Cross-metathesis of dimethyl maleate and ethylene catalyzed by second generation ruthenium carbene complexes: B3LYP and MPW1K comparison study

The cross-metathesis of methyl maleate (2) and ethylene (10) using second generation Grubbs catalyst; (1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) (PCy3)CI2Rudouble bond; length as m-dashCHPh has been modeled at B3LYP/LACVP∗ and MPW1K/LACVP∗ levels of theory. Both models predict the metathesis of 2 to be viable kinetically and thermodynamically. The low reactivity of 2 in the metathesis reaction can be explained by the non-productive complex formation between carbonyl oxygen and Ru center that impedes the metathesis. Calculations show that the metathesis of ethylene is slightly endothermic process reflecting the relative stability of (1,3-dimesityl-4,5-dihydroimidazol-2-ylidene)CI2Rudouble bond; length as m-dashCHCOOMe catalyst due to additional stabilization of Ru center by sp2 or sp3 oxygen atoms. Although both models; B3LYP and MPW1K predict qualitatively similar picture of the metathesis; MPW1K functional seems to be superior to B3LYP in predicting the reaction energetics.