Multinuclear Copper Hydride Complexes Supported by Polyphosphine Ligands

Copper hydride compounds have attracted interest in diverse fields as base metallic material in place of rare and noble metals, which have widely been utilized in hydrogenation catalysts, hydrogen storage, and electrochemical materials. Since the first report on the synthesis of copper hydride complex [Cu6H6(PPh3)6] in 1971, copper hydride reagents have been utilized in a variety of organic transformation. While well‐characterized copper hydride complexes have been long limited to a few examples, recently several research groups have reported the synthesis of phosphine‐stabilized copper hydride complexes with various metal‐frameworks and unique reactivity. Here we review recent progress on the synthesis and structures of copper hydride complexes supported by phosphine ligands, including di‐, tri‐, and tetraphosphines, and also describe their reactivity with CO2. Copper hydride complexes have attracted growing attention due to their diverse application as base metallic materials alternative to noble metals. This review presents an up‐to‐date overview of the synthesis and structure of copper hydride complexes supported by phosphine ligands. Their reactivity with CO2 is also discussed, including catalytic hydrogenation of CO2 by copper complexes.