Synthesis and novel polymerization and copolymerization reactions of new organolanthanide complexes

Reactions of (C5Me5)(2)Sm(THF)(2) with the potassium salts of monodentate anionic ligands ER (ER=OAr, SAr, (NRR2)-R-1, etc.) yielded a series of C5Me5/ER-ligated samarium(II) complexes, which were stabilized by the neutral "C5Me5K" ligand. These complexes act as a unique catalytic system which can not only polymerize styrene and ethylene, but also copolymerize them into block styrene-ethylene copolymers under the presence of both monomers. Addition of an appropriate cocatalyst such as MMAO or AlR3/[Ph3C][B(C6F5)(4)] to the samarocene complex (C5Me5)(2)Sm(THF)(2) or (C5Me5)(2)Sm (mu -Me)(2)AlMe2 afforded a novel catalytic system for stereospecific 1,4-cis living polymerization of butadiene and copolymerization of butadiene with styrene. The samarium(II) bis(aryloxide) complex Sm(OAr)(2)(THF)(3) showed an extremely high activity for ring-opening polymerization of epsilon -caprolactone and delta -valerolactone and copolymerization of epsilon -caprolactone with gamma -butyrolactone.