Synthesis of rare-earth-metal-in-cryptand dications, [Ln(2.2.2-cryptand)]2+, from Sm2+, Eu2+, and Yb2+ silyl metallocenes (C5H4SiMe3)2Ln(THF)2.

Cp'2Ln(THF)2 metallocenes (Cp' = C5H4SiMe3) react with 2.2.2-cryptand (crypt) to form Ln2+-in-crypt complexes, [Ln(crypt)(THF)][Cp'3Ln]2 (Ln = Sm, Eu) and [Yb(crypt)][Cp'3Yb]2, that contain Ln2+ ions surrounded only by neutral ligands. A bimetallic, mixed-ligand metallocene/opened-crypt complex of Sm2+, [Sm(C16H32N2O6-κ2O:κ2O')SmCp''2], was obtained by KC8 reduction of Cp''2Sm(THF) [Cp'' = C5H3(SiMe3)2] in the presence of crypt.