Highly efficient dimerization of ethylene by (imido)vanadium complexes containing (2-anilidomethyl)pyridine ligands: notable ligand effect toward activity and selectivity.

(Imido)vanadium(V) complexes containing the (2-anilidomethyl)pyridine ligand, V(NR)Cl(2)[2-ArNCH(2)(C(5)H(4)N)] (R = 1-adamantyl (Ad), cyclohexyl (Cy), phenyl), exhibit remarkably high catalytic activities (e.g. TOF = 2 730 000 h(-1) (758 s(-1)) by V(NAd)Cl(2)[2-(2,6-Me(2)C(6)H(3))NCH(2)(C(5)H(4)N)) for ethylene dimerization in the presence of MAO, affording 1-butene exclusively (selectivity 90.4 to >99%). The steric bulk of the imido ligand plays an important role in the selectivity (polymerization vs dimerization), and the electronic nature directly affects the catalytic activity (activity: R = Ad > Cy > Ph).