Iron: From Basic Chemistry to Modern C∙H Bond Functionalization Catalysts

Iron (Fe) is a first-row transition metal that offers several advantages, including low cost, Earth abundance, and environmental safety. These benefits are particularly significant compared to other transition metals from the second-row and beyond. Unlike precious metals such as palladium and platinum, iron is readily available, accessible, affordable, low in toxicity, and recyclable. This chapter aims to provide an overview of the importance of iron in various aspects of life and highlight the significant impact of iron catalysis. It begins by examining the occurrence of iron in nature and its importance to the environment and human health. The chapter then discusses iron compounds, focusing on their uses and applications in chemistry in general and organic synthesis in particular. This includes the role of iron compounds as catalysts and reagents in various organic synthetic transformations, such as electrophilic aromatic substitution reactions, cross-coupling reactions, cycloaddition reactions, and oxidation and reduction chemistries. The chapter also discusses developments in iron-catalyzed C∙H bond functionalization, including iron catalysts inspired by biological systems. It then continues by covering photocatalyzed C∙H bond functionalization. The chapter then highlights the importance of artificial intelligence and machine learning in catalyst design, which could be applied in iron catalysis. Given the green features of iron and iron catalysis, represented by Earth abundance, low cost, low toxicity, and recyclability, the chapter concludes with the role of iron catalysis in green chemistry and the preservation of the environment.