Abstract: A process for polymerizing ethylene comprising contacting under polymerization condition ethylene and optionally one or more olefins with a catalyst system obtainable by contacting: a bis amido compound of formula (I) wherein Y is Si, Ge and Sn; X is hydrogen, halogen or an hydrocarbon radical; R1, R2, R3, R4, R5 and R6, are hydrocarbon radical; Q is a neutral Lewis base; and m is 0–2; one or more boron activating cocatalysts and one or more aluminum alkyls or alumoxanes.

Abstract: Catalysts for the polymerization of olefins are disclosed, which comprise the product obtained by contacting: (A) a bridged and/or substituted cyclopentadienyl compound of titanium, zirconium or hafnium; (B) an organometallic aluminium compound of the formula: Al(CH2—CR4R5—CR6R7R8)wR9qHz wherein R4 is a C1-C10 alkyl, alkenyl, or arylalkyl group; R5 is hydrogen or a C1-C10 alkyl, alkenyl, or arylalkyl group; R6 and R7 are C1-C10 alkyl, alkenyl, aryl, arylalkyl or alkylaryl groups; R8 is hydrogen or a C1-C10 alkyl, alkenyl, aryl, arylalkyl or alkylaryl group; R9 is a C1-C10 alkyl, alkenyl, or arylalkyl group, a carbon atom in the compound of formula (II) being optionally replaced by a Si or Ge atom; w is 1-3, z is 0 or 1, q=3−w−z, and (C) water; the molar ratio (B)/(C) being comprised between 1:1 and 100:1. These catalysts show an improved activity with respect to known catalysts, wherein different aluminium compounds are used.

Abstract: Process for the oligomerization of one or more olefinically unsaturated monomers comprising three or more carbon atoms, at least one of these monomers consisting of a C3 to C30 aliphatic mono-olefin, which process comprises reacting the olefinically unsaturated monomer(s) under oligomerization conditions in the presence of an effective amount of a catalyst system based on

Abstract: Catalysts for the polymerization of olefins are disclosed, comprising the product obtainable by contacting: (A) a bridged and/or substituted cyclopentadienyl compound of Ti, Zr or Hf; (B) one or more organometallic aluminium compounds of formula (II): AlR43−zHz wherein the substituents R4, same or different from each other, are linear or branched, saturated or unsaturated C1-C20 alkyl or alkylaryl radicals, optionally containing Si or Ge atoms, wherein at least one of the substituents R4 is different from a straight alkyl group; z is 0 or 1; and (C) water, the molar ratio between the organometallic aluminium compound and water being comprised between 1:1 and 100:1; said catalyst being obtainable by a process comprising the following steps: (i) contacting component (A) with part of component (B) in the absence of component (C); (ii) contacting part of component (B) with component (C) in the absence of component (A) and successively (iii) contacting the products obtained in steps (i) and (ii).

Abstract: Catalysts for the polymerization of olefins are disclosed, comprising the product obtainable by contacting: (A) a bridged and/or substituted cyclopentadienyl compound of Ti, Zr or Hf; (B) one or more organometallic aluminium compounds of formula (II): AlR 43−z Hz wherein the substituents R4, same or different from each other, are linear or branched, saturated or unsaturated C1-C20 alkyl or alkylaryl radicals, optionally containing Si or Ge atoms, wherein at least one of the substituents R4 is different from a straight alkyl group; z is 0 or 1; and (C) water; the molar ratio between the organometallic aluminium compound and water being comprised between 1:1 and 100:1; said catalyst being obtainable by a process comprising the following steps: (i) contacting component (A) with part of component (B) in the absence of component (C), (ii) contacting part of component (B) with component (C) in the absence of component (A) and successively (iii) contacting the products obtained in steps (i) and (ii).

Abstract: It is disclosed a new catalyst system, having high catalytic activity in the oligomerization of &agr;-olefins, comprising a bridged bis-amido Group 4 metal compound of formula (I): wherein M is Ti, Zr or Hf; Y is Si, Ge or Sn; X is a hydrogen, halogen or an hydrocarbon radical; R1, R2, R3, R4, R5 and R6 are hydrocarbon radicals, optionally containing Si, Ge, O, S, P, B or N atoms; Q is a neutral Lewis base; and m is 0-2; in association with a boron activating compound, and with one or more branched alkylaluminiums and/or alumoxanes of branched alkylaluminiums; said catalyst system allows oligomers to be obtained in high yields, with a high selectivity towards &agr;-oligomers.

Abstract: It is disclosed a new catalyst system, having high catalytic activity in the oligomerization of &agr;-olefins, comprising a bridged bis-amido Group 4 metal compound of formula (I): 1