Influence of increasing steric demand on isomerization of terminal alkenes catalyzed by bifunctional ruthenium complexes

Preparation of a series of cyclopentadienyl- and imidazolyl-phosphine-containing Ru-based complexes bearing a different degree of the Cp-ring methylation has been attempted. According to experimental and structural data the steric factors prevented the formation of the last complex in the series that contains permethylated Cp ring. These complexes were then subjected to alkene isomerization using 1-hexene. The rate of isomerization decreased, in general, with the increase in the Cp-ring methylation suggesting that the initial alkene coordination and/or imidazolyl N decoordination steps are restricted in the overall mechanism.