Hydrogenation of CO₂ by a Bifunctional PC(sp³)P Iridium(III) Pincer Complex Equipped with Tertiary Amine as a Functional Group

Reversible hydrogen storage in the form of stable and mostly harmless chemical substances such as formic acid (FA) is a cornerstone of a fossil fuels-free economy. In the past, we have reported a primary amine-functionalized bifunctional iridium(III)-PC(sp³)P pincer complex as a mild and chemoselective catalyst for the additive-free decomposition of neat formic acid. In this manuscript, we report on the successful application of a redesigned complex bearing tertiary amine functionality as a catalyst for mild hydrogenation of CO₂ to formic acid. The catalyst demonstrates TON up to 6×10⁴ and TOF up to 1.7×10⁴ h⁻¹. In addition to the practical value of the catalyst, experimental and computational mechanistic studies provide the rationale for the design of improved next-generation catalysts.