Click the structures and reaction arrows in sequence to view the 3D models - no animations for these yetThis shows how hydrogenation can occur vis asymmetric activation of racemic TolBINAP-ruthenium complex. Either the S or R ruthenium-TolBINAP complex is unreactive with respect to hydrogenation of ketones. These have (S,S)-DPEN added to it to form monomeric ruthenium-TolBINAP-DPEN complexes. The R,SS cycles is preferred over the S,SS cycle.
Ryoji Noyori and Takeshi Ohkuma, Asymmetric Catalysis by Architectural and Functional Molecular Engineering: Practical Chemo- and Stereoselective Hydrogenation of Ketones, Angew. Chem. Int. Ed., 2001, 40, 40-73.