Hydrothermal routes to new sodium hydrogen polytungstates†
Abstract
The new acidic sodium polytungstates, Na5[H7W12O42]·20H2O (1) and Na2[H10W12O42]·20H2O (2), have been synthesised under hydrothermal conditions where variations of pH and temperature allow control of the protonation of the [W12O42]12−cluster in the products. The polytungstate cluster, [HnW12O42](12−n)−, in each compound consists of the well known polyhedral unit based on 12 edge- and corner-sharing WO6 octahedra, though the decoration of this unit with varying levels of