LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
M.Sc. DEGREE EXAMINATION – CHEMISTRY
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FOURTH SEMESTER – APRIL 2006
CH 4953 – ADVANCED COORDINATION CHEMISTRY
(Also equivalent to CH 4950)
Date & Time : 25-04-2006/9.00-12.00 Dept. No. Max. : 100 Marks
Part-A
Answer all questions. Each question carries two marks
- Organometallic compounds of transition metals are invariably colorless. Give reason.
- Cl-occupies the lower end of the spectrochemical series, yet the Do value of [RuCl6]3- is comparable to that of [Ru(H2O)6]2+. Offer a reasonable explanation.
- How is low-spin and high-spin complexes of d5 metal ion differentiated by electronic spectroscopy?
- Mention the causes of tetragonal distortion in transition metal complexes. How is it inferred from epr spectroscopy?
- How is the covalent character in transition metal complexes quantified?
- What is the oxidation state and spin state of iron centers in Fe_S proteins?
- How is p-acceptor series constructed?
- What is zero field splitting? Mention its causes in transition metal complexes.
- How does angular overlap of metal and ligand aos alter the magnitude of es- and ep-parameters?
- Illustrate transmetallation reaction with an example.
Part-B
Answer eight questions. Each question carries five marks
- Explain the structural features and biological roles of Fe-S proteins.
12 What is crystal field splitting parameter Dt? How is it manifested when Dqxy > Dqz and Dqxy < Dqz?
- How is nitro- and nitrito complexes differentiated by IR spectroscopy?
14 Explain the features of Tanabe-Sugano diagrams. In these diagrams the lowest energy excited state for a high-spin metal ion in a given geometry becomes the ground state for the low-spin state. Explain.
15 What is nitrogen fixation. Explain its mechanism
16 What are coupled chemical reactions? How are they classified? How do you infer such a process from cyclic voltammetry?
- Explain the structural aspects and biological roles of cytochromes.
- Give an account of the structural features of biological electron transfer agents.
- What is chelation therapy? Mention the specific disease which is cured by this therapy.
20 Explain the principle of AC polarography. How is the reversibility of a redox couple evaluated by this technique?
- What are optically trasparent thin layer electrodes? Mention their importance.
- What is static dynamic Jahn Teller distortion? How is it studied by esr spectroscopy?
Part-C
Answer four questions. Each question carries ten marks
23a Explain the electronic spectral features of low-spin and high-spin Oh complexes of d6 metal ion. (4)
b Explain the electronic spectral features of tetragonally distorted Oh complex of low-spin d6 metal ion and the method of evaluating the crystal field parameters. (6)
24a. Derive Marcus-Hush equation to compute the rate constant of electron transfer reactions. (7)
- How do you differentiate inner- and outer-sphere electron transfer reactions? (3)
25a. Explain hyperfine and superhyperfine splittings. (3)
- The epr spectrum of a high spin Mn(II) complex, doped onto a diamagnetic host, consists of 30 epr lines when there is no hyperfine splitting by the ligand. Interpret the spectrum with the help of a qualitative hyperfine splitting diagram. (7)
26a. p-Donation by ligands lowers 10Dq values whereas p-back bonding increases 10Dq values and facilitates M-L bonding. Explain with the help of MO theory with qualitative MO energy level diagrams. (5)
- Account for the difference in the properties of metal carbonyls and complexes of nitrogen donor ligands in the light of MO theory. (5)
27a. Explain the principles of angular overlap model.
- Show that Dt = 4/9Do with the help of this model.
28a. Illustate coordination template effect with examples. (4)
- What are compartmental ligands? Explain the method of synthesizing dinuclear macrocyclic and macroacyclic compartmental ligands with illustrative examples.(6)
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