Two new beta-octamolybdate supported rate earth metal complexes: [NH_4]_2{Gd(DMF)_7}_2(beta-Mo_8O_26)][beta-Mo_8O_26] and [NH_4][La(DMF)_7(beta-Mo_8O_26)]

摘要

Two novel beta-octamolybdate supported rate earth metal complexes, [NH_34]_2[{Gd(DMF)_7(beta-Mo_8O_26)}][beta-Mo_8O_26] 1 and [NH_4][La(DMF)_7(beta-Mo_8O_26)] 2, were obtained from the reaction of (NH_4)_6Mo_7O_24·4H_2O with LnCl_3 (Ln = Gd for 1 and La for 2) at low pH values in the mixed solvents of H_2O/DMF or H_2O/DMF/CH_3CN. The single X-ray diffraction studies reveal that 1 consists of discrete centrosymmetric heterometallic decanulear [{Gd(DMF)_7]_2-beta-Mo_8O_26]~(2+), [beta-Mo_8O_26]~(4-) and two amino cations. In each decanular [{Gd(DMF)_7}_2-beta-Mo_8O_26]~(2+) cation, the beta-octamolybdate moiety is linked to two eight-coordinated Gd~(III) cations, which is coordinated by seven DMF ligands and one terminal oxygen atom of molybdenum center. Compound 2 is built up from DMF coordinated La~(III) fragment and beta-octamolybdate unit jointed 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 beta-[Mo_8O_26]~(4-) ligand or the presence of zero-field splitting.