| abstract |
Zwitterionic transition metal cpds. of formula (I) are new. LnM?+-X-B-?-AR'm (I) L = pi -ligand or electron donor, opt. with two ligands L bonded together via a bridging gp. Z; M = gp. IIIb, IVb, Vb or VIb metal; X = hetero atom or hydrocarbon gp.; B = hydrocarbon gp.; A = gp. Ib, IIb, IIIa, IIIb, IVa, Va, Vb, VIb, VIIb or VIIIb metal; R<1> = perhalo-hydrocarbyl; n = 1,2,3 or 4 (n = 2 if M = a gp. IVb metal); m = 1,2,3,4 or 5. Also claimed is a process for the prodn. of (I) by reacting a cpd. of formula LnM(Hal)2 (II) (Hal = halogen) with a cpd. of formula <->X-B<-> (III) and then with a cpd. of formula AR<1>m. Also claimed is a process for the prodn. of olefin polymers by (co)polymerisation of olefin(s) in the presence of a catalyst contg. at least one cpd. (I). |