Carboxylate as a Non-innocent L-Ligand: Computational and Experimental Search for Metal-Bound Carboxylate Radicals.

We show that the carboxylate radical acts as an L-ligand with certain high-spin transition metal centers. Such coordination preserves the O-radical character needed for C-H activation via hydrogen atom transfer. Capture of the new C-radical by the metal and subsequent reductive elimination leads to formal C-H acyloxylation. Decarboxylation of the RCO 2 radical is minimized through hybridization effects introduced by spiro-cyclopropyl moiety.