The oxo-nitrosyl compound (n-Bu4N)(2)[{Na(MeOH)}Mo5O13(OMe)(4)(NO)]. 3MeOH reacts with various nickel(II) salts in methanol to give (n-Bu4N)(2)[{Ni(MeOH)(2)}(2){Mo(NO)}(2)(mu(3)-OH)(2)(mu-OMe)(4){Mo5O13(OMe4(NO)}(2)] which has been characterized by single-crystal X-ray diffraction analysis and magnetic susceptibility measurements. This reaction shows the dual behavior of the defect Lindqvist-type species [Mo5O13(OMe)(4)(NO)](3-), which can act both as a ligand and as a source of the {Mo(NO)}(3+) unit. Furthermore, the reaction is reminiscent of the dissolution-precipitation of oxide supports in the preparation of supported catalysts and provides a novel illustration of the potential of polyoxometalates for probing the reactivity of oxides. The new polyoxomolybdate is made of a central rhomb-like (Ni2Mo2) cluster linked to two terminal [Mo5O13(OMe)(4)(NO)](3-) units, each terminal cluster being linked to a molybdenum center of the central unit through two oxo ligands. The two Ni(II) ions are coupled in a ferromagnetic way (J = 13.1 cm(-1)).