Initiation stage of alkene metathesis: Insights from natural bond orbital and charge decomposition analyses

Abstract The Ru PR 3 bonds of 1 – 2 ( a - b )- PC , Ru CHPh bonds of 1a - b , 2 - Inact / Act and 1a - b , 2 - RCB were analyzed by charge decomposition (CDA) and natural bond orbital (NBO). We have found that the dissociation step of the Ru PR 3 bond is driven by charge transfer, while the RCB by polarization effects. Furthermore, the π(C ipso )–π*(Ru C) interaction was associated with delocalization effects in the benzylidene ring. Likewise, the nature of the rotameric changes in the carbene was studied through the resonance stabilization energy ( E NLW ). 2 presented a lower Δ E NLW (Inactive → Active) than 1a - b , which confirms that the delocalization effects are related to a low carbene rotameric energy.