Novel bimetallic LnIII/VIV (Ln = Gd, Tb, Dy, Er, Yb, Lu) compounds with cyclopropane-1,1-dicarboxylate anions and bulky tetrabutylammonium cations: synthesis, structure, magnetic properties, and thermal decomposition

Abstract

The reactions of oxovanadium(IV) sulfate with cyclopropane-1,1-dicarboxylic acid (H₂cpdc), Bu₄NOH, and lanthanide(III) nitrates in water solutions yielded a series of bimetallic ionic compounds (Bu₄N)[Ln(H₂O)₈][(VO)(cpdc)₂(H₂O)]₂·2/3H₂O (LnV₂, Ln = Gd, Tb, Dy, Er, Yb, Lu), whose crystal structures are constructed from supramolecular H-bonded layers separated by Bu₄N⁺ cations. Single-crystal X-ray diffraction (SC-XRD) was used to determine the crystal structures of GdV₂, TbV₂, and DyV₂, and their isostructurality with ErV₂, YbV₂, and LuV₂ was proved by powder X-ray diffraction (PXRD). According to alternating current (ac) magnetic susceptibility measurements, GdV₂, DyV₂, YbV₂, and LuV₂ exhibit field-induced slow relaxation of magnetization. The influence of the Ln³⁺ ion on ac magnetic behavior of compounds LnV₂ was explained using quantum chemical calculations. Thermal decomposition of GdV₂ in an Ar atmosphere was studied. The end product of the solid-phase thermolysis of GdV₂ in air at 600 °C was shown to be the complex oxide GdVO₄ with the admixture of V₂O₅.