LAUSR

Abstract Three new heteronuclear [FeW9O34]-based sandwich-type complexes [FeIII2MnII2(H2O)2(FeW9O34)2]12− (1), [FeIII2MnIII2(H2O)2(FeW9O34)2]10− (2) and [FeIII2NiII2(H2O)2(FeW9O34)2]12− (3) have been synthesized by an innovative method of pH-controllable degradation in aqueous solution, in which the [FeW12O40]5− precursor could be predominantly degraded into the trivacant [FeW9O34]11− anion. The active ligand of trivacant [FeW9O34]11− anion can catch in situ the mixed transition metal ions to conduce a directed coordination assembly reaction. These three heteronuclear complexes have been characterized by elemental analysis, single-crystal and powder X-ray diffraction analyses, IR spectra, UV–vis spectra, and thermal gravimetric analysis, cyclic voltammetry, magnetic properties, and thermal gravimetric analysis. Complexes 1 and 3 exhibit obvious catalytic activities for electrocatalytic reduction of nitrate. Compared with 1, the magnetic property of 2 shows a remarkable change by only a conversion of Mn(II) into Mn(III), so that a strong ferromagnetic interaction occurs in 2.