New Bulky Allyl Complexes of Lanthanide Metals: Role of Alkali-Metal Cations in Controlling Solid-State and Solution Assemblies in Precatalysts

The reaction of the bulky allyl anion [1,3-C 3 H 3 (SiMe 3 ) 2 ] - with SmI 2 (THF) 2 gives the allyl-bridged dimer [Sm(C 3 H 3 (SiMe 3 ) 2 ) 3 {μ-K(THF) 2 }] 2, the first structurally authenticated Sm(II) allyl complex. The compound is a highly effective single-component catalyst for the polymerization of methyl methacrylate and ε-caprolactone.