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 tributyltin hyd ride in pyridine revealed that the cluster is capable of undergoing a coupling reaction to yield the tributyltin-functionalized cluster, closo-{Sn9CdSn[(CH2)(3)CH3](3)}(3-) (3). In-situ monitoring of this reaction by H-1 and C-13{H-1} 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 H-1 and C-13{H-1} NMR spectroscopy and electrospray mass-spectrometry.