Abstract
In this study we have investigated computationally the origin of the cis-trans selectivity in the Ru-catalyzed cross metathesis (CM) of a prototype monosubstituted olefin, i.e., propene. Our calculations suggest that the origin of the preferential formation of trans-olefins is in the product release step, which prevents the initially formed cis-olefin from escaping the metal, and returns it to the reaction pool until the trans-olefin is formed.