The Facile Synthesis of Exogenous Lewis-Base-Free Amidoalanes: A Structural Comparison.

A simple one-pot reaction of LiAlH(4), AlCl(3), and a secondary amine HNR(2) [R = Et, (i)Pr, (i)Bu, cyclo-C(6)H(11), (CH(2))(4), and (CH(2))(5)] in hydrocarbon solvents results in the formation of exogenous Lewis-base-free amidoalanes [H(2)Al(NR(2))](n) (n = 2 or 3) as crystalline solids (35-85% yield). In the solid state (seven X-ray structures), all the amidoalanes exist as dimers, with the exception of the pyrrolidine-derived alane which exists as a trimer. As solids, these amidoalanes exhibit significant kinetic stability towards oxygen/moisture allowing the brief (ca. 5 min.) handling of [H(2)Al(N(i)Pr(2))](2) in air.