A metallocene compound is represented by the formula (1): ##STR00001## wherein: M is a Group 3, 4, 5 or 6 transition metal atom, or a lanthanide metal atom, or actinide metal atom, preferably a Group 4 transition metal atom selected from titanium, zirconium or hafnium; E is a substituted or unsubstituted monocyclic or polycyclic arenyl ligand pi-bonded to M; A is a substituted or unsubstituted polycyclic arenyl ligand that is pi-bonded to M and has a different ring structure than the E ligand; at least one of the A and E ligands includes at least one halogen substituent directly bonded to an sp.sup.2 carbon at a bondable ring position; Y is a bridging group containing at least one Group 13, 14, 15, or 16 element and any single position of the ring structure of A and to any single position of the ring structure of E; and y is zero or 1, indicating the absence (y=0) or presence (y=1) of Y; and each X is a univalent anionic ligand, or two X are joined and bound to the metal atom to form a metallocycle ring, or two X are joined to form a chelating ligand, a diene ligand, or an alkylidene ligand; provided that when E is an unsubstituted cyclopentadienyl ligand, either y is one or A is not 2-bromofluorenyl or 2,7-dibromofluorenyl.