Reactions of exo-Substituted RSn93− Clusters with Pd: Endohedral Cluster Formation and Oxidative Insertion



Pyridine/ethylenediamine solutions of [Sn9SnCy3]3− (1) react with [Pd(PPh3)4] to give new clusters [Pd@Sn9SnCy3]3− (2) and [Pd@Sn9PdSnCy3]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@Sn9[BOND]SnCy3 bond of 2 to form 3 represents a new reaction type for Zintl cluster compounds. The conversion Sn94−123 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-SnCy3 substituent also scrambles intramolecularly around the outside of the clusters. In 3, the SnCy3 group remains attached to the vertex Pd atom. The disparate reactions with the other RSn93− ions are discussed.