| abstract |
A novel transition-metal compound having a bis-substituted cyclopentadienyl ligand of bridged structure (I) and a novel mixture of the compound (I) with an aluminoxane (B), each useful as catalyst component(s) for stereoregular olefin polymerization are provided, which compound (I) is expressed by the formula ##STR1## wherein M is Zr or Hf; Y is Si or Ge; R 1 n -C 5 H 4-n and R 1 q -C 5 H 4-q each represent an unsubstituted or substituted cyclopentadienyl group; n and q each represent an integer of 0 to 4, but cases of n=q=0 and n=q=4 are excluded; R 1 s may be same or different and each represent H, silyl or hydrocarbon radical; R 2 s may be same or different and represent H or hydrocarbon radical; and Xs may be same or different and represent H, halogen or hydrocarbon radical; and which aluminoxane is expressed by the formula (II) or the formula (III) ##STR2## wherein m represents an integer of 4 to 30 and R 3 represents a hydrocarbon radical. |