Chemistry: Comprehensive NEET Chemistry Coordination Compounds Formulae Summary

1. Coordination Compounds

1.1 Werner’s Theory of Coordination Compounds

• Formula: $\text{Complex Compound}=[\text{Central Metal Ion}(\text{Ligands})]\text{Counter Ion}$
• Explanation: In coordination compounds, the central metal ion is bonded to a fixed number of ligands. Werner’s theory differentiates between primary valences (ionizable, satisfied by negative ions) and secondary valences (non-ionizable, satisfied by ligands).

1.2 Nomenclature of Coordination Compounds

• Formula: ${\text{[Co(NH}}_3{\text{)}}_6{]}^{3+}$
• Explanation: The IUPAC naming involves listing ligands alphabetically followed by the central metal with its oxidation state. Ligands are named with prefixes such as di-, tri-, and their order does not depend on their charge.

2. Chemical Bonding in Coordination Compounds

2.1 Valence Bond Theory (VBT)

• Formula: Hybridization (e.g., $s{p}^3,ds{p}^2,s{p}^3{d}^2$) determines the geometry.
• Explanation: VBT explains the bonding in terms of the hybridization of atomic orbitals in the central metal ion. For example, $[Ni(CN{)}_4{]}^{2-}$ is square planar due to $ds{p}^2$ hybridization, leading to diamagnetism.

2.2 Crystal Field Theory (CFT)

• Formula: ${\Delta }_0=\text{Energy difference between }{e}_g\text{ and }{t}_{2g}\text{ orbitals}$
• Explanation: CFT explains the splitting of d-orbitals in a ligand field, leading to different electronic arrangements and properties. Strong field ligands cause large splitting (${\Delta }_0>P$), leading to low spin complexes.

Did You Know?

The splitting of d-orbitals in an octahedral field leads to the formation of $t_{2g}$ and $e_g$ orbitals, where the energy separation (${\Delta }_0$) dictates whether the complex is high-spin or low-spin.

3. Isomerism in Coordination Compounds

3.1 Geometrical Isomerism

• Formula: $\text{cis/trans isomerism in }[M{X}_2{L}_2]$ where X and L are ligands.
• Explanation: Geometrical isomerism occurs due to different spatial arrangements of ligands around the central metal ion, leading to different properties despite having the same chemical formula.

3.2 Optical Isomerism

• Formula: ${\text{[Co(en)}}_3{]}^{3+}$
• Explanation: Optical isomers are non-superimposable mirror images that rotate plane-polarized light in different directions (dextro and laevo).

Common Misconception:

Not all coordination compounds exhibit optical isomerism. Only those with chiral centers, typically involving bidentate ligands like $\text{en}$ (ethylenediamine), can have optical isomers.

4. Applications and Importance of Coordination Compounds

4.1 Role in Biological Systems

• Formula: ${\text{[Fe(CN)}}_6{]}^{4-}$
• Explanation: Coordination compounds play crucial roles in biological systems, such as chlorophyll (a coordination compound of magnesium) and hemoglobin (a coordination compound of iron).

Real-life Application:

Coordination compounds like ${\text{[Ag(CN)}}_2{]}^{-}$ are used in silver plating and gold extraction, highlighting their industrial significance.

5. Practice Questions

Question 1:

• Problem: Calculate the magnetic moment of ${\text{[NiCl}}_4{]}^{2-}$.
• Solution: $\mu =\sqrt{n(n+2)},\text{BM}$, where $n$ is the number of unpaired electrons. For ${\text{Ni}}^{2+}$ with two unpaired electrons, $\mu =2.83,\text{BM}$.

Question 2:

• Problem: Write the IUPAC name for ${\text{[Co(NH}}_3{\text{)}}_6]{\text{Cl}}_3$.
• Solution: Hexaamminecobalt(III) chloride.

Question 3:

• Problem: Differentiate between the geometrical isomers of ${\text{[Pt(NH}}_3{\text{)}}_2{\text{Cl}}_2]$.
• Solution: The cis-isomer has adjacent chloride ions, while the trans-isomer has opposite chloride ions.

This summary is designed to aid quick revision of key concepts and formulae in coordination chemistry, focusing on essential principles and their applications relevant to NEET preparation.