+A **complex ion** is a central metal atom or ion bonded to a surrounding group of molecules or ions, known as [ligands](/wiki/ligand), through coordinate bonds. These unique structures often impart vivid [colors](/wiki/color) to solutions and compounds, playing a key role in various chemical and biological processes.
+## See also
+- [Coordination Chemistry](/wiki/coordination_chemistry)
+- [Transition Metal](/wiki/transition_metal)
+- [Ligand](/wiki/ligand)
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