DUGi

Olefin Metathesis with Ru-Based Catalysts Exchanging the Typical N-Heterocyclic Carbenes by a Phosphine–Phosphonium Ylide

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@2072@@282203

Density functional theory (DFT) calculations have been used to describe the first turnoverof an olefin metathesis reaction calling for a new in silico family of homogenous Ru-based catalystsbearing a phosphine–phosphonium ylide ligand, with ethylene as a substrate. Equal to conventionalRu-based catalysts bearing an N-heterocyclic carbene (NHC) ligand, the activation of these congenersoccurs through a dissociative mechanism, with a more exothermic first phosphine dissociation step.In spite of a stronger electron-donating ability of a phosphonium ylide C-ligand with respect to adiaminocarbene analogue, upper energy barriers were calculated to be on average ca. 5 kcal/molhigher than those of Ru–NHC standards. Overall, the study also highlights advantages of bidentateligands over classical monodentate NHC and phosphine ligands, with a particular preference forthe cis attack of the olefin. The new generation of catalysts is constituted by cationic complexespotentially soluble in water, to be compared with the typical neutral Ru–NHC ones

Albert Poater thanks the Spanish Ministry of Economy and Competitiveness (MINECO) for a project CTQ2014-59832-JIN and Xarxa de Química Teòrica i Computacional for a VALCHEM2016 project

Molecular Diversity Preservation International (MDPI)