Ion-pairing in polyoxometalate chemistry: impact of fully hydrated alkali metal cations on properties of the keggin [PW₁₂O₄₀]³⁻anion

Abstract

is characterized as a "hydrated" ion-pair complex. However, for M = Rb and Cs, it is a "contact" ion-pair complex, where the strong anion-cation interaction makes it a better electron acceptor than the "hydrated" ion-pair complexes. Remarkably, the electronic excitations in the visible part of the absorption spectrum of these complexes are predominantly solvent-to-POM charge transfer transitions (i.e. intermolecular CT). The ratio of the number of intermolecular charge transfer transitions to the number of O(2p)-to-W(5d) valence (i.e. intramolecular) transitions increases with the increasing atomic number of the alkali metals.

Topics & Concepts