The Mechanism of Polymerization of Butadiene by “Ligand-Free” Nickel(II) Complexes

Polymerization of 1,3‐dienes and styrene catalyzed by cationic allyl Ni(II) complexes

“…Late transition metal complexes of nickel have been employed as single component catalysts in 1,3‐diene polymerization. Both neutral and cationic (allyl)Ni(II) catalysts with a variety of ligands have been examined 8, 21–31. Neutral complexes based on [(allyl)NiX] 2 dimers [Scheme (A)] are active 1,3‐diene polymerization catalysts and the identity of X influences the reactivity and selectivity in BD polymerization.…”

Application of Ultrahigh‐Field 59Co Solid‐State NMR Spectroscopy in the Investigation of the 1,2‐Polybutadiene Catalyst [Co(C8H13)(C4H6)]

“…[7] In sharp contrast to the sPBD systems, the formation of 1,4-polybutadiene has been fully explored by Taube and Tobisch, [8] and recent work has experimentally confirmed the mechanism. [9] Thus, the application of spectroscopic tools to 1 will greatly aid in our understanding of this and other catalysts. Solution-state NMR studies would provide the best insights into the mechanism of the homogeneous catalyst 1; however, information garnered from solid-state studies may also provide crucial insights into the activity of this unique system.…”

Synthesis, characterization, and reactivity of (π-allyl)palladium(II) wrap-around complexes with 1,3-dienes

“…Taube has shown that ''ligand-free'' wraparound Ni(II) complexes are highly reactive initiators for butadiene (BD) polymerization [4]. We have previously spectroscopically observed (allyl)Ni (g 4 -butadiene) + , 4, at low temperatures and showed that this species reacts rapidly with two equivalents of BD to generate a third insertion, wrap-around complex 5 shown in Scheme 2 [5]. At higher temperatures, the third insertion product initiates polymerization of BD and intermediates in the chain growth have been identified [5,6].…”