Non-Precious Metal Catalysts for C-H Borylation Enabled by Metal-Metal Cooperativity.

Homogeneous catalysts for C-H functionalization typically require precious metals such as Pd, Ru, Rh, or Ir because of their facility in mediating two-electron redox mechanisms. Base metals such as Cu or Fe instead tend to undergo one-electron redox processes. By coupling together two base metal sites in a heterobimetallic catalyst design, base metal catalysts for photochemical C-H borylation were discovered. The optimal catalyst, (IPr)Cu- FeCp(CO)2, represents the first homogeneous catalyst for C-H borylation that contains no precious metals. Using metal-metal cooperativity in this way allows for base metal catalysts to replace precious metal catalysts while maintaining advantageous regioselectivity patterns. The proposed mechanism for heterobimetallic C-H borylation features bimetallic versions of classic organometallic reaction steps, serves as a guide for future catalyst designs, and opens the possibility for other precious metal transformations to be approached using metal-metal cooperativity as a design strategy. [ABSTRACT FROM AUTHOR]