title: Feasibility of associative mechanism in enyne metathesis catalyzed by grubbs complexes.
abstract: The mechanism of enyne metathesis catalyzed by first and second generation Grubbs complexes has been computationally explored at the DFT level. The relative reactivity and the regioselectivity for the reaction of differently substituted alkenes and alkynes with model Ru complexes has been studied. The usually accepted dissociative mechanism for the alkene metathesis has been explored for alkynes, and compared with an associative pathway involving initial coordination of the alkyne to the 16-electron catalyst. Our results show that an associative mechanism would be the preferred pathway for the reaction of phosphine-based (first generation) Ru carbenes, at least for small phosphines such as PMe(3), whereas for the more reactive complexes containing a heterocyclic carbene as ligand (second generation catalysts), the dissociative process is far more favourable.
authors.affiliation: Departamento de Química Orgánica e Unidade Asociada ó CSIC, Facultade de Química, Universidade de Santiago, 15706 Santiago de Compostela, Spain.
authors.forename: Rebeca
authors.initials: R
authors.lastname: García-Fandiño
authors.forename: Luis
authors.initials: L
authors.lastname: Castedo
authors.forename: Juan R
authors.initials: JR
authors.lastname: Granja
authors.forename: Diego J
authors.initials: DJ
authors.lastname: Cárdenas