A catalyst used for trimerization of ethylene into 1-hexene is descrobed, which
comprises (i) a specific organometallic complex having a neutral multidentate ligand
having a tripod structure, (ii) an alkylaluminoxane, and an optional ingredient
selected from: (iii) a halogenated inorganic compound, (iv) a specific alkyl group-containing
compound, (v) a combination of a halogenated inorganic compound with a specific
alkyl group-containing compound, (vi) an amine compound and/or an amide compound,
and (vii) a combination of an amine compound and/or an amide compound with a specific
alkyl group-containing compound.
