The Rise of Manganese-Catalyzed Reduction Reactions

Abstract

Recent developments in manganese-catalyzed reducing transformations—hydrosilylation, hydroboration, hydrogenation, and transfer hydrogenation—are reviewed herein. Over the past half a decade (i.e., 2016-present), more than 115 research publications have been reported in these fields. Novel organometallic compounds and new reduction transformations have been discovered and further developed. Significant challenges that had historically acted as barriers for the use of manganese catalysts in reduction reactions are slowly being broken down. This review will hopefully assist in developing this research with a clear and concise overview of the catalyst structures and substrate transformations published so far.

Bis(N‐Heterocyclic Carbene) Manganese(I) Complexes: Efficient and Simple Hydrogenation Catalysts

“…More recently, many efforts focused on the replacement of noble-metals in such molecularly-defined catalysts by more abundant and cheaper 3d metals such as Mn, [5] Fe, [6] Co, [7] and Cu. [8] Especially Mn [9] attracted much scientific attention due to the limited knowledge of such complexes as hydrogenation catalysts. As shown in Figure 1, most of the reported systems rely on phosphine-based pincer ligands and include NÀ H or CÀ H acidic sites in the ligand-backbone according to the concept of bifunctional metal-ligand cooperativity.…”

Theory-guided development of homogeneous catalysts for the reduction of CO2to formate, formaldehyde, and methanol derivatives

“…While many catalytic systems facilitate the reduction to the formate level, those that overcome the kinetic barriers of further reduction to the formaldehyde and methanol levels are scarcer. 4 Furthermore, the overreduction of formaldehyde to methanol derivatives is difficult to suppress, and obtaining high selectivity for this important product level remains particularly challenging. 5…”

Electronic Structure of the Complete Series of Gas-Phase Manganese Acetylacetonates by X-ray Absorption Spectroscopy

“…Furthermore, transition-metal complexes are relevant for catalysis , while the attractiveness of transition-metal acetylonates in particular is based on the ability to chemically control their redox activity by coordination or de-coordination of the metal center . Among the 3d transition metals, manganese is well known as the main driver of the catalytic water splitting reaction mediated by the oxygen-evolving complex − and is relevant as a catalyst in other chemical synthesis reactions as it has access to a variety of oxidation states ranging from −3 to +7. − Thus, via the interplay of coordination and oxidation states of the manganese atom the properties of manganese acetylacetonate complexes can be tailored and controlled.…”