Zirconium complexes incorporating diaryldiamidoferrocene ligands: generation of cationic derivatives and polymerization activity towards ethylene and 1-hexene

Palladium-catalyzed coupling of ArX (ArX = MesBr, 2,6-dichloroiodobenzene and 9-bromonaphtalene) with 1,1'-diaminoferrocene afforded a series of substituted diamide ligands Fc(NHAr)(2) (1). A Zr-dibenzyl complex 2 of the mesityl-substituted ligand was synthesized using ZrBn4, and its ability to act as precatalyst for olefin polymerization was investigated. Abstraction of one benzyl group using B(C6F5)(3) resulted in the zwitterionic species [LZrBn][BnB(C6F5)(3)] (3), which reacted slowly (approximately 30 min) with ethylene to afford the monoinsertion product [LZrCH2CH2CH2Ph][BnB(C6F5)(3)]. Further insertions of ethylene were slower and led, after 2 h, to the di- and tri-insertion products. Use of [Ph3C][B(C6F5)(4)] as an activator resulted in a competent 1-hexene polymerization catalyst affording high molecular weight poly-l-hexene with a PDI of 1.3-1.4. (C) 2002 Elsevier Science B.V. All rights reserved.