PG – 701

*PG701*

II Semester M.Sc. Degree Examination, July/August 2013 (NS) (2010-11 & Onwards) CHEMISTRY C. 201 : Inorganic Chemistry – II (Coordination Chemistry) Time : 3 Hours

Max. Marks : 80

Instruction : Answer question No. 1 and any five of the remaining. 1. Answer any ten of the following :

(10×2=20)

a) Explain the factors responsible for the steady decrease in the stepwise stability constant of a reaction M + n[L] MLn. b) Strong donor solvents decrease the stability constants. Substantiate with an example. c) Predict the geometrics of metal complexes whose coordination number are 5 and 6. d) Point out the shortcomings of crystal field theory. e) Distinguish the bonding between M – H and M – H2 complexes. f) Explain the fact that NO is capable of ferming both linear and angular M – NO groups in terminal metal nitrosyl complexes. g) Mo(CO)3(PF3)3 exhibits γ CO at 2090 and 2055 cm–1 whereas Mo(CO)3(C2H5)3 exhibits at 1937 and 1841 cm–1. Explain. h) What is cotton effect ? Explain with an example. i) Explain the terms, term symbol and microstate of a configuration. j) How is nephelauxetic ratio related to Racah parameter ? Give its importance. k) Calculate the magnetic moment values of the following complexes using spin only formula. [Co(NH3)6]Cl3 and K3[Fe(C2O4)3].3H2O. l) Distinguish between ferro and anti ferro magnetism. P.T.O.

PG – 701

-2-

*PG701*

2. a) Discuss the factors affecting the stability of metal complexes with respect to nature of metal ion and ligand. b) Explain the determination of stability constant of metal complexes by spectrophotometric method. c) Obtain the relationship between stepwise and overall stability constant of a complex. (5+4+3=12) 3. a) Giving examples comment on the factors influencing the magnitude of 10 Dq in octahedral metal complexes. b) Based on group theoretical approach set up the Mo energy level diagram for [Co(NH3)6]3+ ion. Illustrate the modification of the diagram when all the NH3 molecules are replaced by chloride ligands. c) Obtain the CFSE of [Cr(OH2)6]2+ ion whose crystal field splitting and pairing energies are 13,900 and 23,500 cm–1, respectively. (4+5+3=12) 4. a) Discuss the different bonding modes of isocyanide and dioxygen in metal complexes. b) What is CD ? Explain its utility in determining the absolute configuration of metal complexes. c) Describe the technique for studying stereochemical non-rigidity. (4+4+4=12) 5. a) Discuss the structure and bonding of metal phosphine complexes. b) Obtain the spectroscopic ground terms for trivalent vanadium and iron ions. c) Write a note on selection rules pertaining to electronic spectra of metal complexes. (4+4+4=12) 6. a) What are Tanabe-Sugano diagrams ? Explain their advantages as compared to Orgel diagrams. b) The electronic absorption spectrum of [Cr(OH2)6]3+ displays bands at 17,400, 24,500 and 37,500 cm–1. Draw the appropriate Orgel diagram and assign the bands to different transitions. Calculate Dq, B1, Q and X(B of Cr3+ = 918 cm–1). c) Explain the significance of Racah parameter. (5+4+3=12) 7. a) Explain the effect of temperature on the susceptibility of different magnetic materials. b) Describe the measurement of magnetic susceptibility using Gouy balance. c) Discuss the effect of spin-orbit coupling on the magnetic properties of complexes. (4+4+4=12) ______________________