Manganese clusters: a common ground for photosynthesis, quantum tunnelling of the magnetization and colossal magnetoresistance

Mixed-valence manganese clusters are briefly reviewed, showing their relevance to such diverse fields as metalloenzymes and metalloproteins, single-molecule magnets, and colossal magnetoresistance. Particular emphasis has been given to the possibility of using high-field EPR spectroscopy for obtaining structural information from EPR-silent ions such as manganese(III). Besides the small clusters, comprising two-four metal ions relevant to biological systems, a large interest is invested in larger clusters, with the aim of showing how synthetic work aimed at obtaining models for biological clusters has provided many interesting results for other types of investigations.