IGNOU BCHET-147
- Organometallics, Bioinorganic Chemistry, Polynuclear Hyderocarbons and UV, IR Spectroscopy,
Latest Solved Assignment
(January 2024 - December 2024)

PART A: ORGANOMETALLICS, BIOINORGANIC CHEMISTRY

1. Give the reactions where sodium nitroprusside is used for the qualitative analysis for the deterction of S2- and S in organic compounds.

2. Give the differences between organometallic compounds and organic compounds.

3. What is the structure of ferrocene in the solid state? What happens to the structure at extremely low temperature?

4. Explain the structure of Ni(CO)4 based on valence bond approach.

5. With suitable reactions (any two) explain reductive carbonylation.

6. How are binuclear carbonyls characterized? Give the structure of Fe2(CO)9 and explain the different types of bond present in it.

7. Give the following reactions for the formation of:

(i) carbonylate anion by addition of alkali or reduction (any two)
(ii) carbonyl hydrides (any one)
(iii) carbonyls by displacement of CO by other ligands (any two).

8. Discuss the classification of the elements on the basis of mechanism of action.

9. Discuss the importance of cadmium of biological system. Why they cannot harm new bond babies? What is the effect of long term cadmium exposure in animals and human?

10. What are the reactions involved in photosystem I and II. Give the Z-scheme of photosynthesis also.

PART B: POLYNUCLEAR HYDROCARBONS AND UV, IR SPECTROSCOPY

11. Discuss the preparation of the following compounds starting from ethyl 3-oxobutanoate?

i) 2-Butenoic acid (crotonic acid)
ii) 4-ketopentanoic acid

12. Why 1-position (α-position) of naphthalene is more reactive than the 2-position (β-position). Explain.

13. Give IUPAC name of the following compounds:

14. (i) The attack of the electrophile in furan occurs at the C-2 (or α) position. Explain with the help of a suitable example.
(ii) Write the preparation of pyridine.

15. Give the schematic diagram of the order of molecular orbital energies and give the possible electronic transitions in them.

16. Explain bathochromic shift with a suitable example.

17. Explain the electronic spectra of the acetylenic and benzenoid chromophore.

18. Explain the degrees of freedom for polyatomic molecules.

19. i) List different factors which govern the position and intensity of bands appearing in the IR spectrum of an organic compound.
ii) The C–C stretching vibration is infrared inactive (or nearly inactive). Give reason. In which region, C–H stretching absorptions of alkanes are exhibited?

20. Give the characteristics bands observed in the IR spectra of carboxylic acids and carboxylic acid anhydrides.

PART A: ORGANOMETALLICS, BIOINORGANIC CHEMISTRY

1 What is chromyl chloride test? Give suitable equations.

2 Give the suitable equations for the reaction of potassium permanganate in acidic medium with the following:
Sulphuric acid, potassium iodide, ferrous sulphate in acidic medium.

3 What is Zeise’s salt? Give suitable diagram to explain its structure.

4 Explain the structure of Fe(CO)5 based on valence bond approach.

5 If the complex M2(CO)9 is obeying 18 electron rule, then identify the 3d metal in it.

6 Draw the isomers of Co2(CO)8 and give the differences in their structures.

7 Explain with suitable diagrams the synergic bonding in metal carbonyls.

8 Give the classification of the elements according to their occurrence in three different biological environments.

9 Give the main reactions in photosynthesis.

10 Explain the conversion of heme to hemin along with suitable diagrams.

PART B: POLYNUCLEAR HYDROCARBONS AND UV, IR SPECTROSCOPY

11 Discuss the preparation of ethyl 3-oxobutanoate starting from ethyl ethanoate. Also write the mechanism of this reaction.

12 By giving a suitable example, write the mechanism of electrophilic substitution reaction of naphthalene.

13 Which one is more basic-pyrrole or pyridine? Explain.

14 (a) Explain why nucleophilic substitution is taken place mainly and 2 and 4-positions of pyridine?
(b) Complete the following reactions:

15 What are auxochromes? Give suitable examples from small organic molecules to explain this.

16 What are the two main parameters on which the characteristics of the absorption bands in ultraviolet and visible spectra depends on? Also explain in what ways the intensity of absorption can be expressed.

17 With suitable diagram give the transitions that are observed in the electronic spectra of the carbonyl chromophore.

18 Which of the following molecules absorbs at the longer wavelength?

19 Why the band for –C ≡N has greater intensity than that of the –C ≡C– group in the 2500 – 2000 cm-1 region of the IR spectrum?

20 What are the main absorption bands in the IR spectra of aldehydes and ketones ? Giving suitable examples, discuss the effect of conjugation on the carbonyl stretching frequency in aldehydes and ketones.