The reaction between CpRu(PPh3)2Cl and MeI results in quantitative halide exchange. The reaction is first order in each reactant with k40=8.7±0.3 x 10–5 s. We are considering four possible mechanistic pathways: a radical pathway, formation of MePh3PI followed by substitution, formation of a σ-complex of MeI, and oxidative addition of MeI. Two of these mechanisms can be ruled out experimentally. The radical pathway is unlikely due to an unchanged rate of reaction when a radical initiator is added. PPh3MeI is not soluble in toluene and leads to no reaction. However, the formation of a σ-complex and oxidative addition are difficult to distinguish experimentally, so computational methods (DFT) were applied. We report on the optimized structures of the proposed intermediates and the structures of the key transition states. Calculated activation energies, ΔG‡, will be discussed relative to the proposed mechanisms and kinetic data.

DFT exploration of halide exchange between CpRu(PPh3)2Cl and MeI

2019 Spring National Meeting

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