Abstract
This chapter reviews recent advances in the development of discrete polynuclear spin‐crossover (SCO) complexes of d
4
‐d
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metal ions published from 2004–2011 inclusive. Synthesis of discrete polynuclear complexes is achieved by one of two approaches. The first, controlled/designer‐ligand, approach involves use of polydentate ligands with desired number of metal ion binding pockets. The second, supramolecular, approach involves the use of a combination of simpler blocking/capping and bridging ligands that are either easily accessed or commercially available. Whilst a large number of new discrete polynuclear SCO complexes of iron have been reported, including dinuclear iron(II) complexes, higher nuclearity iron(II) compounds, and iron(III) complexes, no new examples featuring cobalt(II) or cobalt(III) complexes and chromium(II) complexes have been reported. The chapter presents a discussion on these new SCO‐active iron(II) and iron(III) complexes, and describes the new studies on the existing SCO‐active cobalt(II) and chromium(II) complexes.