The Heaviest Alkali Metallocene: Structure of an Anionic Cesocene Triple-Decker

摘要

We recently reported the synthesis and structure of the simplest metallocene sandwich complex, the lithocene anion, which was obtained by reacting two equivalents of CpLi with PPh_4CI in THF [Eq. (a)]. The approximate D_(5d) staggered lithocene sandwich is remarkably similar to the isovalent. diagonally related, alkaline earth analogue Cp_2Mg. At the same time Paquette et al. published the structure of a substituted lithocene anion in which the noncoordinating cation is a bis([ 12]crown-41 solvated Li cation [Eq. (b)]. Since this new class of anionic alkali metallocenes is particularly interesting from a theoretical point of view, we have now focused our attention on the heavier alkali metal analogues.