Learn about coordination compounds, their structure, nomenclature, coordination numbers, and ligand types. Discover their essential applications in medicine, industry, and catalysis. Perfect for students and chemistry enthusiasts!
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Table of contents
- Definition and Nomenclature of Coordination Compounds
- Coordination Number and Ligands
- Applications in Medicine and Industry.
Coordination Compounds: Structure, Properties, and Applications
Coordination compounds play a vital role in chemistry, medicine, and industry. These unique compounds consist of a central metal atom or ion surrounded by molecules or ions called ligands, forming a complex structure. Their applications range from life-saving medicines to industrial catalysts.
1. Definition and Nomenclature of Coordination Compounds
What Are Coordination Compounds?
A coordination compound is a compound in which a central metal atom or ion is bonded to surrounding molecules or ions called ligands through coordinate covalent bonds. These compounds are commonly found in nature, biological systems, and industrial applications.
Nomenclature of Coordination Compounds
Naming coordination compounds follows specific rules set by the IUPAC (International Union of Pure and Applied Chemistry):
- Name the ligands first (in alphabetical order), followed by the metal ion.
- Use prefixes (mono-, di-, tri-, etc.) to indicate the number of ligands.
- If the complex ion is an anion, the metal’s name ends in “-ate” (e.g., Ferrate for Fe, Cuprate for Cu).
- Oxidation state of the metal is written in Roman numerals in parentheses.
Examples:
- [Cu(NH₃)₄]²⁺ → Tetraamminecopper(II) ion
- K₃[Fe(CN)₆] → Potassium hexacyanoferrate(III)
2. Coordination Number and Ligands
Coordination Number
The coordination number refers to the number of ligand donor atoms bonded to the central metal ion. Common coordination numbers include:
- 2 (Linear) – Example: [Ag(NH₃)₂]⁺
- 4 (Tetrahedral/Square planar) – Example: [Ni(CN)₄]²⁻
- 6 (Octahedral) – Example: [Fe(CN)₆]³⁻
Types of Ligands
Ligands are classified based on how many donor atoms they contribute:
- Monodentate Ligands – Bind through a single donor atom (e.g., Cl⁻, NH₃, H₂O).
- Bidentate Ligands – Bind through two donor atoms (e.g., Ethylenediamine, C₂O₄²⁻).
- Polydentate Ligands – Bind through multiple donor atoms (e.g., EDTA⁴⁻).
3. Applications of Coordination Compounds
In Medicine
- Cisplatin ([Pt(NH₃)₂Cl₂]) – A widely used anticancer drug.
- Vitamin B12 (Cobalt complex) – Essential for red blood cell production.
In Industry
- Catalysis – Complexes like [V₂O₅] are used in industrial reactions.
- Dyeing and Pigments – Metal complexes give bright colors to textiles.
- Extraction of Metals – Cyanide complexes help extract gold and silver.
Conclusion on Coordination Compounds
Coordination compounds are essential in many aspects of science and industry. Their ability to form stable structures with metals makes them invaluable in medicine, catalysis, and materials science. Understanding their properties and applications is crucial for students and researchers alike.
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Revision Questions and Answers on Coordination Compounds
Question 1:
What is a coordination compound?
Answer:
A coordination compound consists of a central metal atom or ion bonded to surrounding molecules or ions called ligands through coordinate covalent bonds. These compounds play essential roles in biological systems, medicine, and industry.
Question 2:
What is a coordination number? Give an example.
Answer:
The coordination number is the number of ligand donor atoms directly attached to the central metal ion in a coordination complex.
Example: In [Fe(CN)₆]³⁻, the coordination number of Fe³⁺ is 6 because it is bonded to six cyanide (CN⁻) ligands.
Question 3:
Differentiate between monodentate, bidentate, and polydentate ligands with examples.
Answer:
- Monodentate ligands bind to the metal through one donor atom (e.g., NH₃, Cl⁻, H₂O).
- Bidentate ligands bind through two donor atoms (e.g., Ethylenediamine, C₂O₄²⁻).
- Polydentate ligands bind through multiple donor atoms (e.g., EDTA⁴⁻).
Question 4:
What is the IUPAC name of [Cu(NH₃)₄]²⁺?
Answer:
The IUPAC name of [Cu(NH₃)₄]²⁺ is Tetraamminecopper(II) ion. The ligand (NH₃) is named first, followed by the metal (Copper) with its oxidation state (II) in Roman numerals.
Question 5:
Give two important applications of coordination compounds.
Answer:
- In Medicine: Cisplatin ([Pt(NH₃)₂Cl₂]) is used as an anticancer drug.
- In Industry: Coordination compounds are used as catalysts in chemical processes, such as in the production of ammonia using the Haber process.