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- .