Base Metal Catalyst for Indirect Hydrogenation of CO2

We herein report a novel Mn-SNS-based catalyst, which is capable of performing indirect hydrogenation of CO₂ to methanol via formylation. In this domain of CO₂ hydrogenation, pincer ligands have shown a clear predominance. Our catalyst is based on the SNS-type tridentate ligand, which is quite stable and cheap as compared to the pincer type ligands. The catalyst can also be recycled effectively after the formylation reaction without any significant change in efficiency. Various amines including both primary and secondary amines worked well under the protocol to provide the desired formylated product in good yields. The formed formylated amines can also be reduced further at higher pressures of hydrogen. As a whole, we have developed a protocol that involves indirect CO₂ hydrogenation to methanol that proceeds via formylation of amines.