Living Coordinative Chain-Transfer Polymerization and Copolymerization of Ethene, α-Olefins, and α,ω-Nonconjugated Dienes using Dialkylzinc as “Surrogate” Chain-Growth Sites

Highly efficient, rapid, and reversible chain transfer between active transition-metal-based propagating centers derived from {Cp*Hf(Me)[N(Et)C(Me)N(Et)]}[B(C 6 F 5 ) 4 ] (Cp* = η 5 -C 5 Me 5 ) ( 1a ) or {Cp*Hf(Me)[N(Et)C(Me)N(Et)]}[B(C 6 F 5 ) 3 Me] ( 1b ) and multiple equivalents of dialkylzinc (ZnR 2 ) acting as “surrogate” chain-growth sites has been achieved for establishing the living coordinative chain-transfer polymerization (CCTP) of ethene, α-olefins, and α,ω-nonconjugated dienes and living CCTP copolymerization of ethene with α-olefins and α,ω-nonconjugated dienes. These living CCTP processes not only provide a work-around solution to the “one chain per metal” cap on product yield currently limiting traditional living coordination polymerization of ethene and α-olefins but, in addition, provide access to practical volumes of a variety of unique new classes of precision polyolefins of tunable molecular weights and very narrow polydispersity ( M w / M n ≤ 1.1).