Formic Acid Dehydrogenation for Hydrogen Production Promoted by Grubbs and Hoveyda-Grubbs Catalysts†

In this work, we screened three Grubbs catalysts and two Hoveyda-Grubbs catalysts for the production of H by dehydrogenation of formic acid (FA). The best results were achieved with the use of a first-generation Hoveyda-Grubbs catalyst. With a catalyst loading of mere 0.5 μmol, a maximum TON of 36356 was obtained within 3 h. Two key intermediates were identified by using H NMR and high-resolution electrospray ionization mass spectroscopy (HRESI-MS), based on which a mechanism possibly responsible for the observed catalysis was proposed.