2381/40149 Zheng Wang Zheng Wang Xiangyang Chen Xiangyang Chen Bo Liu Bo Liu Qing-Bin Liu Qing-Bin Liu Gregory A. Solan Gregory A. Solan Xinzheng Yang Xinzheng Yang Wen-Hua Sun Wen-Hua Sun Cooperative interplay between a flexible PNN-Ru(II) complex and a NaBH4 additive in the efficient catalytic hydrogenation of esters University of Leicester 2017 Science & Technology Physical Sciences Chemistry, Physical Chemistry RUTHENIUM PINCER COMPLEXES TRANSITION-ELEMENTS CHIRAL ALCOHOLS REDUCTION METHANOL TRANSFORMATIONS ACTIVATION CARBONATES FORMATES BIOMASS 2017-08-10 15:34:27 Journal contribution https://figshare.le.ac.uk/articles/journal_contribution/Cooperative_interplay_between_a_flexible_PNN-Ru_II_complex_and_a_NaBH4_additive_in_the_efficient_catalytic_hydrogenation_of_esters/10208360 A catalyst loading of between 0.001–0.05 mol% of the PNN-bearing ruthenium(II) complex [fac-PNN]RuH(PPh3)(CO) (PNN = 8-(2-diphenylphosphinoethyl)amidotrihydroquinoline), in combination with 5 mol% NaBH4, efficiently catalyzes the hydrogenation of esters to their corresponding alcohols under mild pressures of hydrogen. Both aromatic and aliphatic esters can be converted with high values of TON or TOF achievable. Mechanistic investigations using both DFT calculations and labeling experiments highlight the cooperative role of NaBH4 in the catalysis while the catalytically active species has been established as trans-dihydride [mer-PNHN]RuH2(CO) (PNHN = 8-(2-diphenylphosphinoethyl)aminotrihydroquinoline). The stereo-structure of the PNHN-ruthenium species greatly affects the activity of the catalyst, and indeed the cis-dihydride isomer [fac-PNHN]RuH2(CO) is unable to catalyze the hydrogenation of esters until ligand reorganization occurs to give the trans isomer.