complex ion

A **complex ion** is a charged species consisting of a central metal atom or ion bonded to a set of surrounding molecules or anions called ligands. These ligands donate electron pairs to the metal center, forming coordinate covalent bonds. Complex ions play a crucial role in coordination chemistry, influencing the properties and reactivity of metals in biological systems, industrial processes, and catalysis. Examples include [Fe(CN)₆]³⁻ and [Cu(NH₃)₄]²⁺. Understanding complex ions is essential for studying metal-ligand interactions and their applications in various scientific fields.