Catalysts

Abstract

A complex of formula (I): (I') M is Hf; each X is a sigma ligand; L is a bridge of formula -(ER)—; y is 1 or 2; E is C or Si; each Ris independently a C-C-hydrocarbyl, tri(C-C-alkyl)silyl, C-C-aryl, C-C-arylalkyl or C-C-alkylaryl or L is an alkylene group such as methylene or ethylene; Ar and Ar′ are each independently an aryl or heteroaryl group optionally substituted by 1 to 3 groups Ror Rrespectively; Rand Rare each independently the same or can be different and are a linear or branched C-C-alkyl group, Carylalkyl, Calkylaryl group or Caryl group with the proviso that if there are four or more Rand Rgroups present in total, one or more of Rand Ris other than tert butyl; Rand Rare the same or are different and are a CH—Rgroup, with Rbeing H or linear or branched C-C-alkyl group, Ccycloalkyl group, Caryl group; each R is a —CH—, —CHRx- or C(Rx)- group wherein Rx is Calkyl and where m is 2-6; Ris a linear or branched C-C-alkyl group, Carylalkyl, Calkylaryl group or C-C-aryl group; Ris a C(R)group, with Rbeing a linear or branched C-Calkyl group; and Rand Rare the same or are different and are H or a linear or branched C-C-alkyl group. Invention relates also to a catalyst in solid form comprising (i) a complex of formula (I) and (ii) a cocatalyst of an aluminium compound and (iii) a cocatalyst of a boron compound.