Study Guides/Chemistry/Heteroleptic Complex in Coordination Chemistry
Study Guide · Chemistry

Heteroleptic Complex — Definition and Examples

In coordination chemistry, complexes are classified based on the type of ligands attached to the central metal atom. A Heteroleptic Complex contains two or more different types of ligands.

Question (Click to Flip)

How do you determine if a complex is homoleptic or heteroleptic?

Answer

Simply count the types of ligands. If all ligands are the same — homoleptic. If there are 2 or more different ligand types — heteroleptic.

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Key Facts

Heteroleptic complexes often show geometrical (cis-trans) isomerism because the different ligands can be arranged in different spatial orientations. Homoleptic complexes rarely show this type of isomerism.

Definition and Difference

TypeDefinitionExample
Homoleptic ComplexAll ligands are the same type[Co(NH₃)₆]³⁺ (all ligands are NH₃)
Heteroleptic ComplexTwo or more different types of ligands[Co(NH₃)₄Cl₂]⁺ (NH₃ and Cl⁻ are different)

In the heteroleptic example [Co(NH₃)₄Cl₂]⁺, cobalt is surrounded by four ammonia (NH₃) ligands AND two chloride (Cl⁻) ligands — two different types, making it heteroleptic.

Common Examples

  • [Pt(NH₃)₂Cl₂] — Cisplatin (a famous anti-cancer drug) — has NH₃ and Cl⁻ ligands
  • [Fe(CN)₅NO]²⁻ — Has CN⁻ and NO ligands
  • [Co(en)₂Cl₂]⁺ — Has ethylenediamine (en) and Cl⁻ ligands

Cisplatin is perhaps the world's most famous heteroleptic complex — it is one of the most widely used chemotherapy drugs.

Questions and Answers

How do you determine if a complex is homoleptic or heteroleptic?+

Simply count the types of ligands. If all ligands are the same — homoleptic. If there are 2 or more different ligand types — heteroleptic.

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