Activation mechanism of hydrogen peroxide by a divanadium-substituted polyoxometalate [gamma- PV2W10O38(mu-OH)(2)](3-): A computational study

作者：Liu, Chun-Guang^*; Chu, Yun-Jie

来源：Journal of Molecular Graphics and Modelling, 2018, 85: 56-67.

DOI：10.1016/j.jmgm.2018.07.009

• EFFECTIVE CORE POTENTIALS
• C-H OXIDATION
• MOLECULAR CALCULATIONS
• PHOSPHOTUNGSTIC ACID
• CATALYTIC-OXIDATION
• PERTURBATION-THEORY
• H2O2
• HYDROXYLATION
• EPOXIDATION
• ALKANES

In the present paper, the reaction mechanism corresponding to activation of hydrogen peroxide (H2O2) by a divanadium-substituted polyoxometalate (POM) [gamma-PV2W10O38(mu-OH)(2)](3-) (I) to form catalytic active species, peroxo complex [gamma-PV2W10O38(mu-OH)(2)](3-) (III), was studied by using the density functional theory (DFT) calculations method with B3LYP functional. The results indicate that coordination of H2O2 to I proceeds via a vanadium-center-assisted proton transfer pathway to remove the first water molecule and form a hydroperoxy intermediate [gamma-PV2W10O38(mu-OH) (mu-OOH)](3-) (II). And intermediate 11 occurs through three successive water-assisted proton transfer steps to remove the second water molecule and finally forms catalytic active species. The calculated overall energy profiles show that coordination of H2O2 to vanadium center requires a proton transfer barrier of about 24 kcal mol(-1). A detailed comparison of molecular geometries and electronic structure shows that the catalytic active species has a very interesting structural feature, where a superoxide radical (Of) was embedded into two vanadium centers, and may be a potential nucleophile. The unique withdrawing electron properties and flexible bonding ability of the gamma-Keggin-type POM ligand contribute to the formation of Of radical. The tunable alternate arrangement of W-O bond series in gamma-Keggin-type POM ligand contributes to the flexibility of the gamma-Keggin-type POM ligand. Meanwhile, our DFT calculations show a good performance of B3LYP-gauge-independent atomic orbital (IGAIM) method for the calculation of H-1 NMR parameters of divanadium-substituted phosphotungstate.

• 出版日期2018-10