10.1021/acs.organomet.5b00727.s001 Huining Chai Huining Chai Tingting Liu Tingting Liu Qingfu Wang Qingfu Wang Zhengkun Yu Zhengkun Yu Substituent Effect on the Catalytic Activity of Ruthenium(II) Complexes Bearing a Pyridyl-Supported Pyrazolyl-Imidazolyl Ligand for Transfer Hydrogenation of Ketones American Chemical Society 2015 Substituent Effect NNN ligand order NHTs Catalytic Activity imidazolyl moiety 345 600 RuH complexes NMR TOF value transfer hydrogenation Transfer Hydrogenation 2015-11-09 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Substituent_Effect_on_the_Catalytic_Activity_of_Ruthenium_II_Complexes_Bearing_a_Pyridyl_Supported_Pyrazolyl_Imidazolyl_Ligand_for_Transfer_Hydrogenation_of_Ketones/2111248 Air- and moisture-stable ruthenium­(II) complexes bearing a multisubstituted pyrazolyl-imidazolyl-pyridine ligand were synthesized and structurally characterized by NMR and X-ray single-crystal crystallographic analyses. The substituents on the imidazolyl moiety of the NNN ligand exhibited a remarkable impact on the catalytic activity of the corresponding Ru­(II) complexes for transfer hydrogenation of ketones in refluxing 2-propanol, following the order NHTs > Me > H > NO<sub>2</sub>, to tune the catalytic activity. The highest final TOF value of 345 600 h<sup>–1</sup> was reached by means of 0.05 mol % of the Ru­(II)-NHTs-substituted NNN complex as the catalyst. The corresponding structurally confirmed RuH complexes are proposed as the catalytically active species.