Abstract: The invention concerns olefin polymerization catalyst component comprising an organometallic compound of general formula I wherein: M is a transition metal of groups 3, 4-10, lanthanide or actinide of the periodic table of the elements; each R is independently a structural bridge rigidly connecting two ligands L1, L2 and L3 and is constituted by 1 to 4 chain atoms selected from carbon, silicon, germanium, oxygen, boron; m, n and o are 0 or 1, with the proviso that m+n+o is 2 or 3; L1 is a ligand of the cyclopentadienyl type or is isolobal to cyclopentadienyl, L2 is a ligand of the cyclopentadienyl type or is isolobal to cyclopentadienyl, or a monovalent anionic ligand selected from the group consisting of N, P, B when m+n=2, it is selected from the group consisting of NR1, PR1, BR1, O and S when m+n=1; L3 is a monovalent anionic ligand selected from the group consisting of N, P, B when n+o=2, it is selected from the group consisting of NR1, PR1

Abstract: 1.