Fast Proton Transfer and Hydrogen Evolution Reactivity Mediated by [Co₁₃C₂(CO)₂₄]⁴

A common approach to speeding up proton transfer (PT) by molecular catalysts is manipulation of the secondary coordination sphere with proton relays and these enhance overall reaction rates by orders of magnitude. In contrast, heterogeneous electrocatalysts have band structures that promote facile PT concerted with electron transfer (ET), known as the Volmer mechanism. Here, we show that [Co₁₃C₂(CO)₂₄]^4-, containing multiple Co-Co bonds to statistically enhance observed rates of PT, promotes PT on the order of 2.3 × 10⁹ M^-1 s^-1 which suggests a diffusion-limited rate. The fast ET and PT chemistry is attributed to the delocalized electronic structure of [Co₁₃C₂(CO)₂₄]^4-. Electrochemical characterization of [Co₁₃C₂(CO)₂₄]^4- in the presence and absence of protons reveals ET kinetics and diffusion behavior similar to other small clusters such as nanomaterials and fullerenes.