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

Abstract Formic acid (FA) is a promising hydrogen (H 2 ) carrier for reversible hydrogen storage, combining a high storage capacity with safe transportation. Typically, the catalytic release of H 2 from FA requires an external base, limiting the widespread use of FA as a H 2 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 ( κ 2 ‐NN and η 4 ‐NCCN coordination mode) by computational studies reveal the crucial role of the back bonding that facilitates FA dehydrogenation, originating from ligand–metal cooperation.