Cationic Metallocene Polymerization Catalysts Based on Tetrakis(pentafluorophenyl)borate and Its Derivatives. Probing the Limits of Anion “Noncoordination” via a Synthetic, Solution Dynamic, Structural, and Catalytic Olefin Polymerization Study

Abstract

The synthesis and properties of two soluble, weakly coordinating derivatives of the tetrakis(perfluoroaryl)borate anion B(4-C6F4TBS)4- and B(4-C6F4TIPS)4- (TBS = tert-butyldimethylsilyl and TIPS = triisopropylsilyl) are reported. Reaction of the trityl salts of the above anions with a variety of zirconium and thorium L2MMe2 complexes in benzene or toluene affords the cationic ion-paired methyl complexes L2MMe+X- or the corresponding hydrido complexes L2MH+X- (L2 = bis(cyclopentadienyl)- or cyclopentadienylamido-type ligand) when the reaction is carried out under dihydrogen. The solid state structure of the complex (Me5Cp)2ThMe+B(C6F5)4- has been characterized by X-ray diffraction. The B(C6F5)4--based zirconocenium methyl complexes L2MMe+ are unstable at room temperature with respect to, among other factors, intramolecular C−H activation of the ligand framework. In general, the thermal stabilities of the B(C6F4TBS)4-- and B(C6F4TIPS)4--derived complexes are greater than those of the corresponding B(C6F5)4-...