Transient intermediates in the polymerisation of tungstate

Abstract

The reaction of alkaline solutions of Na₂[WO₄](ca. 10^–3 mol dm^–3) with acid has been studied by stopped-flow-spectrophotometric and indicator-spectrophotometric techniques. The formation of ‘acid paratungstate’, [H₈W₆O₂₄]^4–, has been detected. It is the most important of the transient intermediates formed ca. 500 ms after mixing, before decomposition to a mixture of [HW₆O₂₁]^5– and [(HW₆O₂₀)_n]^3n–. It is confirmed that this ‘acid paratungstate’ exists for some hours in tetramethylammonium chloride solution.