| Autor: |
Syed ZH; Chemical Sciences and Engineering Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States., Kaphan DM; Chemical Sciences and Engineering Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States., Perras FA; U.S. DOE Ames Laboratory , Ames , Iowa 50011 , United States., Pruski M; U.S. DOE Ames Laboratory , Ames , Iowa 50011 , United States.; Department of Chemistry , Iowa State University , Ames , Iowa 50011 , United States., Ferrandon MS; Chemical Sciences and Engineering Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States., Wegener EC; Chemical Sciences and Engineering Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States., Celik G; Chemical Sciences and Engineering Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States., Wen J; Center for Nanoscale Materials , Argonne National Laboratory , Lemont , Illinois 60439 , United States., Liu C; Chemical Sciences and Engineering Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States., Dogan F; Chemical Sciences and Engineering Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States., Goldberg KI; Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States., Delferro M; Chemical Sciences and Engineering Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States. |
| Abstrakt: |
Single-site supported organometallic catalysts bring together the favorable aspects of homogeneous and heterogeneous catalysis while offering opportunities to investigate the impact of metal-support interactions on reactivity. We report a ( dm Phebox)Ir(III) ( dm Phebox = 2,6-bis(4,4-dimethyloxazolinyl)-3,5-dimethylphenyl) complex chemisorbed on sulfated zirconia, the molecular precursor for which was previously applied to hydrocarbon functionalization. Spectroscopic methods such as diffuse reflectance infrared Fourier transformation spectroscopy (DRIFTS), dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) spectroscopy, and X-ray absorption spectroscopy (XAS) were used to characterize the supported species. Tetrabutylammonium acetate was found to remove the organometallic species from the surface, enabling solution-phase analytical techniques in conjunction with traditional surface methods. Cationic character was imparted to the iridium center by its grafting onto sulfated zirconia, imbuing high levels of activity in electrophilic C-H bond functionalization reactions such as the stoichiometric dehydrogenation of alkanes, with density functional theory (DFT) calculations showing a lower barrier for β-H elimination. Catalytic hydrogenation of olefins was also facilitated by the sulfated zirconia-supported ( dm Phebox)Ir(III) complex, while the homologous complex on silica was inactive under comparable conditions. |
