Dihydrogen activation by intermolecular rare-earth aryloxide/N-heterocyclic carbene Lewis pairs.

Dihydrogen was readily activated by combination of homoleptic rare-earth metal aryloxides, RE(OAr)3 (RE = La, Sm, and Y) with N-heterocyclic carbenes (NHCs) under mild conditions. RE(OAr)3 were found to be active catalysts for the reductive hydrogenation of NHCs to aminals under 1 bar of H2. In addition, the La/NHC pair also exhibited frustrated Lewis pair (FLP)-like reactivity towards carbon dioxide and phenylacetylene, affording 1,2-addition and deprotonation products, respectively.