Electrochemical analysis of cyclopentadienylmetal carbonyl dimer complexes: Insight into the design of hydrogen-producing electrocatalysts

Four organometallic compounds of the type [Cp2M2(CO)n] (M = Fe, Ru, Mo, W) were evaluated electrochemically to probe the impact of variations in metal composition on ability to catalyze the deprotonation of weak acids, for the evolution of molecular hydrogen. The tungsten and molybdenum complexes undergo a less negative initial reduction, but provide no improvement for overpotential of dihydrogen evolution compared to iron when using 4-tert-butylphenol (pKa = 27.5) as a proton source Catalysis is thought to occur via protonation of the anions formed from the reduction of the dimers studied. The W-based anion catalyst represents the first example of a W-based organometallic hydrogen-producing electrocatalyst.