LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
M.Sc. DEGREE EXAMINATION – CHEMISTRY
THIRD SEMESTER – APRIL 2012
CH 3809 – COORDINATION CHEMISTRY
Date : 24-04-2012 Dept. No. Max. : 100 Marks
Time : 1:00 – 4:00
Part-A
Answer all questions. Each question carries two 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.
- Identify the number of isomers of [Co(en)2(SCN)2]+.
- It is exceedingly difficult to synthesize low-spin Td complexes of first row transition metals. Rationalize.
- What is nephelauxetic ratio? Mention its significance.
- Transition metal complexes are invariably colored, while their cabonyls are mostly colorless. Offer a reasonable explanation.
- Jahn-Teller distortion in 6-coordinate complexes of low-spin d4 metal ions escapes experimental detection, while it can be detected in 6-coordinate complexes of high-spin d4 metal ions. Explain.
- Differentiate trans-effect and trans-influence.
- Organometallic compounds are formed by transition metal ions in their low oxidation state. Comment.
- What is halometallation reaction? Cite an example.
- Mention the biological roles of the enzyme carboxy peptidase A.
Part-B
Answer eight questions. Each question carries five marks:
- How is nitro- and nitrito complexes differentiated by IR spectroscopy?
- State Jahn Teller theorem. Explain static dynamic Jahn Teller distortion with an example. How is it studied experimentally?
- What is molecular recognition? Give an account of recognition of neutral molecules by molecular receptors.
- Explain photoisomerization and photosubstitution reactions in transition metal complexes with examples.
- Give an account of the synthesis and structural features of p-complexes of cyclooctatetraene and cycloheptatriene with transition metals.
- Explain supramolecular assemblies formed by self assembly methods.
- Give an account of the mechanism of substitution reactions in tetrahedral complexes.
- What is trans-effect? You are provided with K2PtCl4 and ammonia. How do you synthesisecis– and trans-isomers of [PtCl2(NH3)2]?
- Explain the synthesis of Ziegler-Natta catalysts and the mechanism of polymerization of olefins by this catalyst.
- 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.
- Write a note on copper proteins.
- Explain the structural features and biological roles of superoxide dismutase.
Part-C
Answer four questions. Each question carries ten marks:
23a. Identify the metal orbitals and LGOs suitable for s– and p-bonding in Oh complexes of transition metal ions. Construct a qualitative MO energy level diagram for s-bonding. (6)
- Justify the position of CO in the spectrochemical series with the help of MO theory. (4)
- Explain the principles of angular overlap model. Show that Dt = 4/9Do with the help of this theory.
25a. Explain the electronic spectral features of high-spin Oh and Td complexes of d1-9 metal ions. (6)
- Construct the Orgel diagram for high-spin d3 and d7Oh and Td complexes. (4)
26a. Explain the mechanism of palladium chloride-catalyzed production of acetaldehyde. (4)
- Explain the mechanism of replacement of coordinated water by another ligand in octahedral complexes. (6)
27a. Explain the mechanism of oxygen transport in mammalian systems. (7)
- Give an account of synthetic oxygen carriers. (3)
28a. What are electron transfer reactions? Differentiate complimentary and non-complimentary 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)
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