Cyanide-Bridged Molecular Squares - The Building Units of Prussian Blue

Cyanide-bridged molecular squares offer a unique opportunity for study, as they represent a model of the simplest unit of Prussian blue and allow access to a wide range of physical properties that can be monitored, such as rich electrochemistry, valence- and spin-state control, and spin-crossover phenomena. This microreview presents recent findings in the field of cyanide squares with particular focus on their syntheses and physical properties.