The Catalytic Transformation of Ethylene Using Chromium(III) Complexes with Bidentate Nitrogen-Containing Ligands

It has been shown that catalytic systems of the type Cr(III)/TEA/L, where Cr(III) is tris(2-ethylhexanoate)chromium(III) (Cr(EH)3), tris(acetylacetone)chromium(III) (Cr(acac)3); TEA is triethylaluminum; L is 2,2′-bipyridyne (bipy), 1,10-phenanthroline (Phen), N,N′-bis-(cyclohexyl)diazabutadiene-1,3 (DCy-DABD) and N,N′-bis-(2,6-diisopropylphenyl)diazabutadiene-1,3 (DPPh-DABD), can be employed for ethylene poly- and olygomerization at 60–80 °C and under pressure 2–3 MPa. The proton affinity of the used bidentate nitrogen-containing ligands is evaluated using quantum chemical calculations. The DCy-DABD, which has the lowest basicity, turns out to be the best ligand for the selective di- and trimerization of ethylene.