Reactions of exo ‐Substituted RSn 9 3− Clusters with Pd: Endohedral Cluster Formation and Oxidative Insertion

Pyridine/ethylenediamine solutions of [Sn 9 SnCy 3 ] 3− ( 1 ) react with [Pd(PPh 3 ) 4 ] to give new clusters [Pd@Sn 9 SnCy 3 ] 3− ( 2 ) and [Pd@Sn 9 PdSnCy 3 ] 3− ( 3 ), depending on stoichiometry. These compounds are formed sequentially and are the first transition metal derivates of exo ‐substituted Zintl clusters. Oxidative insertion of a Pd atom into the Pd@Sn 9 SnCy 3 bond of 2 to form 3 represents a new reaction type for Zintl cluster compounds. The conversion Sn 9 4− → 1 → 2 → 3 is a rare case in which charge and mass are conserved in a series of Zintl clusters. Complexes 1 , 2 , and 3 are all highly fluxional in solution. In all three clusters, the nine Sn vertices are in rapid exchange on the NMR timescale. In 1 and 2 , the exo ‐SnCy 3 substituent also scrambles intramolecularly around the outside of the clusters. In 3 , the SnCy 3 group remains attached to the vertex Pd atom. The disparate reactions with the other RSn 9 3− ions are discussed.