A class of
metallocene compounds is disclosed having general formula (I) wherein Y is a
moiety of formula (II) wherein A, B, and D, same or different from each other, are selected from an element of the groups 14 to 16 of the
Periodic Table of the Elements (new IUPAC version), with the exclusion of
nitrogen and
oxygen; R<1>, R<2>, R<3>, R<4 >and R<5 >are
hydrogen or
hydrocarbon groups, Z is selected from a
moiety of formula (II) as described above and from a
moiety of formula (III) wherein R<6>, R<7>, R<8 >and R<9>, are
hydrogen or
hydrocarbon groups; L is a
divalent bridging group; M is an atom of a
transition metal selected from those belonging to group 3, 4, 5, 6 or to the
lanthanide or
actinide groups in the
Periodic Table of the Elements (new IUPAC version), X, same or different, is
hydrogen, a
halogen, a R<10>, OR<10>, OSO2CF3, OCOR<10>, SR<10>, NR<10>2 or PR<10>2 group, wherein the substituents R<10 >are hydrogen or
alkyl groups; p is an integer of from 1 to 3, being equal to the
oxidation state of the
metal M minus 2. The above metallocenes are particularly useful in the
polymerization of propylene.