An overview on the electronic structure of transition metal cyanide-based materials from XPS data

Transition-metal cyanides constitute a versatile family of coordination complexes characterized by interesting physical and functional properties. Such features are determined by the ability of that ligand to serve as an electron density bridge between the involved transition metal centers and the diversity of coordination modes for the cyanide ligand (CN¯). In fact, such an ability results in a coupling and overlapping of the involved metals' electron clouds. In that context, X-ray photoelectron spectroscopy (XPS) appears as an excellent tool for probing the interaction of the CN bridge with the bridged metal centers, the electron density on these last ones, their effective valence, the electron density redistribution, and many other features related to the electronic structure of these solids. This review discusses the scope of XPS for probing the electronic structure of the titled family of coordination polymers. Understanding the scope of this spectroscopic technique for studying these materials opens new opportunities to engineer their potential applications. • Transition metal cyanides; emerging wide band gap semiconductors; spin crossover materials.