N-Heterocyclic carbene group 4 transition metal catalysts: Synthesis and reactivity towards oligomerization/polymerization of α-olefins
Carbene ligands, esp. N-heterocyclic carbenes (NHC), are widely used in late transition metal catalysts, often enhancing catalytic activity due to their strong σ-donation ability helping to stabilize the active species. In contrast, limited examples of early transition metal catalysts contg. NHCs have been reported, esp. group 4 olefin polymn. catalysts, due to their poor binding affinity to early transition metals. Indeed, the increasing interest in "post-metallocene" catalysts for olefin polymn. has generated many active catalysts that exploit the modularity of the ligand to afford in particular interesting tacticity control. In this regard, we are investigating the use of tridentate dianionic carbenes bearing bisphenolate arms as ligands for olefin polymn. In this talk, we will present the coordination chem. of these new carbenes with group 4 metal complexes and their application as catalysts for the polymn./oligomerization of α-olefins.