Patent ID: 6927313

Claim:
A process for the selective oligomerization of ethylene to give essentially C 4 -C 8 α-olefins, characterized in that it is carried out in the presence of a catalytic system comprising the complex having general formula (II) (L)M(Y) n (II) wherein L represents the ligand having general formula (I) wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , the same or different, are selected from hydrogen, halogen, C 1 -C 10 alkyl, C 6 -C 15 aryl optionally halogenated, or adjacent pairs of R i groups (with i ranging from 1 to 6) are bound to each other to give cyclic hydrocarbon structures condensed with the thiophene or pyridine ring; R 7 is selected from H, C 1 -C 10 alkyl, C 6 -C 15 aryl; R 8 is selected from C 1 -C 10 alkyl and C 6 -C 15 aryl; M is a metal selected from transition metals, i.e. metals of groups 3 to 12 of the periodic table, and lanthanides; the above metal M being in oxidation state “s” positive different from zero, generally between 1 and 4; Y is selected from groups of an anionic nature bound to the metal as anion in ionic couple or with a covalent bond of the “σ” type; n expresses the number of Y groups sufficient for neutralizing the formal oxidation charge “s” of the metal M.