The Coordinative Bond in Complexes

Although coordination complexes are molecules, units can be identified in atomic solids that behave optically and electronically like fixed molecular complexes although there are no molecules in atomic solids. There are strong interactions among all the atoms in the lattice. The optical spectrum of a chromium dopant in oxide lattices, e.g., in a ruby laser, is like that of chromium coordination complexes in oxidic solvents. 

The spectrochemical series for metal ions and the same surrounding ligand is  

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