Gas Phase, Solution, and Solid State Alkali Ion Binding by the [NbE₈]^3- (E = As, Sb) Complexes: Synthesis, Structure, and Spectroscopy

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 [NbAs8]3- (2) and [NbSb8]3- (3) ions, respectively, in low yields. The 133Cs NMR spectroscopy, ESIMS results (negative ion mode), and single-crystal X-ray structures of the ions are reported. The complexes have S8-like E8 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 [CsNbAs8]1-. The anion 2 selectively binds to Cs+ in solution even in the presence of excess Na+. Other gas-phase ions formed include [Cs2(NbAs8)]1-, [KCs(NbAs8)]1-, [KCs(NbAs8)2]1-, [KNbAs8]1-, and [K2NbAs8]1-.