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Title: Efficient Cp*Ir Catalysts with Imidazoline Ligands for CO 2 Hydrogenation: Cp*Ir Catalysts with Imidazoline Ligands for CO 2 Hydrogenation

Here, we report newly developed iridium catalysts with electron-donating imidazoline moieties as ligands for the hydrogenation of CO 2 to formate in aqueous solution. Interestingly, these new complexes promote CO 2 hydrogenation much more effectively than their imidazole analogues and exhibit a turnover frequency (TOF) of 1290 h –1 for the bisimidazoline complex compared to that of 20 h –1 for the bisimidazole complex at 1 MPa and 50 °C. Additionally, the hydrogenation proceeds smoothly even under atmospheric pressure at room temperature. The TOF of 43 h –1 for the bisimidazoline complex is comparable to that of a dinuclear complex (70 h –1, highest TOF reported) [Nat. Chem. 2012, 4, 383], which incorporates proton-responsive ligands with pendent-OH groups in the second coordination sphere. The catalytic activity of the complex with an N-methylated imidazoline moiety is much the same as that of the corresponding pyridylimidazoline analogue. Our result and the UV/Vis titrations of the imidazoline complexes indicate that the high activity is not attributable to the deprotonation of NH on the imidazoline under the reaction conditions.
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [1]
  1. National Inst. of Advanced Industrial Science and Technology (AIST), Tsukuba (Japan)
  2. Dalian Univ. of Technology, Panjin (China). School of Petroleum and Chemical Engineering
  3. Brookhaven National Lab. (BNL), Upton, NY (United States). Chemistry Dept.
Publication Date:
Report Number(s):
Journal ID: ISSN 1434-1948; R&D Project: CO026; KC0304030
Grant/Contract Number:
Accepted Manuscript
Journal Name:
European Journal of Inorganic Chemistry
Additional Journal Information:
Journal Volume: 2015; Journal Issue: 34; Journal ID: ISSN 1434-1948
ChemPubSoc Europe
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; homogeneous catalysis; Ir complex; CO2 hydrogenation
OSTI Identifier: