(2 pts.) 1. What is meant by the term hexadentate ligand?

(12 pts.) 3. Give the formula for the coordination species shown (use [ ] to indicate coordination sphere):

(2 pts.) 4. Why are low-spin complexes usually not encountered for tetrahedral coordination?

The following questions are from the reading assignment: "The Iron Sandwich. A Recollection of the First Four Months" by Geoffrey Wilkinson.

(2 pts.) 5. What was the relationship of Al Cotton (Prof. F. A. Cotton Texas A&M) to Wilkinson as described in this article?

(2 pts.) 6. What was Sidgwick's description of the cyclopentadienyl ion in his book, "The Chemical Elements and their Compounds?

(2 pts.) 7. The second sandwich compound made (the first one made by Wilkinson) was?

(2 pts.) 8. What experimental measurements did Al Cotton contribute to the study?

The following questions are from the reading assignment: "Fluxionality in Organometallics and Metal Carbonyls" by F. A. Cotton.

(2 pts.) 9. What is meant by the term Fluxionality?

(6 pts.) 10. What were the three (3) possible explanations suggested by Cotton for why Fe(CO)₅ gave only a single line in the C-13 NMR spectrum?

(4 pts.) 11. What were the predicted rations of the C-13 NMR singles for the proposed trigonal bipyramidal and square pyramidal structures?

(3 pts.) 12. Room temperature C-13 NMR spectra of (h ⁵-C₅H₅)(h ¹-C₅H₅)Fe(CO)₂ showed one line. What did the -60^oC spectra show? Why did this indicate that a lower temperature was necessary?

(2 pts.) 13. The cis- and trans- forms of (h ⁵-C₅H₅)₂Fe₂(CO)₄, structures IV and V page 37, interconvert rapidly on the NMR time scale as observed in their H-1 spectra. By what mechanism odes this interconversion occur?

(2 pts.) 14. What type of acid-base chemistry is involved in coordination chemistry?

(2 pts.) 15. Describe Werner’s two levels of valence.

(3 pts.) 16. Calculate the effective atomic number (EAN) of the Ru⁺² ion in [Ru(NH₃)₄(HSO₃)₂] (assume that all the ligands are monodentate).

(4 pts.) 17. Explain why d⁴, d⁵, d⁶, and d⁷ all show both low spin and high spin cases.

Octahedral Field

(2 pts.) 18. What is the splitting pattern of the d-orbitals in an octahedral field?

(2 pts.) 19. Which orbitals (be specific) are found in the upper group in octahedral field?

(2 pts.) 20. For the valence bond model, what hybridization is found in an octahedral field?

Coordination Chemistry

(2 pts.) 21. Give examples of coordination isomers.

(2 pts.) 22. Give examples of geometric isomers.

(2 pts.) 23. Where does the term coordination come from in coordination chemistry?

For the [CoCl₆]^4- ion,

(2 pts.) 24. How many unpaired electrons on the Co⁺² ion?

(2 pts.) 25. What is the ligand field stabilization energy for this ion?

(4 pts.) 26. Draw the chain theory structure (Jorgensen) and the coordination theory structure (Werner) for CoCl₃*5NH₃ that would precipitate 2formula units of AgCl for each formula unit of cobalt compound when treated with excess Ag¹⁺ ion.

(2 pts.) 27. What is the Jahn-Teller effect?

(2 pts.) 28. What causes the Jahn-Teller effect?

(2 pts.) 29. Does the Jahn-Teller effect stabilize or destablize the resulting coordination species?

(3 pts.) 30. Calucalte the effective atomic number of [Ru(bipy)₃]⁺², bipy refers to 2,2'bipyridine, a bidentate ligand.

(4 pts.) 31. What was the final piece of evidence that Werner provided that convinced the scientific community that the coordination theory was the corrrect interpretation of the data?

(3 pts.) 32. For a d² case, what is the value, in Dq units, for the transition from T_1g à T_2g?

I neither received nor gave any assistance on this examination nor did I see anyone else give or receive assistance on this examination.

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