An Aluminum Dihydride Working as a Catalyst in Hydroboration and Dehydrocoupling

摘要

The well-defined aluminum dihydride LAlH_2 (L = HC(CMeNAr)_2, Ar = 2, 6-Et_2C_6H_3) (1) operates in catalysis like a transition metal complex. The catalytic activity of 1 for hydroboration of terminal alkynes was investigated. Furthermore, catalyst 1 effectively initiated the dehydrocoupling of boranes with amines, thiols, and phenols, respectively, to form compounds with B-E bonds (E = N, S, O) under elimination of H_2. Quantum mechanical calculations indicate that hydroboration and dehydrocoupling reactions occur via three consecutive cycloaddition reactions involving the activation of the X-H (X = Al, B, C, and O) σ-bonds.