Insights into substitution effects and reactivity of Lindqvist-type polyoxometalates from DFT calculations

In this work, the geometric and electronic parameters of pure and vanadium-substituted anions of Lindqvist polyoxometalates have been investigated using DFT calculations. Active sites of all anions are identified through results on local and global reactivity descriptors. The results indicate that bridging oxygen atoms in all clusters are the most active sites. Using this, the mechanism of the catalytic generation of the hydroxyl radical from water was studied for the di-substituted Lindqvist polyoxometalate [V₂Mo₄O₁₉]⁴⁻. This study provides a detailed understanding of this important intermediate step in photo-oxidation reactions. The mechanistic route makes it possible to locate transition states and intermediates structures and demonstrates that the pre-association of the water molecule leads to an H abstraction with an energy barrier of 26.42 kcal/mol and OH radical and [HV₂Mo₄O₁₉]⁴⁻ as products in this step.