From Ruthenium to Iron and ManganeseA Mechanistic View on Challenges and Design Principles of Base-Metal Hydrogenation Catalysts

The development of new homogenous base-metal catalysts for hydrogenation reactions is a rapidly expanding and evolving field of research, which has the potential to provide inexpensive and sustainable alternatives for atom economic reactions and possibly contribute additional tools for hydrogen storage applications. While tremendous accomplishments in terms of catalytic activity and substrate scope have been reported over the last years, the available mechanistic information on these reactions is often very limited. The current Concept article intends to summarize, categorize and analyze mechanistic information on iron-based hydrogenation catalysts. In addition, we present the challenges that must be tackled in the future to develop more effective and mature catalyst systems. The primary focus of this work lies on iron-based catalysts. However, manganese-based hydrogenation catalysts have recently attracted significant interest and a remarkable progress in their development has been made. Available mechanistic information on manganese catalysts is compared to that on iron catalysts and basic similarities and differences are discussed.