Reaction pathway for the formation of binuclear samarocene hydride from monomeric alkyl samarocene derivative and the effective catalysis of samarocene hydride for the block copolymerization of ethylene with polar monomers

The X-ray analysis of Me2Si(C5H3-3-Me3Si)(2)SmCH(Me3Si)(2)(THF) (1) revealed a monomeric structure, while the hydrogenated complex, [Me2Si(C5H3-3-Me3Si)(2)SmH(THF)](2), (2), exhibits binuclear mu-H structure to indicate that Me2SiCp'M-2 --> M(mu-Me2SiCp'(2))(2)M rearrangement of the eta(5)-eta(5) ligation occurs during the hydrogenation. The resulting samarocene hydride 2 exhibits high activity as an initiator for the bloch copolymerization of ethylene with polar monomers such as methyl methacrylate and epsilon-caprolactone.