Synthesis and Structural Analysis of (Imido)Vanadium(V) Complexes Containing Chelate (Anilido)Methyl-imine Ligands: Ligand Effect in Ethylene Dimerization

A series
of (imido)vanadium dichlorido complexes containing chelate anionic
donor ligands of the type, VCl2(L)­(NR) [R = 1-adamantyl
(Ad), L = 2-(2,6-Me2C6H3)­NCH2(C9H6N) (2), 8-(2,6-Me2C6H3)­NCH2(C9H6N) (3); L = 2-(2,6-R′2C6H3)­NCH2(C5H4N),
R = 2-MeC6H4, R′ = Me (4a), iPr (4b); L = 2-(2,6-Me2C6H3)­NCH2(C5H4N), R = 4-MeC6H4 (5), 3,5-Me2C6H3 (6)], have been prepared
and identified. The reactions with ethylene by 2,3 in the presence of methylaluminoxane (MAO) afforded a mixture
of high molecular weight polyethylene and oligomers. Reactions with
ethylene by VCl2[2-(2,6-R′2C6H3)­NCH2(C5H4N)]­(NAd)
(1a,b), 4–6 afforded
1-butene with high selectivities (>92%), and the activities by 4a,b are at the same level as those in 1a,b. The activities by 5,6 were lower than 4a,b and were
at the same level of that by VCl2[2-(2,6-Me2C6H3)­NCH2(C5H4N)]­(NPh). These results thus suggest that both the chelate anionic
donor and the imido ligands play a role for both the activity and
the selectivity.