Spin‐State Switching in Solution

This chapter focuses on solution studies of systems where spin events are localized to single, isolated metal centers. It summarizes the kinds of information, such as spin-crossover (SC), and methods available for solution-phase spin switching investigations. The methods include NMR characterization, SQUID magnetometry, and electronic absorption spectroscopy. The chapter surveys recent literature, focusing on effects of solvent and ions, ligand distortions and complex isomerizations, and noncoordinating anion-cation interactions on spin-state switching behavior. It finally highlights several challenges and opportunities of spin-state switching in solution. Solution investigations presented in the chapter emphasize chemical-interaction-based spin-state switching. Spin-state switching in solution is sensitive to small environmental changes. Extensive efforts have been devoted to exploring the influence of solvent, anions and/or salts on SC properties, and some useful structure-property correlations have been obtained.