Definitions [9]
Isomerism is the phenomenon in which compounds have the same molecular formula but differ in their physical or chemical properties due to a different arrangement of atoms or groups in space or structure.
Define the term Hydrated isomers.
Isomers in which there is exchange of solvent (water) ligands between coordination and ionization spheres are called hydrate isomers.
Define Distereoisomers.
Two or more coordination compounds which contain the same number and types of atoms, and bonds (i.e., the connectivity between atoms is the same), but which have different spatial arrangements of the atoms are called distereoisomers.
Define the term Co-ordination isomer.
Isomers which show interchange of ligands between cationic and anionic spheres of different metal ions are called co-ordination isomers.
Define the term Hydrated isomers.
Isomers in which there is exchange of solvent (water) ligands between coordination and ionization spheres are called hydrate isomers.
Isomerism is the phenomenon in which compounds have the same molecular formula but differ in their physical or chemical properties due to a different arrangement of atoms or groups in space or structure.
Define Distereoisomers.
Two or more coordination compounds which contain the same number and types of atoms, and bonds (i.e., the connectivity between atoms is the same), but which have different spatial arrangements of the atoms are called distereoisomers.
Define the term Co-ordination isomer.
Isomers which show interchange of ligands between cationic and anionic spheres of different metal ions are called co-ordination isomers.
Define the following term:
Anomers
Anomers are stereoisomers of sugars that differ only in the configuration of the hydroxyl group at the C1 position. They are not mirror images of each other.
Key Points
| Main Type | Subtype | Description | Example |
|---|---|---|---|
| Stereoisomerism | Geometrical isomerism | Different spatial arrangement (cis–trans) | [Pt(NH₃)₂Cl₂] |
| Optical isomerism | Non-superimposable mirror images | [Co(en)₃]³⁺ | |
| Structural isomerism | Ionisation isomerism | Exchange of ions inside/outside the coordination sphere | [Co(NH₃)₅SO₄]Br and [Co(NH₃)₅Br]SO₄ |
| Linkage isomerism | Ligand attaches through different donor atoms | [Co(NH₃)₅NO₂]Cl₂ and [Co(NH₃)₅ONO]Cl₂ | |
| Coordination isomerism | Exchange of ligands between complex ions | [Co(NH₃)₆][Cr(CN)₆] and [Co(CN)₆][Cr(NH₃)₆] | |
| Solvate isomerism | Exchange of solvent molecules | [Cr(H₂O)₆]Cl₃ and [Cr(H₂O)₅Cl]Cl₂·H₂O |
| Main Type | Subtype | Description | Example |
|---|---|---|---|
| Stereoisomerism | Geometrical isomerism | Different spatial arrangement (cis–trans) | [Pt(NH₃)₂Cl₂] |
| Optical isomerism | Non-superimposable mirror images | [Co(en)₃]³⁺ | |
| Structural isomerism | Ionisation isomerism | Exchange of ions inside/outside the coordination sphere | [Co(NH₃)₅SO₄]Br and [Co(NH₃)₅Br]SO₄ |
| Linkage isomerism | Ligand attaches through different donor atoms | [Co(NH₃)₅NO₂]Cl₂ and [Co(NH₃)₅ONO]Cl₂ | |
| Coordination isomerism | Exchange of ligands between complex ions | [Co(NH₃)₆][Cr(CN)₆] and [Co(CN)₆][Cr(NH₃)₆] | |
| Solvate isomerism | Exchange of solvent molecules | [Cr(H₂O)₆]Cl₃ and [Cr(H₂O)₅Cl]Cl₂·H₂O |
- Proposed by Heitler and London (1927), further developed by Pauling and Slater.
- A covalent bond is formed when half-filled valence atomic orbitals of similar energies overlap, each containing one unpaired electron.
- Greater the overlap → stronger the bond.
Types of Orbital Overlap:
| Type | Description | Bond Formed |
|---|---|---|
| Axial (Head-on) overlap | Orbitals overlap along the internuclear axis | Sigma (σ) bond |
| Sidewise (Lateral) overlap | Orbitals overlap parallel to each other, perpendicular to the internuclear axis | Pi (π) bond |
Hybridisation & Shapes:
| Hybridisation | Shape | Coordination No. |
|---|---|---|
| sp³ | Tetrahedral | 4 |
| dsp² | Square planar | 4 |
| sp³d | Trigonal bipyramidal | 5 |
| d²sp³ | Octahedral (inner) | 6 |
| sp³d² | Octahedral (outer) | 6 |
- d-orbitals of metal ion split into lower and higher energy levels in the presence of ligands
- In a free ion, d-orbitals are degenerate (same energy)
- Spectrochemical Series
I⁻ < Br⁻ < Cl⁻ < S²⁻ < F⁻ < OH⁻ < C₂O₄²⁻ < H₂O < NCS⁻ < EDTA < NH₃ < en < CN⁻ < CO
- d-orbitals split into t₂g (low) and eg (high) energy levels
- The energy difference lies in the visible region
- Electron jumps from t₂g to eg energy level, which is called d–d transition.
- d¹ to d⁹ ions → coloured
- d⁰ and d¹⁰ ions → colourless
Concepts [17]
- Concept of Coordination Compounds
- Some Important Terms Pertaining to Coordination Compounds
- Werner’s Theory of Coordination Compounds
- Nomenclature of Coordination Compounds - Formulas of Mononuclear Coordination Entities
- Nomenclature of Coordination Compounds - Naming of Mononuclear Coordination Compounds
- Isomerism in Coordination Compounds
- Isomerism in Coordination Compounds
- Stereoisomerism
- Structural Isomerism
- Bonding in Coordination Compounds
- Bonding in Coordination Compounds
- Valence Bond Theory (VBT)
- Magnetic Properties of Coordination Compounds
- Crystal Field Theory (CFT)
- Colour in Coordination Compounds
- Bonding in Metal Carbonyls
- Importance and Applications of Coordination Compounds
