The Mechanism of Hydroamination of Allenes, Alkynes, and Alkenes Catalyzed by Cyclopentadienyltitanium-Imido Complexes: A Density Functional Study

Proton transfer from ammine or amide ligands to vinylamine-type π systems in intermediary titanacycles (see picture) of allene and alkyne hydroamination reactions is predicted by DFT model calculations. The weaker coordination of alkenes to the Ti=N fragment, the lack of a π system in the titanacycle, and thus the necessity of direct Ti−C bond protonation rationalize a higher barrier for alkene hydroamination.