The influence of three exogenous ligands (acetate, formate and carbonate) on the condensation process of the [Mo2O4]2+ dioxocation with the [O3PCH2PO3](4-) group has been investigated. Four cyclic or bicyclic compounds have been isolated and characterized by X-ray diffraction studies. Two closely related acetato and formato ovoidal duodecanuclear compounds, Na24[Na4(H2O)6[(Mo2O4)10(O3PCH2PO3)10(CH3COO)8(H2O)4]].103H2O (1) and Na28[Na2[(Mo2O4)10(O3PCH2PO3)10(HCOO)10]].110H2O (2), respectively, have been obtained. Their structures can be described as two interconnected nonequivalent wheels, delimiting a large cavity. When the condensation is performed in similar conditions but replacing carboxylato groups by carbonato ligands, the ellipsoidal octanuclear Na11[Na(H2O)2[(Mo2O4)4(O3PCH2PO3)4(CO3)2]].70H2O (3) compound is isolated. 31P NMR spectroscopic studies have shown that complexes 1 and 3 are stable in solution at room temperature. Nevertheless, on heating an aqueous solution of 3, the Na8[(Mo2O4)3(O3PCH2PO3)3(MoO4)].18H2O (4) complex, free of carbonato groups, is obtained. 4 is a hexanuclear Mo(V) wheel encapsulating a tetrahedral [Mo(VI)O4](2-) anion. Its rational synthesis using a controlled Mo(V)/Mo(VI) ratio is also presented.