Coordination Chemistry – NEET Chemistry Class 12

Coordination Chemistry focuses on complex compounds where a central metal atom or ion binds to ligands. This chapter is crucial for NEET because questions frequently test nomenclature, bonding, geometries, and isomerism of complexes.

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Introduction to Coordination Compounds

• Definition: Compounds containing a central metal atom/ion bonded to ligands via coordinate covalent bonds.

• General Formula: [Metal(Ligand)n]ⁿ⁺

• Importance: Understanding coordination compounds is essential for bioinorganic chemistry, industrial catalysts, and analytical chemistry.

Ligands and Coordination Number

• Ligands: Atoms, ions, or molecules donating electron pairs to the metal.

  • Types: Monodentate, Bidentate, Polydentate (chelating ligands)

• Coordination Number: Number of ligand donor atoms attached to the central metal

  • Common coordination numbers: 2, 4, 6

• Examples:

  • [Fe(CN)₆]³⁻ → hexacyanoferrate, coordination number = 6

  • [Cu(NH₃)₄]²⁺ → tetraamminecopper, coordination number = 4

Nomenclature of Coordination Compounds

• Rules:

  • Ligands named first, then metal

  • Anionic ligands end with ‘o’ (e.g., chloro, cyano)

  • Neutral ligands keep original name (e.g., ammonia, water)

  • Oxidation state of metal given in Roman numerals

• Example: [Co(NH₃)₆]Cl₃ → Hexaamminecobalt(III) chloride

Isomerism in Coordination Compounds

1. Structural Isomerism:

   • Ionization, hydration, linkage, coordination sphere isomerism

2. Stereoisomerism:

   • Geometrical (cis/trans, facial/meridional)

   • Optical isomerism (non-superimposable mirror images)

• Isomerism affects physical and chemical properties and is commonly asked in NEET.

Bonding Theories

1. Werner’s Theory:

   • Primary and secondary valencies explain coordination number and ligand attachment

2. Valence Bond Theory (VBT):

   • Explains hybridization (sp³, dsp², d²sp³) and magnetic properties

3. Crystal Field Theory (CFT):

   • Explains color, magnetic behavior, and stability

   • Splitting of d-orbitals in octahedral, tetrahedral, and square planar complexes

Importance for NEET Preparation

• Questions often include nomenclature, isomerism, and bonding theory.

• Understanding coordination numbers, ligand types, and hybridization is crucial.

• Real-life examples (bioinorganic compounds like hemoglobin, vitamin B₁₂, industrial catalysts) are commonly asked.

Previous Year NEET Questions – Insights

• Naming of coordination compounds and identification of ligands

• Identifying isomers (structural and stereoisomers)

• Predicting magnetic properties using VBT or CFT

• Explaining geometries and hybridization of central metal ions

• Application-based questions in biological and industrial contexts

Study Tips for Students

1. Memorize Ligand Names and Charges – Helps in naming and formula writing.

2. Understand Coordination Number and Geometry – Crucial for predicting structure.

3. Practice Isomerism Problems – Stereoisomers and structural isomers.

4. Learn Werner, VBT, and CFT Basics – Explains bonding and properties.

5. Solve Previous Year NEET Questions – Reinforces concepts and exam pattern familiarity.

Conclusion

Mastering Coordination Chemistry is essential for NEET success. It helps students solve complex nomenclature and isomerism problems, understand bonding and properties of complexes, and answer application-based questions confidently. A strong understanding ensures high scoring potential in inorganic chemistry.