“Hidden” Metal–Ligand Cooperation for Additive‐Free Formic Acid Dehydrogenation

Abstract Formic acid (FA) is a promising hydrogen (H2) carrier for reversible hydrogen storage, combining a high storage capacity with safe transportation. Typically, the catalytic release of H2 from FA requires an external base, limiting the widespread use of FA as a H2 carrier in the hydrogen economy. Herein, we reveal an additive‐free FA dehydrogenation, catalyzed by a new ruthenium hydride complex, made possible with a tetradentate dad‐bis‐phosphine ligand. Experimental investigations were complemented by density functional theory (DFT) studies to elucidate the molecular mechanism of the process. The comparison of two distinct active species (κ2‐NN and η4‐NCCN coordination mode) by computational studies reveal the crucial role of the back bonding that facilitates FA dehydrogenation, originating from ligand–metal cooperation.