Density functional theory studies of titanium-catalyzed hydroboration of olefins

The B3LYP method of density functional theory is used to study the hydroboration reaction of olefins catalyzed by Cp2Ti(HBcat'). The favorable pathway is where the active species Cp2Ti(HBcat') initially coordinates an olefin to form a structural intermediate having a five-membered ring with a Ti-H-B bridging unit. B-H bond cleavage then occurs to allow the reductive elimination to form alkylboronate ester as the main product. Calculations show that from the B-H cleavage species the beta-hydride elimination leading to the formation of side products, vinylboronate ester, is also competitive. Ti-O coordination is found to be the main reason for the lowering of the barrier of reductive elimination to form the main product, alkylboronate ester. The related olefin hydrogenation process has also been studied