Next Generation Shilov Catalysis: Ligand Design and Computational Analysisfor Improved Catalysis in C-H Activation and Functionalization Chemistry.

[摘要] The activation and functionalization of C-H bonds has been a long standing goal in organometallic chemistry.The catalytic cycle involves three main catalytic steps: C-H activation, oxidation, and bond-forming reductive elimination.This work describes the combined use of computational analysis, ligand design, high-throughput screening, stoichiometric studies, and catalytic assays in an effort to achieve rational catalyst design.With recent advances in the field illustrating the use of in situ generated and decomposition susceptible cationic nitrogen based ligands, 2nd and 3rd generation stable and isolable bipyridine and pyridine-based ligands containing pyridinium substituents have been synthesized and fully characterized.With these ligands, catalysts based upon Pt, Pd, Rh, and Ir have been tested for C-H activation activity and compared against their neutral bipyridine and pyridine analogs.In all of these systems, the pyridinium substituent was found to have beneficial effects in catalyst activity for C-H activation through an H/D exchange assay with arene substrates.The Pd-based systems have also been utilized to achieve the catalytic C–H acetoxylation of aromatic substrates.The efficient use of potassium persulfate as a cheap stoichiometric oxidant has been achieved in these reactions (up to 73 turnovers), with the newly designed ligands key for achieving this reactivity.Computational studies have been employed to study the reductive elimination of coupling components which are traditionally difficult to achieve, Aryl-F and Aryl-CF3.Through these calculations, a novel mechanism for Aryl-carboxylate reductive elimination was discovered.

[发布机构] University of Michigan

[效力级别] C-H Functionalization

[关键词] C-H Activation;C-H Functionalization;Ligand Design;Catalyst Development;Computational;Chemistry;Science;Chemistry