Patent ID: 7371802

Claim:
A solid catalyst component for the polymerization of olefins comprising Mg, Ti, halogen and an electron donor selected from thiophene derivatives of formula (I): wherein R is a branched alkyl group, R 1 , R 2 and R 3 , same or different, are hydrogen, halogen, R 4 , OR 4 , COOR 4 , SR 4 , NR 4 2 or PR 4 2 , wherein R 4 is a linear or branched C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 3 -C 20 cycloalkyl, C 6 -C 20 aryl, C 7 -C 20 alkylaryl or C 7 -C 20 arylalkyl group, optionally containing at least one heteroatom, and at least two of said R 1 -R 3 groups can also be joined to form a cycle, with the proviso that at least one of R 1 and R 2 is COOR 4 and that when R 2 is COO-i-octyl and R is i-octyl, at least one of R 1 and R 3 are different from hydrogen.