. "The metallocene compound according to claim 1, wherein both Y and Z are a moiety of formula (II), A is an element of the group 16 of the Periodic Table of the Elements (new IUPAC version), B and D are carbon atoms, R1 is a C1-C20-alkyl group, R2 is hydrogen, R3 is different from hydrogen, m is 0, n and s are 1." . . . .