Catalyst useful for the polymerization of olefins

A transition metal compound having formula (I):

• ##STR8## wherein:
• M represents a transition metal selected from the group consisting of titanium, zirconium, and hafnium;
• two R.sup.1 s may be the same or different, and each represents a monovalent hydrocarbyl group having 1 to 4 carbon atoms or a monovalent hydrocarbyl group having 1 to 4 carbon atoms and containing silicon;
• R.sup.2 contains up to 20 carbon atoms and is selected from the group consisting of 1,3-butadienylene substituted with 1 to 2 alkyl groups and phenyl-1,3-butadienylene;
• R.sup.3 is selected from the group consisting of a methylene group, an ethylene group, and a silylene group which may be substituted by up to two groups selected from the group consisting of lower alkyl and phenyl;
• and
• X and Y independently represent a member selected from the group consisting of chlorine, lower alkyl, and a lower alkyl substituted silyl group,
• provided that the two five-membered cyclic ligands each having the substituents R.sup.1 and R.sup.2 are asymmetric about a plane containing M when viewed from their relative position in terms of the group R.sup.3, and
• said transition metal compound being useful as a catalyst component for polymerizing olefins.