On matrix stabilisation of d- and f-transition metal ions in unstable oxidation states

The state-of-the-art in matrix stabilisation of d- and f-transition metal ions in unstable oxidation states is analysed. Main aspects of this problem concerning the genealogy of appropriate matrix systems are classified. Relevant examples are given and the data that contradict the scheme proposed are discussed. The thermodynamics of the matrix stabilisation effect is considered using the concept of isomorphic miscibility. The influence of defects and non-equilibrium on the matrix stabilisation effect is discussed. The problem of identification of the oxidation states in matrix systems is examined and various types of matrix systems are considered.