Coupling Reactions of Functionalized Zintl Ions [E₉Cd(C₆H₅)]³⁻ (E = Sn, Pb) with Tributyltinhydride: Synthesis and Isolation of {Sn₉CdSn[(CH₂)₃CH₃]₃}³⁻

Reaction of ethylenediamine solutions of K₄E₉ (E = Sn, Pb) with diphenylcadmium yielded the Cd(C₆H₅)-functionalized Zintl ions, closo-[E₉Cd(C₆H₅)]³⁻ (E = Sn (1); Pb (2)). Solution reactivity studies of 1 with tributyltinhydride in pyridine revealed that the cluster is capable of undergoing a coupling reaction to yield the tributyltin-functionalized cluster, closo-{Sn₉CdSn[(CH₂)₃CH₃]₃}³⁻ (3). In-situ monitoring of this reaction by ¹H and ¹³C{¹H} NMR spectroscopy reveals the formation of the tributyltin functionalized cluster anion in addition to free benzene. Species 1−3 were characterized in the solid-state as [K(2,2,2-crypt)]⁺ salts by single crystal X-ray diffraction and elemental analysis, while the presence of all three cluster anions in solution was confirmed by ¹H and ¹³C{¹H} NMR spectroscopy and electrospray mass-spectrometry.