Assembly of trimeric polyoxovanadate aggregates based on [MnV13O38]7- building blocks and lanthanide cations

Three trimeric polyoxovanadate based on 1:13 anions [MnV13O38](7-) with lanthanide cations Ln(3+) (Ln = La, Ce and Nd) and pyridine-3-carboxylic acid: HK3{[Ln(H2O)4]6[MnV13O38]3(SO4)2}·3(C6H6NO2)·nH2O (Ln = La 1, Nd 3; n = 33 for 1, 20 for 3), H(2.5)K(1.5){[Ce(H2O)4]6[MnV13O38]3(SO4)2}·3(C6H6NO2)·20.5H2O (2) (C6H5NO2 = pyridine-3-carboxylic acid) have been synthesized and characterized by elemental analysis, IR spectroscopy, UV spectroscopy, TG analysis, XPRD, electrochemical analyses, magnetism and single-crystal X-ray diffraction. Compounds 1-3 are isostructural and crystallized in the hexagonal system, space group P6(3)/m. Compounds 1-3 contain an unusual trimeric polyoxoanion [{Ln2MnV13O38}3(SO4)2](7-), representing the first polyoxovanadate-based trimeric aggregate with rare earth ions. The electrochemical and electrocatalytic properties of the compounds have been investigated. Magnetic studies indicate that antiferromagnetic interactions exist in the compounds.