Structural analysis, dynamics and reactivity of Zr and Hf Salan complexes

Octahedral post-metallocene catalysts are rapidly gaining importance in olefin polymerization, mainly because of their facile synthesis and better performances at high temperature in comparison with metallocenes.[1] In contrast to stereorigid ansa-metallocenes,[2] post-metallocene precatalysts, upon activation, can form several isomers, some of which might be dormant or even inactive. Additionally, the active species can undergo in situ ligand modification or establish relatively fast equilibria with dormant/out-of-cycle species. Due to these phenomena, NMR studies to disclose the structure and dynamics of octahedral post-metallocenes catalysts are particularly challenging.[3] In this contribution, a thorough NMR study on the activation, speciation and dynamics of group IV Salan complexes will be reported.