HYDROALUMINATION OF 1,4-DIAZABUT-1-ENES AND 4-LITHIO-1,4-DIAZABUT-1-ENES - SYNTHESIS OF AMIDOALUMINUM HYDRIDE, LITHIUM ALUMINUM-HYDRIDE, AND LITHIUM DIAMIDOALUMINUM HYDRIDE COMPLEXES

Treatment of the dimeric alkyl-substituted (E)-4-lithio-1,4-diazabut-1 -ene [cis-{Li[mu-N(t-Bu)CH(t-Bu)CHN(t-Bu)]}(2)], 1, With 2 equiv of Al H3 . NMe(3) results in hydroalumination yielding a tetrameric lithium diamidoaluminum hydride complex [{Li[N(t-Bu)CH(t-Bu)CH2N(t-Bu)]AlH2}(4 )], 4, which is associated through both mono- and dibridging hydrides forming a complex Li4Al2H6 12-membered macrocycle. Treatment of the (E )-1,4-diazabut-1-ene HN(t-Bu)CH(t-Bu)CHN(t-Bu), 2, with 2 equiv of AlH 3 . NMe(3) in hexane or 1 equiv of AlH3 in Et(2)O yields the monomeric internally coordinated secondary amine complexed aminoalane [{HN(t-Bu )CH(t-Bu)CH2N(t-Bu)}-AlH2], 5, which is stable with respect to loss of hydrogen under reflux in benzene. Treatment of 2 with LiAlH4 gives th e imine-secondary amine adduct 2 . LiAlH4, 3, which decomposes by hydr ometalation and metalation on heating to 120 degrees C in benzene to g ive 4. Compound 4 is not accessible via lithiation of 5 by MeLi in Et( 2)O. Crystals of 4 are triclinic, of space group <P(1)over bar> (No. 2 ), with a 15.664(6) Angstrom, b = 15.723(7) Angstrom c = 16.408(6) Ang strom, alpha = 69.65(3)degrees, beta = 84.98(3)degrees, gamma = 84.22( 3)degrees, V = 3763(3) Angstrom(3), and Z = 2. Crystals of 5 are monoc linic, of space group P2(1)/n (No. 14), with a = 9.426(9) Angstrom, b = 12.389(1) Angstrom, c = 15.42(1) A, beta = 103.04(4)degrees, V= 1754 (2) Angstrom(3), and Z = 4.