Process for oligomerization of olefins that uses a catalytic composition that comprises an organometallic complex that contains a phenoxy ligand that is functionalized by a heteroatom

A process comprising catalytically oligomerizing olefins into compounds or into a mixture of compounds of formula CpH2p with 4≦p≦80, the catalyst being a catalytic composition comprising at least one organometallic complex of an element of group IV, which is titanium, zirconium or hafnium, wherein said organometallic complex contains at least one aryloxy ligand functionalized by a heteroatom, which is nitrogen, oxygen, phosphorus or sulfur or by an aromatic group, said organometallic complex having the following formula:

• [M(OAr)nY(4-n)]
• wherein:
• M is an element from group IV, which is titanium, zirconium, or hafnium,
• Y is an atom of chlorine, or bromine, or a hydrocarbyl radical that comprises 1 to 30 carbon atoms, or a radical, which is alkoxy R′O—, amido R′2N—, or carboxylate R′COO—, where R′ is a hydrocarbyl radical comprising 1 to 30 carbon atoms,
• n is an integer of 1 to 4,
• the ligand —OAr is an aryloxy ligand of the formula:
• in which:
• R2, R3, R4 and R5, identical or different, represent a hydrogen atom, a halogen, or a hydrocarbyl radical that comprises 1 to 30 carbon atoms,
• B is methoxy (—OMe), dimethylamino (—NMe2), or pyrrolidino, and A is —CH2—, —C(CH3)2— or —(CH2)2—.