Ordnung muss sein: heteroelement order and disorder in polyoxovanadates

Abstract

The first mixed antimonato–germanato polyoxovanadates were synthesized using two different strategies, highlighting the critical role of the precursors. Following the traditional route using multiple single sources as precursors the polyanions [V₁₅Sb₂Ge₄O₄₂(OH)₄(H₂O)]⁶⁻ (1) and [V₁₅Sb₃Ge₃O₄₂(OH)₃(H₂O)]⁶⁻ (2) are obtained, which display disorder of their Sb/Ge positions, indicating that clusters of different compositions are in equilibrium in solution. In contrast, if the water-soluble single-source precursor {Ni(en)₃}₃[V₁₅Sb₆O₄₂(H₂O)]·ca. 15H₂O is reacted with GeO₂, {Ni(en)₃}₃[V₁₅Sb₃Ge₃O₄₂(OH)₃(H₂O)]·≈9H₂O (3) forms, in which Sb and Ge occupy distinct positions that might have been formed via partial substitution reactions in the {V₁₅Sb₆} precursor.