All metal ions are Lewis acids since they can coordinate to free electron pairs (i.e., Lewis bases). The outcome of this reaction is called a coordination compound or a complex between the central metal ion (Lewis acid) and the electron donor (Lewis base). A complex is thus composed of ions or molecules that may exist individually in solution, but in combination they produce the coordination compound. The ions or molecules coordinated to the central metal ion are called ligands and make up the coordination sphere. The number of points at which ligands are attached to the metal ion is called the coordination number. The different categories of ligands are shown in Figure 10.2.
Was this article helpful?