Figure : The Prussian White material with its cubic and rhombohedral crystal structures. In these structures, the high-spin transition-metal ion is represented by a red sphere, the low-spin transition-metal ion is represented by a green sphere. Coordination polyhedra were made slightly transparent, colored in accordance with the color of their central atom. The nitrogen atoms are represented by a blue sphere, the carbon atoms by a grey sphere, and the sodium atoms by a yellow sphere.