Electrostatic interactions within mixed-valent compounds

The electrochemical properties of bi- and multi-metallic compounds are a convolution of several factors, among which through-bond electron transfer and through-space electrostatic features are the most prominent. Whereas optical and vibrational properties, and to a growing extent computational studies, are able to probe the 'electronic coupling' aspects of the interactions, determining the extent of electrostatic interaction requires careful experimental and comparative studies. This review highlights the methods that can be used to identify and assess, at least qualitatively, the nature of the often less well explored electrostatic contributions to the electrochemical behavior of such multiredox systems. Therefore, advances in finding reliable models for intramolecular electrostatic interactions are recapitulated. In addition, inter-and intra-molecular influences on the electrostatic properties as well as the exploitation of different ion-pairing capabilities of various electrolytes in order to gain information on electrostatic repulsion energies are discussed. (C) 2018 Published by Elsevier B.V.