The Reaction of LiAlH4 with 1,4-Di-tert-butyl-1,4-diazabutadiene: Imine-Containing Aluminum Hydrides Stabilized by Lithium Coordination

The reaction of 1,4-di-tert-butyl-1,4-diazabutadiene, 1, with purified LiAlH(4) (free from Al metal) in diethyl ether has been investigated in detail, and a range of products have been isolated. The lithium diamidoaluminum dihydride [Li{N(t-Bu)CHCH(2)N-t-Bu}(2)AlH(2)], 2, the dimeric diamidoaluminum hydride [cis-{[-N(t-Bu)CH(2)CH(2)N-t-Bu]AlH}(2)], 3, or the heteroleptic lithium tetraamidoaluminum species [(Et(2)O)Li{N(t-Bu)CH(2)}(2)(CHN-t-Bu)(2)Al], 4, can be selectively obtained depending on the order of addition or stoichiometry of the reactants. We have rationalized these results in terms of the unstable adducts which are likely to be present in solution at low temperature. The X-ray crystal structures of 2 and the dimeric lithium aluminum hydride adduct [{[HN(t-Bu)CH(t-Bu)CHN-t-Bu]Li(-H)(2)AlH(2)}(2)], 7, are described.