The divergent effects of strong NHC donation in catalysis.

ABSTRACT: Strong σ-donation from NHC ligands (NHC = N-heterocyclic carbene) is shown to have profoundly conflicting consequences for the reactivity of transition-metal catalysts. Such donation is regarded as central to high catalyst activity in many contexts, of which the second-generation Grubbs metathesis catalysts (RuCl₂(NHC)(PCy₃)([double bond, length as m-dash]CHPh), GII) offer an early, prominent example. Less widely recognized is the dramatically inhibiting impact of NHC ligation on initiation of GII, and on re-entry into the catalytic cycle from the resting-state methylidene species RuCl₂(NHC)(PCy₃)([double bond, length as m-dash]CH₂), GIIm. Both GII and the methylidene complexes are activated by dissociation

SUBMITTER: Lummiss JAM 

PROVIDER: S-EPMC5947514 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature