CSIR NET Chemical Science: Coordination Chemistry - Most Important Questions! (Download PDF)

Coordination Chemistry - Most Important Questions! (Download PDF)

1. The order of reactivity of ligands NMe3, PMe₃ and CO with complexes MeTiCl₃ and (CO)₅Mo(Ph) are: 

1. Co > PMe₃ > NMe₃ and CO > NMe₃ > PMe₃ 
2. PMe₃ > CO > NMe₃ and NMe₃ > CO > PMe₃ 
3. NMe₃ > PMe₃ > CO and CO > PMe₃ > NMe₃ 
4. NMe₃ > CO > PMe₃ and PMe₃ > NMe₃ > CO

2. The reaction of PtCl₄ with NH₃ gives product A while its reaction with [NO₂]^-2 followed by NH₃ gives product B. The A and B respectively, are: 

1. Trans-[Pt(NH₃) Cl₂] and trans-[Pt(NH₃) Cl₂(NO₂)]-
2. Cis-[Pt(NH₃) Cl₂] and trans-[Pt(NH₃) Cl₂(NO₂)]-
3. Cis-[Pt(NH₃) Cl2] and cis-[Pt(NH₃) Cl₂(NO₂)]-
4. Trans-[Pt(NH₃) Cl₂] and cis-[Pt(NH₃) Cl₂(NO₂)]-

3. CFAE is also known as: 

1. The difference between CFSE of reactant and product 
2. The difference between CFSE of reactant and intermediate 
3. The Difference between CFSE of product and intermediate 
4. The CFSE of reactant only

4. Consider the following reaction: 

1. [Cr (H₂O)₆] ⁺² + [CO Cl (NH₃)5] ⁺² → [Co(NH₃)5H₂O] ⁺² + [Cr Cl (H₂O)₅] ⁺² 
2. [Fe(CN)₆]^-4 + [Mo(CN)₈]^-3 → [Fe(CN)₆]^-3 + [Mo(CN)₈]^-4 

Which one of the following is the correct statement?

1. Both involve an inner sphere mechanism.
2. Both involve an outer sphere mechanism.
3. Reaction (i) follows an inner sphere and reaction (ii) follows outer sphere mechanism.
4. Reaction (i) follows an outer sphere and reaction (ii) follows an inner sphere mechanism.

5. The correct order of Trans effect is: 

1. H- > SCN- > H2O 
2. CO > C₂H₅ > Py > H₂O 
3. C6H5- > I- <Py > -OH
4. CO > H₂O > CH₃ > Py > CN

6. Mention the correct statement: 

1. Complexes having sp³d² hybridization have strong bonds than the complexes having d²sp³
2. Complexes having d²sp³ hybridization have strong bonds than the complexes having sp³d²
3. Both have equal bond strength 
4. It cannot be decided

7. [Co(NH₃)₅X] ⁺² + H₂O→ [Co(NH₃)₅(H₂O)] ⁺³ + X^- 

Mention the correct statement about the above reaction 

1.  It is found to be second order
2.  It is found to be zero order 
3.  H2O is involved in rate-determining step
4.  H2O does not affect the rate of reaction

8. Which of the following statements is/are true about Sn1 reactions? 

(I) In S_n1 mechanism, the rate-determining the slowest step is the metal-ligand bond-breaking step. 

(II) In S_n1 mechanism, the rate-determining the slowest step is the metal-ligand bond making step.

(III) In S_n1 mechanism, the coordination no. of the complex is decreased from 6 to 5.

1. I and II 
2. I and III 
3. I, II and III
4. Only I

9. The substitutionally inert complex ion amongst the following is: 

1. [Cr (H2O₆] ⁺³  
2. [Fe (H2O)₆] ⁺² 
3. [Cr (H2O)₆] ⁺² 
4. [Ni (H2O)₆] ⁺²

10. The reaction is an example of: 

[Co(NH₃)₅Cl] + + Hg⁺²→[Hg(NH₃)₅Cl] + +Co⁺² 

1. Electrophilic substitution reaction
2. Nucleophilic substitution reaction 
3. Electrophilic addition reaction
4. Nucleophilic addition reaction

Solutions

Solution 1: 

For (CO)₅Mo(Ph), those ligands whose -acidity is more will react faster and thus have more reactivity. Since we know that, order of -acidity is CO > PMe₃ > NMe₃ so, the same is the order of reactivity here.

Solution 2: 

The reaction given follows the Trans-effect.

The order of trans effect is as follow: NO₂ > Cl > NH₃

So, when PtCl₄ reacts with NH₃, first NH₃ replaces one Cl; and second NH₃ goes to trans of Cl since trans effect of Cl > NH₃

Similarly, when PtCl4 reacts with [NO₂]^-2, it replaces one Cl. Thereafter, reaction with NH3 makes NH3 to occupy position trans to [NO₂]^-2 because of the trans effect of NO₂ > Cl > NH₃.

Solution 3: 

Solution 4: 

In reaction (i), bridged activated complex is formed. Also, group transfer occurs.

While in reaction (ii), no bridging ligand is present and no group transfer occurs. It is also a type of Cross reaction. 

Solution 5: 

The order of trans-effect is: CN > CO > NO > C₂H₅ > PR₃ > H > C₆H₅ > NO₂ > I > SCN > Br > Cl > Py > NH₃ > OH > H₂O

Solution 6: 

Complexes having d²sp³ hybridisation involves use of inner orbitals, thus form strong bonds whereas complexes having sp3d2 hybridisation involves use of outer orbitals and are much less strong than outer orbital complexes.

Solution 7: 

It is an example of an acid hydrolysis reaction.

The rates of hydrolysis of reactions of this type have been studied and found to be FIRST ORDER reactions. 

Since in aqueous solution, concentration of water is always constant, the effect of changes in water concentration on rate of reaction cannot be determined.

Rate law for this reaction becomes: rate = k'Co NH₃5X+2[ H₂O]. Thus, the rate law does not tell us whether water is involved in rate-determining step.

Solution 8: 

Solution 9: 

Order of inertness is: L.S. Oh > d³ = d⁸ (Oh H.S. and L.S.) > d⁴ (Oh L.S.) > d⁵ (Oh L.S.)

Cr⁺³ is d³ Fe⁺² is d⁶ Cr⁺² is d4 Ni⁺² is d₈

So, Cr⁺³ is most inert of all.

Solution 10: 

Hg⁺² substitutes Cobalt in this reaction and becomes Hg(0) indicating it’s an Electrophilic Substitution Reaction.

Answer Key:

1. C
2. B
3. B
4. C
5. B
6. B
7. D
8. D
9. A
10. A

Download Important Questions on Coordination Chemistry - Download PDF Here

Check Out: 

• Study Notes for CSIR NET Chemical Science - Download PDF Here!
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• Chemical Science Formula Sheets for CSIR-NET [Free] - All Important Formulas at One Place!

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