Proton Affinity in the Chemistry of Beta-Octamolybdate: HPLC-ICP-AES, NMR and Structural Studies

The affinity of [β-Mo(8)O(26)](4−) toward different proton sources has been studied in various conditions. The proposed sites for proton coordination were highlighted with single crystal X-ray diffraction (SCXRD) analysis of (Bu(4)N)(3)[β-{Ag(py-NH(2))Mo(8)O(26)]}] (1) and from analysis of reported structures. Structural rearrangement of [β-Mo(8)O(26)](4−) as a direct response to protonation was studied in solution with (95)Mo NMR and HPLC-ICP-AES techniques. A new type of proton transfer reaction between (Bu(4)N)(4)[β-Mo(8)O(26)] and (Bu(4)N)(4)H(2)[V(10)O(28)] in DMSO results in both polyoxometalates transformation into [V(2)Mo(4)O(19)](4−), which was confirmed by the (95)Mo, (51)V NMR and HPLC-ICP-AES techniques. The same type of reaction with [H(4)SiW(12)O(40)] in DMSO leads to metal redistribution with formation of [W(2)Mo(4)O(19)](2−).