Endohedral anionic nine-atom Zintl clusters of the elements tin and lead with lithium counterions

Intermetalloid clusters are considered as highly charged soluble models for intermetallic phases. While their bonding situation is not fully understood, their solubility makes them promising candidates for the fabrication of nanostructured intermetallic materials. We report the synthesis of endohedral [TM@Tt₉]^4- (Tt = Sn and TM = Fe, Co, Ni, Pd; Tt = Pb and TM = Pd, Pt) clusters from solutions of K₄Sn₉ and the appropriate transition metal complex. The potassium ions are replaced with lithium cations through a simple salt metathesis reaction using LiCl. The intermetalloid cluster compounds adopt crystal structures, which are - except for the presence of the TM at the cluster center - isotypic either to the related Li/Sn₉/en or Li/Pb₉/en compounds containing unfilled clusters. The new compounds are further investigated by Raman, NMR, and EPR spectroscopy.