Aminopyridinate-Stabilized Lanthanoid Complexes: Synthesis, Structure and Polymerization of Ethylene and Isoprene

A series of aminopyridinate-stabilized dialkyl-lanthanoid complexes has been synthesized and characterized. The complexes were prepared by alkane elimination reacting [Ln(CH2SiMe3)(3)(thf)(2)] (Ln = Er, Yb, Lu) or [Ln(CH2Ph)(3)(thf)(3)] (Ln = Y, Er, Lu) with one equivalent of the bulky aminopyridine (2,6-diisopropylphenyl)-[6-(2,4,6-triisopropylphenyl)-pyridin-2-yl]amine. Single-crystal X-ray analyses were carried out for all of the benzyl derivatives. The reaction of these compounds with ammonium borate leads to the elimination of one of the two alkyl functions and affords organolanthanoid cations. The aminopyridinate-stabilized dialkyl-lanthanoid compounds can initiate the polymerization of isoprene after activation with perfluorinated tetraphenyl borates. The obtained polymers have a 3,4-content of 60-95%. The metal ion size as well as the addition of alkylaluminium compounds influences the microstructure of the obtained polymer. Aminopyridinate-stabilized organolanthanoid cations of Sc, Lu, Er and Y can polymerize ethylene in the presence of alkylaluminium compounds. The Lu, Er and Y complexes act as a CCTP catalyst and the erbium compound exhibits the highest activity.