Synthesis, structural characterization, and properties of two new polyoxovanadates based on decavanadate [V10O28]6−

Two new decavanadate metal compounds, [Co(pyim)3]2[V10O28]·7H2O (1) and [Ni(pyim)3]2[H2V10O28]·4H2O (2) (pyim = 2-(2-pyridyl)-imidazole), have been synthesized under hydrothermal conditions and characterized by elemental analysis, single-crystal X-ray diffraction analysis, infrared spectra, powder X-ray diffraction analysis, and thermogravimetric analysis. Crystallographic analysis reveals that 1 is constructed from [V10O28]6−, metal cation [Co(pyim)3]3+, and water. [V10O28]6− clusters are connected by waters through O–H⋯O hydrogen bonds to form a sheet structure which is further connected by N–H⋯O hydrogen bonds to form a 3-D supermolecular framework. In 2, although [Ni(pyim)3]2+ is similar to [Co(pyim)3]3+ in 1, the M−O cluster anion is protonated [H2V10O28]4−.