Brian Stephen Kimberley

NOVEL OLEFIN POLYMERIZATION CATALYSTS BASED ON IRON AND COBALT

A new family of olefin polymerization catalysts, derived from iron and cobalt complexes bearing 2,6-bis(imino)pyridyl ligands, is described.

Biaryl-bridged Schiff base complexes of zirconium alkyls: synthesis structure and stability

Abstract Three substituted salicylaldimine derivatives H2L1–3 of 2,2′-diamino-6,6′-dimethylbiphenyl give, under appropriate conditions, isolable alkyls of zirconium [ZrL1–3R2] (R=CH2Ph, CH2But). Two molecular structures confirm their cis-α geometry (C2-symmetric with cis alkyl ligands). They decompose via 1,2-migratory insertion of an alkyl group to imine, followed in some instances by a second similar reaction. The dimeric molecular structure of one such doubly-inserted product is presented. The kinetics of decomposition by this process are studied briefly, and it is noted that the rate increases with increased steric demand of the salicylaldimine unit.

Nucleophilic attack at pyridine nitrogen and its use to access a novel mono-anionic ligand for iron-based ethylene polymerisation catalystsElectronic supplementary information (ESI) available: further characterisation data for 2a–5a. See http://www.rsc.org/suppdata/cc/b2/b203805f/

Addition of MeLi to bis(imino)pyridines results in an unprecedented nucleophilic attack at pyridine nitrogen to afford novel mono-anionic [N,N,N] ligands: their treatment with FeCl3, followed by MAO activation, affords highly active ethylene polymerisation catalysts.

The surprisingly beneficial effect of soft donors on the performance of early transition metal olefin polymerisation catalysts

Group 4 metal complexes containing phenoxy-amide ligands bearing soft pendant donors are shown to give more highly active ethylene polymerisation catalysts than counterparts containing hard donors or systems without a pendant donor.

Problems and solutions for alkene polymerisation catalysts incorporating Schiff-bases; migratory insertion and radical mechanisms of catalyst deactivation

Steric blocking of an intramolecular 1,2-migratory insertion reaction of a zirconium salicylaldiminato complex leads to a long-lived catalyst for ethene polymerisation, but promotes a new radical catalyst decomposition mechanism in certain instances; kinetic and thermodynamic parameters for both pathways have been established.

High activity ethylene polymerisation catalysts based on chelating diamide ligands

Treatment of Zr(NMe2)4 with RNH(SiPh2)NHR and RNH(Me2SiCH2CH2SiMe2)NHR (R = 2,6-Me2C6H3) affords the four- and seven-membered chelate complexes {Zr[RN(SiPh2)NR](NMe2)2(HNMe2)} and {Zr[RN(Me2SiCH2CH2SiMe2)NR](NMe2)2} respectively; a dramatic effect of chelate ring size on ethylene polymerisation activity and kinetic profile is found.