Nova generació de catalitzadors de metàtesi d'olefines: la substitució de NHC per ilur de fosfoni

Abstract

Density functional theory calculations (DFT) have been used to describe the first turnover for olefin metathesis reaction of a new in silico family of homogenous Ru-based catalysts bearing a phosphoylide ligand with ethylene as a substrate. Equal to conventional Rubased catalysts for olefin metathesis that bear a N-heterocyclic carbene (NHC) ligand, the activation of these congeners occurs through a dissociative mechanism, with a more exothermic first phosphine dissociative step. However, predicted upper energy barriers were calculated to be on average ~5 kcal/mol less beneficial with respect to the Ru-NHC based catalysed metathesis. Overall, this present computational study emphasises on advantages of bidentate ligands to replace the NHC ligand of Ru-based metathesis and gives a potential recipe for the design of efficient Ru-based olefin metathesis catalysts. The new generation of catalysts is cationic, however the addition of a chloride instead of the phosphine seems to be favourable and with better performance in terms of both kinetics and thermodynamics