Coordination Sphere
The central metal together with the ligands directly attached to it, written inside square brackets.
Formula / equation
[M(L)ₙ]
Unit
Dimensionless
In depth
Species inside the coordination sphere are held by coordinate bonds and are not released on dissolution, so they cannot be precipitated by ordinary reagents. Anything outside the brackets is ionically bound and dissociates freely in water.
Examples in the real world
In [Co(NH₃)₅Cl]Cl₂ only the two outer chlorides precipitate with silver nitrate, not the coordinated one.