Isotopic oxygen exchange rates between [V18O42]12− and water

Summary From kinetic studies of¹⁸O-exchange between aqueous solutions of K₁₂V₁₈O₄₂ · 16H₂O and water it is concluded that [V₁₈O₄₂]^12– exists as a discrete ion in this medium. The rate of exchange is relatively slow (t_1/2ca. 6×10⁴s at 0°C) and obeys the McKay equation within the precision obtainable. The sensitivity of the ion to its environment in the solid state, leading to induced exchange, prevented a decision as to whether all oxygens are kinetically equivalent. It is clear, however, that the ions remains intact for long periods in solution in the absence of air.