News from an Old Ligand: The Triple‐Decker Ion Triple, Tris([18]Crown‐6)‐disodium Bis(tetraphenycyclopentadienide)

Abstract

Three [18]crown-6 ligands and two sodium ions surprisingly form a triple-decker sandwich dication, pictured schematically on the right. Due to sixfold O-coordination of each sodium ion to the outer crown ethers, but only two Na+ ċ O contacts each to the central ligand, the outer macrocyclic rings are distorted to a hemispherical conformation, whereas the central ring adopts a rectangular shape.