Perfluorofluorenyl anions and their use as co-catalysts in the zirconocene-promoted polymerization of olefins

Fluorofluorenes [1,2,3,4,5,6,7,8-octafluoro-9-(pentafluorophenyl)-9H-fluorene (OFPF), 1,2,3,4,5,6,7,8-octafluoro-9-(2,4-trifluoromethylphenyl)-9H–fluorene (OFTF), and 1,2,3,4,5,6,7,8-octafluorofluorene (OFF)] react with sodium hydride or with lithium alkyls to give fluorofluorenyl anions which have been characterized in solution by 19F NMR spectroscopy. OFPF is deprotonated by ethylenediamine, by HMPT and by 1,7-diazo-bicyclo(5,4)-undec-7-ene (DBU), as shown by 1H and 19F NMR spectrometry. The new compound [rac-ethylene-bis(η5-4,5,6,7-tetrahydroindenyl)]diallylzirconium(IV) (ZRAL), as prepared from [rac-ethylene-bis(η5-4,5,6,7-tetrahydroindenyl)]dichloridezirconium(IV) and allylmagnesium chloride, undergoes allyl abstraction with OFPF, CPh3[B(C6F5)4], and B(C6F5)3 forming zirconium-containing cations, as established by 1H and 19F NMR spectrometry. Toluene/pentafluoroanisole solutions of the fluorinated anions, in combination with ZRAL, catalyze the polymerization of ethylene, with an activity comparable to that of MAO or CPh3[B(C6F5)4], a remarkable increase of activity being observed with the ZRAL/OFPF system.