Dehydrogenation of Formic Acid Catalyzed by a Ruthenium Complex with an <i>N,N</i>′‑Diimine Ligand

We report a ruthenium complex containing an N,N′-diimine ligand for the selective decomposition of formic acid to H2 and CO2 in water in the absence of any organic additives. A turnover frequency of 12 000 h–1 and a turnover number of 350 000 at 90 °C were achieved in the HCOOH/HCOONa aqueous solution. Efficient production of high-pressure H2 and CO2 (24.0 MPa (3480 psi)) was achieved through the decomposition of formic acid with no formation of CO. Mechanistic studies by NMR and DFT calculations indicate that there may be two competitive pathways for the key hydride transfer rate-determining step in the catalytic process.本研究报道了一种含N,N′-二亚胺配体（N,N′-diimine）的钌配合物，可在无任何有机添加剂的水相体系中实现甲酸的选择性分解，生成氢气（H₂）与二氧化碳（CO₂）。在甲酸/甲酸钠水溶液中，于90 ℃条件下可达到12000 h⁻¹的转化频率（turnover frequency, TOF）以及350000的转化数（turnover number, TON）。通过该甲酸分解过程可高效制备高压氢气与二氧化碳，压力可达24.0 MPa（3480 psi），且无一氧化碳（CO）生成。经核磁共振（NMR）光谱与密度泛函理论（DFT）计算开展的机理研究显示，该催化过程中关键的氢转移决速步存在两条竞争性反应路径。