structural isomers
Isomers that contain the same number of atoms of each kind but differ in which atoms are bonded to one another are called structural isomers. Isobutane and n-butane are examples of structural isomers. One kind of isomerism consists of two compounds that have the same empirical formula but differ in the number of formula units present in the molecular formula. An example in coordination compounds is two compounds with the empirical formula Pt NH 3 2Cl2. One is a simple square planar platinum II complex, Pt NH3 2Cl2, and the other is an ionic compound that contains the [Pt NH 3 4]2+ cation and the [PtCl4]2 anion, [Pt NH3 4][PtCl4]. As you might expect, these compounds have very different physical and chemical properties. One arrangement of the Cl and NH3 ligands around the platinum ion in the former gives the anticancer drug cisplatin, whereas the other arrangement has no known biomedical applications.