A metallocene compound is represented by the formula (1): AMX.sub.n-1 wherein M is a transition metal atom having a coordination number of n selected from Group 3, 4, 5 or 6 of the Periodic Table of Elements, or a lanthanide metal atom, or actinide metal atom; A is a substituted monocyclic or polycyclic arenyl ligand pi-bonded to M, wherein said arenyl ligand includes at least one halogen substituent directly bonded to any sp.sup.2 carbon atom at a bondable ring position of the ligand; and the or 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.