ИСТИНА

Catalyst component for the polymerization of olefins comprising Mg. Ti and an electron donor belonging to mercaptoester derivatives of specific formula (I) in which Z is selected from C, Si, O, N, S or P with the proviso that the atoms O, S, P and N are not directly linked to either the carboxylic group or the sulphur atom of formula (I), the R2 groups, equal to or different from each other, are hydrogen or a C1-C20 hydrocarbon radicals, optionally containing a heteroatom selected from halogen, P, S, N,O and Si, which can be fused together to form one or more cycles, m is a number satisfying the valences of Z and n is an integer ranging from 1 to 10, X is O or S, Y is -OR3, -NR4R5) or R6 groups in which R1 and R3 are selected from C1-C15 hydrocarbon groups, optionally containing a heteroatom selected from halogen, P, S, N,O, and Si, R4-R5 groups, independently, are hydrogen or R1 groups and R6 groups have the same meaning as R1 groups.