The Design of Non-Metallocene Analogues as Polymerization Catalysts

Abstract

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The main aim of this project was to prepare novel "non-metallocene" complexes and to testtheir ability to act as catalysts for the polymerisation of ethylene. To do this, firstly, two new polyamine ligands, 1,4-bis(2-aminophenyl)piperazine L2 and 1,7-bis(2-aminophenyl)-I,4,7,lO-tetraazacyc1ododecane L5 have been prepared and fully characterised. A preliminary investigation into the co-ordination chemistry of these potentially tetra-and hexa-dentate ligands with first row transition metals, such as Ti, Zr and Nb have been studied. L2 has been silylated at the aniline nitro gens by treatment with n-BuLi and Me3SiCI to give1,4-bis(2-trimethylsilylaminophenyl)piperazine L3 in good yield. The co-ordination of L3, as it's dianion, with TiCI4, ZrCla.Zthf and NbC14.2thf has been investigated. However, no tractablemetal complex was formed with Ti(IV), while the Zr and Nb systems resulted in the eliminationofMe3SiCI in solution and deposition ofL2, as shown by IH_NMR. Secondly, with the aim of testing suitable oxalic amidine 'non-metallocene' type catalyst systemto use with co-catalysts of methylaluminoxane (MAO) and selected Lewis acids, in polymerizationof ethylene has been studied. The oxalic amidine ligand C6HSN=C( NHtBu)-C( NHtBu )=NC6HS L6 and CJlsN=C[NCBu)(SiMe3)]-C[NCBu)(SiMe3)]=NC6Hs L7 are described. Treatment of L6 with Ti(NMe2)4gives bimetallic complex of [Ti(NMe2)3.C6HsN.C.(NtBu)- h C8. The activity towardsethylene polymerization has been investigated for ligand C8.