Gujarat BoardEnglish MediumSTD 12 ScienceChemistryCoordination Compounds4 Marks
Question
Explain different types of Structural isomerism with example.
✓
Answer
(1) Linkage Isomerism: → Linkage isomerism arises in a coordination compound containing ambidentate ligand. → A simple example is provided by complexes containing the thiocyanate ligand, NCS-, which may bind through the nitrogen to give M-NCS or through sulphur to give M-SCN. → Jorgenson discovered such behaviour in the complex $\left[ Co \left( NH _3\right)_5\left( NO _2\right)\right] Cl _2$, which is obtained as the red form, in which the nitrite ligand is bound through oxygen ( - ONO ), and as the yellow form, in which the nitrite ligand is bound through nitrogen $\left(- NO _2\right)$. $\begin{array}{l}\text { e.g. : }\left[ Co ( ONO )\left( NH _3\right)_5\right]^{2+} \text { and }\left[ Co \left( NO _2\right)\left( NH _3\right)_5\right]^{2+} \\ \quad \quad \quad \quad \text{Red} \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad\text{Yellow} \\\end{array}$ (2) Coordination Isomerism: → This type of isomerism arises from the interchange of ligands between cationic and anionic entities of different metal ions present in a complex. e.g. : $\left[ Co \left( NH _3\right)_6\right]\left[ Cr ( CN )_6\right]$, and $\left[ Cr \left( NH _3\right)_6\right][ Co ( CN )_6$] (3) Ionisation Isomerism: → This form of isomerism arises when the counter ion in a complex salt is itself a potential ligand and can displace a ligand which can then become the counter ion. e.g. : $\begin{aligned} & \left.\left. [Co \left( NH _3\right)_5\right]\left( SO _4\right)\right] Br \text { and }\left[ Cr \left( NH _3\right)_5 Br \right] SO _4 \\ & {\left[ Pt \left( NH _3\right)_4 Cl _2\right] Br _2 \text { and }\left[ Pt \left( NH _3\right)_4 Br _2\right] Cl _2 } \\ & {\left[ Cr \left( NH _3\right)_4 Cl _2\right] NO _2 \text { and }\left[ Cr \left( NH _3\right)_4 Cl \cdot NO _2\right] Cl }\end{aligned}$ (4) Solvate Isomerism OR Hydrate isomerism: → This form of isomerism is known as 'hydrate isomerism' in case where water is involved as a solvent. → This is similar to ionization isomerism. → Three isomeric forms of $CrCl _3 \cdot 6 H _2 O$ are known (1) $\left[ Cr \left( H _2 O \right)_6\right] Cl _3$ (violet). (2) $\left[ Cr \left( H _2 O \right)_5 Cl \right] Cl _2 \cdot H _2 O$ (grey green). (3) $\left[ Cr \left( H _2 O \right)_4 Cl _2\right] Cl \cdot 2 H _2 O$ (green)
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.