Selective hydrogen generation from formic acid catalyzed by an iridium-azocarboxamide complex under neat conditions

A wide range of desirable properties has made formic acid (FA) a favored liquid organic hydrogen carrier in recent years. The state-of-the-art homogenous catalysts generally require a base as an additive in a certain solvent to promote FA dehydrogenation. However, it is crucially important to carry out the reaction without the use of a solvent or any volatile additive in order to achieve optimal efficiency in the process. Herein, we report a series of iridium compounds having an azocarboxamide ligand backbone capable of decomposing FA exclusively into H2 and CO2 without the need to use solvents or volatile additives. Under the optimized reaction conditions, a maximum TOF of 12,500 h^-1 was achieved with no formation of CO.