LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

LM 50

M.Sc. DEGREE EXAMINATION – CHEMISTRY

FOURTH SEMESTER – APRIL 2007

CH 4953 – ADVANCED COORDINATION CHEMISTRY

 

 

Date & Time: 23/04/2007 / 9:00 – 12:00  Dept. No.                                           Max. : 100 Marks

 

Part-A

 

Answer all questions. Each question carries two marks

 

1. How do you infer tetragonal distortion in transition metal complexes by electronic spectroscopy?
2. What is intensity stealing? Mention its consequences.
3. The CN stretching vibrations in cyano complexes occur at higher energy than that of free cyanide ion. Explain.
4. Metal carbonyls are formed by metals in their lower oxidation states. Give reason.
5. What are optically transparent electrodes? Mention their uses.
6. EPR spectra of transition metal complexes are recorded by doping onto diamagnetic host at low temperature. Give reason.
7. The rate constant for outer-sphere ectron transfer in [Fe(H₂O)₆]^2+/3+ is low as compared to that in [Fe(bpy)₃]^2+/3+. Give reason?
8. What is an internal electrochemical standard? Cite two examples.
9. How do the iron center in cytochromes differ from that of Fe-S proteins?
10. What is Wilson’s disease? What chelating agent is used to cure this disease?

 

Part-B

 

Answer eight questions. Each question carries five marks

 

11. Justify the position of CN-in the spectrochemical series with the help of MO theory.
12. What are compartmental ligands? Explain the synthesis of such ligands from phenol and pyridine head units.
13. How is thiocyanato- and isothiocyanato complexes differentiated by IR spectroscopy?
14. What are Orgel diagrams? Construct the Orgel diagram for d^3,8 metal ions in Oh and T_d  geometries.
15. What is spectroelectrochemistry? Explain the application of this technique in the study of cooordination compounds.
16. What is static dynamic Jahn-Teller effect? Explain the method of studying it by spectroscopic method.
17. The epr spectrum of bis(salyciladimine)copper(II) consists of four sets of eleven lines each. Interpret the spectrum and substantiate your result with the help of experimental evidences.
18. Compute D_o values in T_d geometry by angular overlap model.
19. Illustrate the importance of cation-cavity best fit in the synthesis of macrocyclic complexes.
20. Explain Marcus-Hush theory of electron transfer reactions.
21. Explain the mechanism of in “in vivo nitrogen fixation”.
22. Explain the principle of AC polarography. How do you evaluate the reversibility of the redox couple by this technique?

 

 

 

 

 

 

 

 

 

 

 

 

Part-C

 

Answer four questions. Each question carries ten marks

 

23a.  What is coordination template effect? Differentiate between kinetic and thermodynamic  coordination template effects.

1. Explain the synthesis of complexes of Schiff base macrocycles by this method.

24a.  Explain the principle and methodology of cyclic voltammetry.

1. How is the reversibility of a redox couple evaluated by this technique?

25a.  Explain the electronic spectral features of a low-spin d⁶ metal ion in a tetragonally distorted octahedral geometry.

1. How do you evaluate the D_q^xy and D_q^z  values in this geometry.

26a.  Identify the metal orbitals and LGOs suitable for s-bonding in an O_h geometry.  Construct  a qualitative MO energy level diagram for            s-bonding in an O_h geometry.

1. Compare the D_o values of [CoF₆]^3- and [Co(bpy)₃]³⁺ in the light of MO theory.

27a.  Give a brief account of the electronic spectral features of high-spin O_h complexes of transition metal ions.

1. Construct the Orgel diagram for high-spin d⁸ O_h complex. Explain the spectral features of the corresponding low-spin complex with the help of Tanabe-sugano diagram.

28a.  What are cytochromes? How are they classified?

1. Explain the biological roles and structural aspects of rubredoxins and feredoxins.

 

 

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