High-pressure 17O NMR studies on some aqueous polyoxoions in water

Reactive properties of nanometer-size aqueous clusters and water-exchange mechanism for these clusters have been examined by using 17O NMR method. Merbach and co-workers conducted high-pressure 17O NMR experiments on the V(H2O)2+6 ion and reported activation volume values. High-pressure 17O NMR measurements were also conducted on the pentaquaoxovanadium ion [VO(H2O)5]2+ and activation volume was found to be small and positive. Water-exchange mechanism generally become more dissociative as the charge of the metal increases, but here, although the oxidation number of the vanadium changes from +2 to +4, the activation volume decreases. Richens and co-workers examined the [Mo3O4(H2O)9[4+ trinuclear complex, which has four types of structural oxygens, all of which can be detected by 17O NMR spectroscopy.