Fernández, Jorge A. López, Xavier Bo, Carles Graaf, Coen de Baerends, Evert J. Poblet, Josep M. Polyoxometalates with Internal Cavities:  Redox Activity, Basicity, and Cation Encapsulation in [X<i><sup>n</sup></i><sup>+</sup>P<sub>5</sub>W<sub>30</sub>O<sub>110</sub>]<sup>(15-</sup><i><sup>n</sup></i><sup>)-</sup> Preyssler Complexes, with X = Na<sup>+</sup>, Ca<sup>2+</sup>, Y<sup>3+</sup>, La<sup>3+</sup>, Ce<sup>3+</sup>, and Th<sup>4+</sup> The Preyssler anion, of general formula [X<i><sup>n</sup></i><sup>+</sup>P<sub>5</sub>W<sub>30</sub>O<sub>110</sub>]<sup>(15-</sup><i><sup>n</sup></i><sup>)-</sup>, is the smallest polyoxometalate (POM) with an internal cavity allowing cation exchange with the solution. The Preyssler anion features a rich chemistry evidenced by its ability to accept electrons at low potentials, to selectively capture various metal cations, and to undergo acid−base reactions. A deep understanding of these topics is herein provided by means of DFT calculations on the title series of compounds. We evaluate the energetics of the release/encapsulation process for several X<i><sup>n</sup></i><sup>+</sup> cations and identify the effect of the encapsulated ion on the properties of the Preyssler anion. We revisit the relationship between the internal cation charge and the electrochemical behavior of the POM. A linear dependence between the first one-electron reduction energies and the encapsulated X<i><sup>n</sup></i><sup>+</sup> charge is found, with a slope of 48 mV per unit charge. The protonation also shifts the reduction potential to more positive values, but the effect is much larger. In connection to this, the last proton's p<i>K</i><sub>a</sub> = 2 for the Na<sup>+</sup> derivative was estimated to be in reasonable agreement with experiment. The electronic structure of lanthanide derivatives is more complex than conventional POM structures. The reduction energy for the Ce<sup>IV</sup>-Preyssler + 1e<sup>-</sup> → Ce<sup>III</sup>-Preyssler process was computed to be more exothermic than that of very oxidant species such as S<sub>2</sub>Mo<sub>18</sub>O<sub>62</sub><sup>4-</sup>. 48 mV;cation charge;encapsulated Xn;cation exchange;metal cations;Preyssler anion features;Preyssler anion;1 e;Na;POM structures;title series;oxidant species;lanthanide derivatives;electrochemical behavior;Cation Encapsulation;reduction energy;encapsulated ion;unit charge;DFT calculations 2007-10-10
    https://acs.figshare.com/articles/journal_contribution/Polyoxometalates_with_Internal_Cavities_Redox_Activity_Basicity_and_Cation_Encapsulation_in_X_i_sup_n_sup_i_sup_sup_P_sub_5_sub_W_sub_30_sub_O_sub_110_sub_sup_15_sup_i_sup_n_sup_i_sup_sup_Preyssler_Complexes_with_X_Na_sup_sup_Ca_sup_2_sup_Y_sup_3_sup_La_s/2981830
10.1021/ja0737321.s001