LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

GH 39

M.Sc. DEGREE EXAMINATION – CHEMISTRY

THIRD SEMESTER – APRIL 2008

    CH 3809 – COORDINATION CHEMISTRY

 

 

 

Date : 29/04/2008            Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

PART – A

Answer all the questions                                                            (10 ´ 2 = 20)

 

1. Why do octahedral complexes undergo substitution of ligands by S_N1mechanism?
2. What are the merits and demerits of CFT?
3. Define CFSE. Calculate CFSE for d⁷ , low spin and high spin octahedral system.
4. What is spectrochemical series? Mention any two applications.
5. Derive the ground term configuration of d³?
6. Why Mn(II), d⁵ metal complexes are colourless?
7. Mention two biologically important coordination compounds and their applications.
8. Find the values of x and y assuming the validity of the 18 electron rule for [Mn(CO)_x(NO)_y].
9. Why is the rate of electron transfer reaction slow in the system [Co(NH₃)₆]²⁺/³⁺ compared to [Fe(CN)₆]^3-/^4- system?
10. What is Wilkinson catalyst? What type of chemical reaction can be effected by using this catalyst?

 

PART – B

Answer any EIGHT questions                                                      (8 ´ 5 = 40)

 

1. Calculate OSSE and state whether the following oxides are spinel or inverse spinel : Mn₃O₄, Fe₃O₄, CuFe₂O₄.
2. Differentiate labile and inert complexes using crystal field theory.
3. Discuss any two evidences of crystal field theory’
4. What is linkage isomerism? How are these isomers differentiated by IR spectral analysis?
5. Write short notes on Nephelauxetic effect.
6. State and explain Jahn-Teller effect.
7. Why do electronic spectra of [V(H₂O)₆]3⁺ show only two absorption bands against three predicted for the system?
8. What is trans effect? Explain the theories of trans effect in explaining the mechanism of substitution reaction of square planar complexes.
9. Discuss the expected Esr spectrum of  [Cu(salicylaldimine)₂]²⁺ ion.
10. What are supramolecules? Explain the nature and types of interactions of supramolecule.
11. Discuss the structure and functions of the enzyme, carboxypeptidases.
12. Explain the types of photochemical reactions with examples.

PART C

Answer any FOUR questions                                                (4 x 10 = 40)

 

1. How do the d-orbitals split in square planar and tetrahedral crystal field of ligands?
2. Explain with the help of MO theory why Cl^– acts as a weak ligand where as CN^– acts as a strong ligand in octahedral transition metal complexes.
3. Draw and explain the Orgel diagram for d², d⁷ octahedral and d⁸, d³ tetrahedral configuration of metal ion and explain the possible electronic transitions.
4. Explain the mechanism and factors affecting the innersphere and outersphere electron transfer reaction of metal complexes.
5. Write notes on i) the Wackers process ii) hydroformylation reaction
   iii) metathesis reaction.

28. Explain the structural aspects of haemoglobin in the oxygen transport.

 

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DB 26

LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

THIRD SEMESTER – November 2008

    CH 3809 – COORDINATION CHEMISTRY

 

 

 

Date : 05-11-08                 Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

Part – A

 

Answer ALL questions. Each question carries TWO marks                                       (10 x 2 = 20 marks)

 

1. The thermodynamic stability of high-spin complexes of d^0,5,10 metal ions are lower than that of other dⁿ metal ions under identical ligand framework. Comment upon this observation.
2. It is exceedingly difficult to synthesize low-spin T_d complexes of first row transition metals. Rationalize.
3. Jahn-Teller distortion in 6-coordinate complexes of d¹ metal ions escapes experimental detection, whereas such a distortion can be detected in 6-coordinate complexes of d⁹ metal ions. Rationalize.
4. How are the s– and p-bonding quantified by AOM?
5. The CN stretching vibration in cyano complexes occur at higher energy than that of free cyanide ion. Explain.
6. Differentiate trans-effect and trans-influence.
7. What is p-acceptor series? How is it constructed?
8. Transition metal complexes are invariably colored, while their cabonyls are mostly colorless. Offer a reasonable explanation.
9. What is organometallation reaction? Cite an example.
10. What are synthetic oxygen carriers? Cite a few such model complexes.

 

Part – B

 

Answer EIGHT questions. Each question carries FIVE marks                                 (8 x 5 = 40 marks)

 

11. Give an account of isomerism in coordination compounds. How is fluxional isomerism studied experimentally?
12. d⁶ Metal ions have a strong tendency to form O_h complexes, while d⁸ metal ions have a strong tendency to form square planar complexes with strong ligands. Explain with the aid of qualitative crystal field splitting energy level diagrams.
13. How are the following differentiated by IR spectroscopy: (a) nitro- and nitrito complexes and (b) bridging- and terminal carbonyls?
14. State Jahn Teller theorem. Explain static dynamic Jahn Teller effect with an example. How is this studied experimentally?
15. What are Orgel diagrams? Construct the Orgel diagram for d3,8 metal ions in O_h  and T_d geometries.
16. Give an account of the synthesis and structural features of organometallic complexes of cyclobutadiene and cycloheptatriene.
17. The epr spectrum of [Cu(salen)] consists of four sets of eleven lines each. Interpret the spectrum and substantiate your result with the help of experimental evidences.
18. Give an account of the mechanism of substitution reactions in octahedral complexes.
19. a.             What are 16- and 18-electron complexes? Cite an example each.
20.   Explain the bonding and structural aspects of transition metal complexes of two open chain          p-donor organic ligands.
21. Give a brief account of photoisomerization and photosubstitution reactions of coordination compounds with examples.
22. Explain the mechanism of hydroformylation reaction.
23. Explain the structure and functions of superoxide dismutase.

 

Part – C

 

Answer FOUR questions. Each question carries TEN marks                                   (4 x 10 = 40 marks)

 

23. a) With the help of MO theory show that s-donation and p-back bonding increase the magnitude of   10D_q values.                                                                                                                       (6)
24.    b)  Explain the electronic spectral features of high spin O_h and T_d complexes of d^1-9 metal ions.     (4)

 

24.    Explain the principles of angular overlap model. Show that D_t = 4/9 D_o with the help of this theory.

 

25. a) Explain the mechanism of Smidt reaction highlighting the sequence of reactions.                       (5)
26. b)  Give a brief account of the synthesis of Ziegler-Natta catalysts. Explain the mechanism of

polymerization of olefins by one such catalyst.                                                                             (5)

 

26. a) What are electron transfer reactions? Differentiate complimentary and noncomplimentary electron

transfer reactions with examples.                                                                                                   (3)

1. Explain the inner- and outer-sphere mechanisms of electron transfer reactions in coordination compounds with examples. Mention the various factors which affect these mechanisms.        (7)

 

27. a) What is supramolecular chemistry? Mention the various  supramolecular interactions.               (3)
28. Explain the formation of supramolecular assemblies formed by the recognition of neutral molecules and anions by molecular receptors.                                                                           (7)
29. a) Explain the structural features of hemoglobin and myoglobin. Explain the mechanism of oxygen

transport and storage by these heme proteins.                                                                               (6)

1. b)  Explain the structural features and the biological roles of the enzyme, carboxypeptidase A.

(4)

 

 

 

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