrates that compounds 3a, 3b, and 3c each exist in solution as a mixture of interconverting syn and anti isomers. Reactions of di(3-methylindolyl)methane or tri(3-methylindolyl)methane with one equivalent of Me3Al or Et3Al similarly produce the N-indolide-bridged compounds [(Ph)HC(3-CH(3)C(8)H(4)NA1R(2))(2)] (R = Me (4)) or [HC(3-CH3C8H4NAlR2)(3)] (R = Me (5a), Et (5b)), respectively. Reaction of tri(3-methyl-2-indolypmethane with one equivalent of (Bu3Al)-Bu-i yielded the N-indolide-bridged compound [HC(3-(CH3C8H4NAlBu2)-Bu-i)(2)(3-CH3C8H4NAl(H)Bu-i)] (6), apparently the result of beta-hydrogen elimination of isobutene from one isobutyl group per complex. The molecular structures of compounds 3a, 4, and 5a were determined by X-ray crystallography. Crystallographic data confirmed the presence of mu(2)-eta(1):eta(1)-N-3-methylindolide groups in each compound, the first examples of bridging N-indolide groups in compounds of the group 13 elements.