Transition Metal Cations - Inorganic Chemistry - Exam, Exams for Inorganic Chemistry. Aliah University
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Transition Metal Cations - Inorganic Chemistry - Exam, Exams for Inorganic Chemistry. Aliah University

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Transition Metal Cations, Crystal Field Splitting Patterns, Reaction Mechanism, Reaction Profile, Associative Mechanism, Intermediates and Transition, Volume of Activation, Entropy of Activation, Volume of Activation, Re...
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Autumn Examinations 2009/ 2010 Exam Code(s) 3BS9, 1OA1Exam(s) Third Science Module Code(s) CH307 Module(s) Inorganic Chemistry Paper No. Repeat Paper External Examiner(s) Professor K. Molloy Internal Examiner(s) Professor P. McArdle,

and Drs. A. Erxleben, T. Higgins and L. Jones Instructions: Answer 1 question from each of sections A to D.

All questions are worth 25 marks.

Duration 2 Hours

No. of Pages 5 School Chemistry Course Co-ordinator(s) Professor P. McArdle Requirements: Handout Statistical/ Log Tables Cambridge Tables Graph Paper Log Graph Paper Other Materials

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Section A

1. Answer each of the following (a) Describe the crystal field splitting patterns for (i) octahedral, (ii) tetrahedral, and

(iii) square planar, geometries. [6 marks]

(b) Explain the term ‘Octahedral Site Stabilization Energy’ (OSSE), and determine

the OSSE (in terms of 10Dq) for the following transition metal cations; Fe(II),

Fe(III), Ni(II) [7 marks]

(c) Identify the range of factors that influence whether a transition metal

coordination compound will exhibit octahedral or tetrahedral geometry.

[6 marks]

(d) Give three examples of transition metal coordination compounds that you

predict will exhibit tetrahedral geometry and explain the rational for your

choice. [6 marks]

2. Answer each of the following. (a) Draw molecular orbital bonding schemes for the octahedral molecules,

[Fe(NH3)6]2+ and [Fe(CN)6]3-.. [8 marks]

(b) Draw crystal filed splitting patterns for the octahedral molecules, [Fe(NH3)6]2+

and [Fe(CN)6]3-, and compare the molecular orbital and crystal field approaches

to bonding in these molecules [8 marks]

(c) Explain the order of π-donor, π-acceptor and σ-donor ligands in the

spectrochemical series. [9 marks]

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Section B 3. Answer each of the following. (a) Describe the roles played by potassium, calcium and zinc in biological systems.

[6 marks]

(b) Describe the alpha helix and beta-sheet structure in proteins and identify the

amino acid side chains that coordinate to metal ions. [10 marks]

(c) Describe the biological roles of iron. Give examples of some proteins that

contain iron. Describe the function and sketch the active centre for one iron

containing protein. [9 marks]

4. Answer each of the following; (a) Draw the structures of the reaction products of the following reactions:

(i) [PtCl3(CO)] - + NH3

(ii) [PtI4]2- + 2 NH3 [4 marks] (b) The reaction

[PtCl(NH3)3]+ + H2O  [Pt(H2O)(NH3)3]2+ + Cl- proceeds via an associative mechanism.

(i) Sketch the reaction mechanism. (ii) Sketch the reaction profile. Clearly indicate intermediates and transition

states. (iii)What sign is expected for the volume of activation? [8 marks]

(c) Suggest an experiment to measure (i) the entropy of activation (ii) the volume of activation for a reaction. [5 marks] (d) When [CoCl(NH3)5]2+ and [Cr(H2O)6]2+ are mixed, a redox reaction takes

place and the products [Co(H2O)6]2+, NH4+ and [CrCl(H2O)5]2+ are formed. Sketch the reaction mechanism. [8 marks]

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Section C 5. Answer each of the following;(a) Assign names to each of the following Boranes: (i) [B6H6]2- (ii) [B5H9] (iii) [B4H10] (iv) [B5H8]- [8 Marks] (b) Using Wade`s rules, determine the structures of (i)-(iv) above. [12 Marks] (c) Suggest one method for the synthesis of the carborane closo-[C2B4H6] and draw

its two possible structural isomers. [5 Marks] 6. Answer each of the following. (a) Suggest products for each of the following: V + excess F2 = V + excess Cl2 = V + excess Br2 = V + excess I2 = [NH4][VO3] + heat = [5x3 marks] (b) Describe the formulae and stability of the anhydrous halides of chromium.

[10 marks]

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Section D

7. Answer each of the following; (a) Describe the 18 electron rule as it applies to transition metal complexes and

give an example of a complex to which the rule applies. [4 marks] (b) Briefly outline the difference between Schrock and Fischer type carbene

complexes. [5 marks] (c) Explain the terms oxidative addition and reductive elimination. Use the

addition of MeI to Vaska’s complex to illustrate oxidative addition. . [8 marks] (d) Explain why there are no stable neutral binary metal carbonyls for titanium or

vanadium. [8 marks] 8. Answer each of the following; (a) Write each of the following in the [MLaXb]c+ formalism and give the metal

valence electron count. (i) [Ni(5-C5H5)(CO)Br] (ii) [Mn(6-C6H6)(CO)2PPh2] (iii) [Fe(CO)3(PPh3) 2I2] (iv) [Fe(2-buta-1-ene)(CO)3Br] (v) [W(3-allyl)3PPh3I]. [15 marks] (b) Describe a bonding scheme suitable for the bonding in M(CO)x transition

metal complexes. [10 marks]

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