Structural studies of decavanadate compounds with organic molecules and inorganic ions in their crystal packing

The formation of decavanadates containing amine counter-ions is explored to get a better insight into the resulting crystal packing. From mixtures containing the Schiff base H₂(SO₃-sal)₂en and vanadate, two different compounds containing decavanadate units have been characterised by X-ray diffraction. The structure of 1 consists of [V₁₀O₂₈]⁶⁻ monomers united by K⁺, ethylenediamine cations and H₂O molecules, which act as bridging atoms between the layers, forming a three-dimensional array. The structure of 2 contains vanadium triprotonated decavanadate anions, [H₃V₁₀O₂₈]³⁻, in one-dimensional vertical chains, bonded by interdecavanadate hydrogen bonds. The interchain region is populated by (H₂en)²⁺ cations and H₂O molecules, which form a network of hydrogen bonds. From the filtrate solution of the reaction mixture containing V^IVOSO₄, d,l-diaminopropionic acid and salicylaldehyde, which also contained triethylamine, a diprotonated decavanadate 3 was obtained. Compound 3 consists of decavanadate vertical dimers, surrounded by triethylamonium cations that preclude the interaction between the dimers. Bond valence calculations were used to confirm the degree of protonation of the decavanadate anions.