Toluene solutions of Nb(toluene)(2) react with ethylenediamine solutions of K3E7 (E = As, Sb) in the presence of 2,2,2-crypt to give [NbAS(8)](3-) (2) and [NbSb8](3-) (3) ions, respectively, in low yields. The Cs-133 NMR spectroscopy, ESIMS results (negative ion mode), and single-crystal X-ray structures of the ions are reported. The complexes have S-8-like E-8 rings with Nb atoms in the center. The 1:1 complex of 2 with Cs was observed in solution and also in the gas phase as the oxidized ion [CsNbAS(8)](1-). The anion 2 selectively binds to Cs+ in solution even in the presence of excess Na+. Other gas-phase ions formed include [Cs-2(NbAS(8))](1-), [KCs(NbAS(8))](1-), [KCs(NbAS(8))(2)](1-), [KNbAs8](1-), and [K2NbAs8](1-).