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

## TL;DR

Researchers developed a method to create new cluster anions filled with transition metals and paired with lithium ions, offering insights into nanostructured materials.

## Contribution

A new synthetic protocol for creating endohedral intermetalloid clusters with transition metals and lithium counterions is introduced.

## Key findings

- Endohedral [TM@Tt9]4− clusters with TM atoms at the center were synthesized using K4Sn9 and transition metal complexes.
- Lithium cations replaced potassium ions via salt metathesis, forming stable intermetalloid cluster compounds.
- Crystal structures of the new compounds were found to be isotypic to known Li/Sn9/en and Li/Pb9/en compounds.

## Abstract

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.

A synthetic protocol for generating a series of polyhedral cluster anions that are endohedrally filled with transition-metal atoms and paired with lithium counterions is reported.