Mechanistic Insights on the Controlled Switch from Oligomerization to Polymerization of 1-Hexene Catalyzed by an NHC-Zirconium Complex
The benzimidazolylidene zirconium complex 1 switches from an oligomerization (without additive) to a polymerization catalyst by addition of an L-type ligand such as trimethylphosphine, while larger phosphines or amines completely inhibit catalysis. On the basis of the regioselectivity of the oligomers/polymers obtained, the time profiles of reactions as a function of added ligand, and the molecular structures of several cationic zirconium complexes, we propose a mechanistic framework for interpreting this complex catalytic behavior.
Additional Information© 2015 American Chemical Society. Received: June 5, 2015; Published: August 17, 2015. Special Issue: Gregory Hillhouse Issue. This work was supported by grants from King Fahd University of Petroleum and Minerals (Dhahran, Saudi Arabia) and the USDOE Office of Basic Energy Sciences (Grant No. DE-FG03-85ER13431). The Bruker KAPPA 30 APEXII X-ray diffractometer was purchased via an NSFCRIF:MU award to the California Institute of Technology (CHE-0639094). A tribute to Greg Hillhouse, a warm and generous human being, a creative scholar, and self-proclaimed "favorite former postdoc" of J.E.B. Author Contributions: The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. The authors declare no competing financial interest.
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Supplemental Material - om5b00472_si_002.pdf