Ligand-Induced Product Switching between 4‑Methyl-1-pentene and 2‑Methyl-1-pentene in Bis(imino)pyridine/V(III)-Catalyzed Propylene Dimerization: Cossee–Arlman Versus Metallacycle Mechanism

Ligand-induced product switching between 4-methyl-1-pentene (4M1P) and 2-methyl-1-pentene (2M1P) for propylene dimerization with a bis­(imino)­pyridine vanadium­(III) catalytic system was investigated using the combined density functional theory and DLPNO-CCSD­(T) method to determine which mechanism (metallacycle vs Cossee–Arlman) is most likely to be present. The calculations show that the Cossee–Arlman mechanism has low rate-determining energy barriers in comparison to the metallacycle mechanism. The NBO charge analysis supports that the electron-withdrawing/pushing substituents influence the process of the first propylene insertion, while the steric position of the ligand and vanadium affects the process of the second propylene insertion. The different substituents introduced to the backbone of the ligand changed the rate-determining step, which induced the switchable selectivity between 4M1P and 2M1P.