Two new β-octamolybdate supported rare earth metal complexes: [NH4]2[{Gd(DMF)7}2(β-Mo8O26)][β-Mo8O26] and [NH4][La(DMF)7(β-Mo8O26)]

Two novel β-octamolybdate supported rare earth metal complexes, [NH4]2[{Gd(DMF)7(β-Mo8O26)}][β-Mo8O26] 1 and [NH4][La(DMF)7(β-Mo8O26)] 2, were obtained from the reaction of (NH4)6Mo7O24·4H2O with LnCl3 (Ln=Gd for 1 and La for 2) at low pH values in the mixed solvents of H2O/DMF or H2O/DMF/CH3CN. The single X-ray diffraction studies reveal that 1 consists of discrete centrosymmetric heterometallic decanuclear [{Gd(DMF)7}2-β-Mo8O26]2+, [β-Mo8O26]4− and two amino cations. In each decanuclear [{Gd(DMF)7}2-β-Mo8O26]2+ cation, the β-octamolybdate moiety is linked to two eight-coordinated GdIII cations, which is coordinated by seven DMF ligands and one terminal oxygen atom of molybdenum center. Compound 2 is built up from DMF coordinated LaIII fragment and β-octamolybdate unit joined together through two terminal oxygen atoms of two molybdenum atoms. Ferromagnetic behavior is observed for 1 from the magnetic measurement, which might result from the exchange interaction through the bridging β-[Mo8O26]4− ligand or the presence of zero-field splitting.