Decavanadate with a novel coordination complex: Synthesis and characterization of (NH4)2[Ni(H2O)5(NH3)]2(V10O28)·4H2O

A new compound (NH4)2[Ni(H2O)5(NH3)]2[V10O28]·4H2O (1) containing a {V10O28} 6− anionic cluster and a novel complex cation, [Ni(H2O)5(NH3)]2 +, has been synthesized and fully characterized by single crystal X-ray crystallography, spectroscopy and thermogravimetric analysis. The presence of the ammonia ligand in the complex cation in 1 was established unambiguously by X-ray crystallography and variable temperature (200–400 °C) thermogravimetric analyses in combination with FTIR spectroscopic studies. The formation of the novel complex species {Ni(H2O)5(NH3)}2 + during the synthesis of 1 can be rationalized in terms of ligand substitution involving {Ni(H2O)6}2 +.