Stereoselective polymerization of butadiene by a new dicationic nickel complex

The new dicationic nickel complex [dppfNi(MeCN)(4)[BF4](2) (dppf = 1,1'-bis(diphenylphosphino)ferrocene) in the presence of diethylaluminium chloride (AlEt(2)Cl) exhibited high activity on the 1,3-butadiene polymerization. Reaction time, temperature and aluminium/nickel molar ratio were optimized in order to achieve maximum activity and selectivity. Conversions higher than 90% were obtained in contrast to other nickel-based systems using phosphine ligands, the resulting polybutadiene showed high cis-1,4 (>80%) content and only small amount of 1,2-units (2%). All polymers presented low molecular weights (M(w) < 11800).239334