Organometallic catalysts containing hydrotris(pyrazolyl) borate and

Abstract

A catalyst composition is disclosed for catalyzing the polymerization and copolymerization reactions of ethylene monomers, with or without another olefin monomer. The catalyst composition comprises a metallocene compound represented by the the formula of (C.sub.5 R.sub.n H.sub.5-n)(L)MXY or the formula of (C.sub.5 R.sub.n H.sub.5-n)(L)MX.sup.+ A.sup.- ; wherein: (a) C.sub.5 R.sub.n H.sub.5-n is a substituted or unsubstituted cyclopendadienyl group; (b) L is tetrapyrazolyl borate, hydrotrispyrazolyl borate, dihydrotrispyrazolyl borate or hydrotris-3,5-dimethyl; (c) M is Group IIIB, Group IVB, or Group VB transitional metal; (d) X is a C.sub.1 to C.sub.4 alkyl or alkenyl group, an aromatic group, an alkylaryl, a halogen, a hydrogen, or a silane group; (e) Y, which can the same as or different from X, is a C.sub.1 to C.sub.4 alkyl or alkenyl group, an aromatic group, an alkylaryl, a halogen, a hydrogen, or a silane group; and (f) A.sup.- is non-coordinated or loosely coordinated bulky anion. Examples of the (C.sub.5 R.sub.n H.sub.5-n)(L)MXY and (C.sub.5 R.sub.n H.sub.5-n)(L)MX.sup.+ A.sup.- metallocene compounds are represented by the following formulas: ##STR1## respectively.