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-Dutyl-1,4-diazabutadiene, 1, with purified LiAl H4 (free from Al metal) in diethyl ether has been investigated in detail, a nd a range of products have been isolated. The lithium diamidoaluminum dihy dride [Li{N(t-Bu)CHCH2N-t-Bu}(2)AlH2], 2, the dimeric diamidoaluminum hydri de [cis-{[mu-N(t-Bu)CH2CH2N-t-Bu] AlH}(2)], 3, or the heteroleptic lithium tetraamidoaluminum species [(Et2O)Li{N(t-Bu)CH2}(2)(CHN-t-Bu)(2)Al], 4, can be selectively obtained depending on the order of addition or stoichiometr y of the reactants. We have rationalized these results in terms of the unst able 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(mu-H)(2)AlH2}(2)], 7, are described .