Backbone tuning in indenylidene–ruthenium complexes bearing an unsaturated N-heterocyclic carbene

Abstract

The steric and electronic influence of backbone substitution in IMes-based (IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene) N-heterocyclic carbenes (NHC) was probed by synthesizing the [RhCl(CO)2(NHC)] series of complexes to quantify experimentally the Tolman electronic parameter (electronic) and the percent buried volume (%Vbur, steric) parameters. The corresponding ruthenium–indenylidene complexes were also synthesized and tested in benchmark metathesis transformations to establish possible correlations between reactivity and NHC electronic and steric parameters.

Keywords

• N-heterocyclic carbene
• olefin metathesis
• percent buried volume
• ruthenium–indenylidene
• Tolman electronic parameter