Catalysts compositions for the polymerization and copolymerization of alpha-olefins

The invention relates to a polymerization catalyst system, a polymerization process using that catalyst system and polymers produced therefrom. The catalyst system results from the combination of a co-catalyst and a bridged 3-substituted-indenyl metallocenes of formula (I) wherein M is Ti, Zr or Hf, R 1 is an indenyl ligand; R 2 and R 3 bonded to R 1 at position 3 are, independently, H or a monovalent organic radical; R 2 ' and R 3' bonded to R 1 at position 2 are, independently, hydrogen or a monovalent organic radical; wherein at least one of R 2 and R 3 is a monovalent organic radical; Q is a divalent group and X 1 and X 2 are monovalent ligands, its racemic or meso stereoisomers and mixtures thereof. Polymers made with said polymerization catalyst system can have from narrow to broad molecular weight distribution (MWD) or from narrow bimodal MWD to broad bimodal MWD and melt indexes from about 0 to about 25 without the need of using molecular weight regulators by properly selecting the indenyl substituent (size and number of substituents) and the form used (pure stereoisomers of mixtures thereof).