Iodide‐Promoted Dehydrogenation of Formic Acid on a Rhodium Complex

Efficient and simple catalyst systems for dehydrogenation of formic acid (FA) to produce hydrogen are always desirable. In this work, the catalytic dehydrogenation of FA to H 2 and CO 2 by using the readily available [RhCp*Cl 2 ] 2 was found to be accelerated simply by the addition of halide anions, iodide being the most effective. At 60 °C, with [RhCp*Cl 2 ] 2 in azeotropic FA and triethylamine (TEA), the initial turnover frequency of dehydrogenation in the presence of I – (4375 h –1 ) is seven times as high as that of the reaction without additive (625 h –1 ). Preliminary mechanistic studies suggest that the dehydrogenation is turnover‐limited by the hydride‐formation step, which could be facilitated by the presence of I – .