A high-quality, 3D ball-and-stick model of calcium octaammine dichloride, chemical formula [Ca(NH₃)₈]Cl₂.  
Central structure: A large, metallic-orange sphere representing the Calcium ion (Ca²⁺) sits at the center. It is coordinated by eight Ammonia (NH₃) molecules. Each NH₃ molecule is depicted as a blue sphere (Nitrogen) with three smaller white spheres (Hydrogen) attached.
 
Coordination geometry: The eight Nitrogen atoms are arranged around the central Calcium in a symmetrical bicapped trigonal-prismatic (or dodecahedral) geometry, clearly showing the 8-coordinate nature.
 
Lattice context: Green spheres representing Chloride ions (Cl⁻) are positioned around the complex cation, connected by faint dashed lines indicating hydrogen bonding.
 
Reversible coordination visualization: On the left side, translucent NH₃ molecules are shown with an inbound arrow, representing ammonia absorption. On the right, NH₃ molecules are shown leaving with an outbound arrow, representing desorption/regeneration back to CaCl₂.
 
Style: Scientific visualization, clean studio lighting, dark gradient background, highly detailed spheres and cylindrical bonds, accurate CPK coloring (Ca: orange, N: blue, H: white, Cl: green), 8K resolution, sharp focus.