Vanadium Imido NHC Complexes for Ring-Closing Olefin Metathesis Reactions

Vanadium bis-phosphine imido and
oxo chloride alkylidenes have
been extensively applied in the ring-closing metathesis of various
acyclic olefins. However, their reactions involving ethylene have
shown limited productivity due to rapid decomposition. The primary
degradation pathway involving V bis-phosphine imido complexes is β-H
elimination at an unsubstituted metallacyclobutane. In contrast, β-H
elimination is disfavored for V oxo species, but bimolecular decomposition
precludes its high productivity. Herein, we present the synthesis
of V imido NHC complexes that are the most productive V catalysts
toward various terminal olefins in ring-closing metathesis reactions.
Experimental and computational studies suggest that β-H elimination
and bimolecular decomposition are disfavored for V imido NHC complexes.