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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)
- The thermodynamic stability of high-spin complexes of d0,5,10 metal ions are lower than that of other dn metal ions under identical ligand framework. Comment upon this observation.
- It is exceedingly difficult to synthesize low-spin Td complexes of first row transition metals. Rationalize.
- 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.
- How are the s– and p-bonding quantified by AOM?
- The CN stretching vibration in cyano complexes occur at higher energy than that of free cyanide ion. Explain.
- Differentiate trans-effect and trans-influence.
- What is p-acceptor series? How is it constructed?
- Transition metal complexes are invariably colored, while their cabonyls are mostly colorless. Offer a reasonable explanation.
- What is organometallation reaction? Cite an example.
- 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)
- Give an account of isomerism in coordination compounds. How is fluxional isomerism studied experimentally?
- d6 Metal ions have a strong tendency to form Oh 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.
- How are the following differentiated by IR spectroscopy: (a) nitro- and nitrito complexes and (b) bridging- and terminal carbonyls?
- State Jahn Teller theorem. Explain static dynamic Jahn Teller effect with an example. How is this studied experimentally?
- What are Orgel diagrams? Construct the Orgel diagram for d3,8 metal ions in Oh and Td geometries.
- Give an account of the synthesis and structural features of organometallic complexes of cyclobutadiene and cycloheptatriene.
- 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.
- Give an account of the mechanism of substitution reactions in octahedral complexes.
- a. What are 16- and 18-electron complexes? Cite an example each.
- Explain the bonding and structural aspects of transition metal complexes of two open chain p-donor organic ligands.
- Give a brief account of photoisomerization and photosubstitution reactions of coordination compounds with examples.
- Explain the mechanism of hydroformylation reaction.
- Explain the structure and functions of superoxide dismutase.
Part – C
Answer FOUR questions. Each question carries TEN marks (4 x 10 = 40 marks)
- a) With the help of MO theory show that s-donation and p-back bonding increase the magnitude of 10Dq values. (6)
- b) Explain the electronic spectral features of high spin Oh and Td complexes of d1-9 metal ions. (4)
- Explain the principles of angular overlap model. Show that Dt = 4/9 Do with the help of this theory.
- a) Explain the mechanism of Smidt reaction highlighting the sequence of reactions. (5)
- b) Give a brief account of the synthesis of Ziegler-Natta catalysts. Explain the mechanism of
polymerization of olefins by one such catalyst. (5)
- a) What are electron transfer reactions? Differentiate complimentary and noncomplimentary electron
transfer reactions with examples. (3)
- 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)
- a) What is supramolecular chemistry? Mention the various supramolecular interactions. (3)
- Explain the formation of supramolecular assemblies formed by the recognition of neutral molecules and anions by molecular receptors. (7)
- a) Explain the structural features of hemoglobin and myoglobin. Explain the mechanism of oxygen
transport and storage by these heme proteins. (6)
- b) Explain the structural features and the biological roles of the enzyme, carboxypeptidase A.
(4)
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