Four new complexes MaHb[X(NbO2)W11O39] . nH(2)O(M=Me4N+, Bu4N+; X= Ga,
Ge) were synthesized and characterized by elementary analysis, IR, UV
-Vis, W-183 NMR and electrochemical method. W-183 NMR spectra of the c
omplexes consist of six peaks, as expected for monosubstituted Keggin-
type.