Aluminum Hydride Cations Stabilized by Weakly Coordinating Carbaalanates

The reactions of t-BuC⋮CLi with a mixture of AlH3·NMe3 and ClAlH2·NMe3 in boiling toluene with the addition of [t-BuCH2(Bzl)NMe2]Cl, or a bulky β-diketimine instead, and [n-Bu4N]Cl led to the carbaalanates [H2Al(NMe3)2]2[(AlH)8(CCH2t-Bu)6], 3, and [n-Bu4N]2[(AlH)8(CCH2t-Bu)6], 4, respectively. The reaction of Me3N·Al(C⋮Ct-Bu)3 5 and AlH3·NMe3 in boiling toluene yielded [H(n-Bu)Al(NMe3)2][(AlH)7(AlNMe3)(CCH2t-Bu)6], 6, in trace amounts. The single-crystal X-ray structures of 3 and 6 are reported. The compounds 3, 4, and 6 consist of well-separated ion pairs introducing carbaalanates as weakly coordinating anions and stabilizing aluminum hydride cations.