Probing the Catalytically Active Species in POM‐Catalysed DNA‐Model Hydrolysis**

Phosphoester hydrolysis is an important chemical step in DNA repair. One archetypal molecular model of phosphoesters is para-nitrophenylphosphate (pNPP). It has been shown previously that the presence of molecular metal oxide [Mo7O24]6− may catalyse the hydrolysis of pNPP through the partial decomposition of polyoxomolybdate framework resulting in a [(PO4)2Mo5O15]6− product. Real-time monitoring of the catalytic system using electrospray ionisation mass spectrometry (ESI-MS) provided a glance into the species present in the reaction mixture and identification of potential catalytic candidates. Following up on the obtained spectrometric data, Density Functional Theory (DFT) calculations were carried out to characterise the hypothetical intermediate [Mo5O15(pNPP)2(H2O)6]6− that would be required to form under the hypothesised transformation. Surprisingly, our results point to the dimeric [Mo2O8]4− anion resulting from the decomposition of [Mo7O24]6− as the active catalytic species involved in the hydrolysis of pNPP rather than the originally assumed {Mo5O15} species. A similar study was carried out involving the same species but substituting Mo by W. The mechanism involving W species showed a higher barrier and less stable products in agreement with the non-catalytic effect found in experimental results

Chromate-mediated one-step quantitative transformation of PW 12 into P 2W 20 polyoxometalates

The addition of H 3PW 12O 40 to an aqueous solution of K 2CrO 4 led to the hydrolysis of [PW 12O 40] 3- with its quantitative conversion into K 13[KP 2W 20O 72]. K 13[KP 2W 20O 72] in these chromate-containing solutions was characterized by 183W and 31P NMR, EXAFS, SAXS, and EPR spectroscopy. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim