The Nature of the Barrier to Phosphane Dissociation from Grubbs Olefin Metathesis Catalysts

• DOI: 10.1002/ejic.201100932
• Publication Date: 2011-12-21T08:41:53Z
• Authors: Yury Minenkov; Giovanni Occhipinti; Wouter Heyndrickx; Vidar R. Jensen
• Keywords: Activation barrier; Salt metathesis reaction; Olefin Metathesis; Exergonic reaction

Abstract By using cost‐efficient density functional theory accounting for dispersion in combination with an implicit solvent model, the first time it has been possible to reproduce activation Gibbs free energies phosphane dissociation from Grubbs ruthenium olefin metathesis precatalysts solution good accuracy (mean unsigned error compared experiment <2.5 kcal mol –1 ). The barrier is calculated be range 17.8–25.7 a set of nine catalysts, and found located at intermediate Ru–P distances (ca. 4 Å). agreement experimental parameters gratifying suggests that calculations may give insight into these reactions and, particular, offer resolution as individual components barriers. forward (dissociation) barriers are much higher than corresponding reaction reverse reaction, binding, associated significant (13.2–15.6 latter mainly arises loss entropy solute–solvent interactions two fragments prior bond formation. Moreover, fact binding so means energy cannot taken identical or similar barrier, occasionally assumed earlier studies.