Published: April 7, 2020

The synthesis, characterization, and reactivity of group 4 organometallics supported by β ‐diketonates is reported. Sterically hindered β ‐diketonates, such as 2,6‐dimesitylbenzoyl pinacolone (L1 ) and 2,6‐dimesitylbenzoyl acetylmesitylene (L2 ), preclude the formation of tetrakis‐ and tris‐chelates, halting at cis ‐octahedrally coordinated M(Ln )2Cl2 (M = Ti, Zr, Hf; Ln L1 L2 ). Metathesis with benzylmagnesium chloride affords M(Ln )2Bn2 (M = Zr, Hf) and the reduced Ti(L1 )2Bn(THF) species. These are the first structurally‐characterized metal alkyl complexes exclusively supported by β ‐diketonates among the group 4 metals. Thermolysis of Zr(Ln )2Bn2 complexes results in unimolecular migratory insertion reaction, forming an enone by‐product and ZrO2. Combined Eyring analyses and computational investigations suggest the bond rearrangements are initiated by an initial benzyl migration reaction to the less hindered carbonyl group on the ligand. Activation of M(Ln )2Bn2 (M = Zr, Hf) in the presence of olefins resulted in similar oxygen abstraction. Implications and prospects for β ‐diketonate‐supported catalysis are discussed.