Abstract: The invention provides a method for producing &agr;-olefin-aromatic vinyl compound copolymers of high quality at high productivity. The method for producing an &agr;-olefin-aromatic vinyl compound copolymer including copolymerizing an &agr;-olefin and an aromatic vinyl compound in the presence of a copolymerization catalyst formed of a transition metal compound component (A) and a co-catalyst component (B) wherein the component (A) employs a transition metal compound having two cross-linking groups wherein at least one of the cross-linking groups is a cross-linking group exclusively formed of a carbon-carbon bond.

Abstract: A novel double crosslinking type transition metal compound is herein disclosed which is represented by the general formula (I) wherein M is a metallic element in the groups 3 to 10 or a lanthanoide series of the periodic table; E1 and E2 are each a cyclopentadienyl group, an indenyl group or the like, and they form a crosslinking structure via A1 and A2; A1 and A2 are each a crosslinking group comprising a hydrocarbon group of one or more carbon atoms; X is a &sgr;-bonding ligand; and Y is a Lewis base. Also disclosed are a double crosslinking type biscyclopentadienyl derivative and bisindenyl derivative for use in the above-mentioned transition metal compound, its preparation process, a catalyst for olefin polymerization using the transition metal compound, and a preparation process of an olefin polymer by the use of this catalyst.

Abstract: A novel multiply crosslinked transition metal compound represented by the formula (I): wherein M is a metallic element of the Groups 3 to 10 or the lanthanide series of the Periodic Table; E1 and E2 are each a &sgr;-bonding or &pgr;-bonding ligand; X is a &sgr;-bonding ligand; Y is a Lewis base; A1, A2, . . . An and D are each a crosslinking group, and at least one of A1, A2, . . . An comprises a crosslink consisting of carbon alone; n is 2 to 4; p is 1 to 4; q is 1 to 5 and equal to the valence of M minus 2; r is 0 to 3; and s is 0 to 4, and a production process thereof. The transition metal compound is useful as a component of a polymerization catalyst for catalyzing the production of an olefin polymer having a uniform composition and a narrow molecular weight distribution in a high yield.

Abstract: The present invention is directed to a polymerization catalyst which comprises (A) a transition metal compound represented by the general formula (I)L.sub.d MX.sub.e Y.sub.f Z.sub.g (I)[wherein the respective symbols are as defined in the specification], (B) a compound capable of forming an ionic complex from the transition metal compound of the component (A) or its derivative and, if necessary, (C) an organic aluminum compound; and a process for preparing homopolymerizing or copolymerizing monomers in the presence of the above-mentioned polymerization catalyst. The polymerization catalyst of the present invention has a high activity at 70 to 200.degree. C. which is efficient in an industrial process or at a higher temperature and permits the formation of a (co)polymer which has a high molecular weight and a uniform composition and which can control a molecular weight distribution.

Abstract: A transition metal compound which is a multiple crosslinking type transition metal complex represented by the general formula (I) ##STR1## wherein M is a metallic element in the groups 3 to 10 or a lanthanoide series of the periodic table; E.sup.1 and E.sup.2 are each a .sigma.-bonding or a .pi.-bonding ligand; X is a .sigma.-bonding ligand; L is a Lewis base; A.sup.1, A.sup.2 . . . A.sup.n and D arc each a crosslinking group; n is 2 to 4; p is 1 to 4; q is 1 to 5; r is 0 to 3; and s is 0 to 4; and catalysts for olefin polymerization containing the transition metal compound or complexes thereof and a process for preparing an olefin polymer employing the catalyst.