Complex Ion
A charged species consisting of a central metal ion surrounded by a definite number of ligands.
Formula / equation
[ML₆]ⁿ⁺
Unit
Dimensionless
In depth
The complex ion is written inside square brackets, and its overall charge is the sum of the metal's oxidation state and the charges of its ligands. Because the coordinate bonds survive dissolution, the free metal ion concentration in solution is vanishingly small.
Examples in the real world
[Fe(CN)₆]³⁻, [Ag(NH₃)₂]⁺, and the deep blue [Cu(NH₃)₄]²⁺ formed when ammonia is added to copper sulfate.