Divalent Lanthanide Tetraisobutylaluminates: Reactivity and Living Isoprene Polymerization
Eric C. Moinet, Benjamin M. Wolf, Olivier Tardif, Cäcilia Maichle‐Mößmer, Reiner Anwander
Abstract
Abstract Lanthanide (Ln) tetraisobutylaluminates constitute key components in commercial 1,3‐diene polymerization catalysts, and likewise are the homogeneous rare‐earth‐metal catalysts of prime industrial importance. Discrete divalent rare‐earth‐metal complexes [Ln(Al i Bu 4 ) 2 ] (Ln=Sm, Eu, Yb) reported here display the first structurally characterized homoleptic metal tetraisobutylaluminates. Treatment of [Ln(Al i Bu 4 ) 2 ] with C 2 Cl 6 gives access to Sm II /Sm III mixed‐valence cluster [Sm 6 Cl 8 (Al i Bu 4 ) 6 ] and the Yb II cluster [Yb 4 Cl 4 (Al i Bu 4 ) 4 ], respectively. Reaction with B(C 6 F 5 ) 3 leads to hydride abstraction and formation of arene‐coordinated hydroborates such as [Sm{HB(C 6 F 5 ) 3 } 2 (toluene) 2 ]. Complexes [Ln(Al i Bu 4 ) 2 ] engage in single‐component isoprene polymerization, affording high cis ‐1,4 polyisoprenes with narrow molecular weight distributions. Binary [Yb(Al i Bu 4 ) 2 ]/[HNPhMe 2 ][B(C 6 F 5 ) 4 ] fabricates polyisoprene in a perfectly living manner. The catalytically active species are scrutinized by NMR spectroscopy.