A Molecular Iron Catalyst for the Acceptorless Dehydrogenation and Hydrogenation of N‑Heterocycles

A well-defined iron complex (3) supported by a bis­(phosphino)­amine
pincer ligand efficiently catalyzes both acceptorless dehydrogenation
and hydrogenation of N-heterocycles. The products from these reactions
are isolated in good yields. Complex 3, the active catalytic
species in the dehydrogenation reaction, is independently synthesized
and characterized, and its structure is confirmed by X-ray crystallography.
A trans-dihydride intermediate (4) is
proposed to be involved in the hydrogenation reaction, and its existence
is verified by NMR and trapping experiments.