Spin crossover -: An overall perspective

In this chapter an outline is presented of the principal features of electronic spin crossover. The development of the subject is traced and the various modes of manifestation of spin transitions are presented. The role of cooperativity in influencing solid state behaviour is considered and the various strategies to strengthen it are addressed along with the chemical and physical perturbations which affect crossover behaviour. The role of intermediate spin states is discussed together with spin crossover in five-coordinate systems. The various techniques applied to monitoring a transition are presented briefly. An introduction to theoretical treatments is given and likely areas for future developments are suggested. Relevant review articles in the field are listed and reference to later chapters in the series is given where appropriate.