Narrow Results

The current demand for more sustainable catalytic processes has seen a clear shift from the classical noble-metal-based catalysts to cheaper and abundant metals. The focus on earth-abundant transition-metal-based catalysts has been marred by synthetic and characterization challenges but is ultimately achieving the desired catalytic results. To extract the catalytic potential of earth-abundant transition-metal-based complexes, great care concerning the design of the supporting ligands is required. Under certain conditions, monoanionic bidentate chelates present a good strategy to tackle those goals. The 2-iminopyrrolyl framework is a good example of that: Its huge electronic and steric tuning potential has paved the way for diverse coordination chemistries of first-row transition metals, from manganese to copper. With such metal complexes in hand, several catalytic applications have been studied, namely polymerization, hydrofunctionalization and click chemistry. This chapter features the main catalytic achievements of complexes of earth-abundant metals bearing 2-iminopyrrolyl ligands and their respective mechanistic insights and structure–reactivity relationships.

The catalytic functionalization of C–H, C–OH and C–C bonds belongs to the most important processes in nature and the industry. In nature, this process occurs via involvement of enzymes, effectively and selectively, usually with very high turnover numbers. The pivotal role in enzymatic activity is played by the metal center cofactors, which involve several bioavailable transition metals, such as, iron, copper, manganese and zinc. In the industry, bond functionalization requires the presence of metal catalysts; therefore, a bio-inspired design of metal catalysts is a challenging approach. The recent advances in the catalysis of industrially important reactions, namely the oxidation and hydrocarboxylation of alkanes, the oxidation of alcohols and C–C coupling are reported. Convenient, environmentally friendly methods are presented, and the role and efficacy of the various transition-metal (iron, copper, zinc, manganese, nickel, vanadium, palladium and cobalt) catalysts are explored.