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Created by Margaret L. Scheuermann, Princeton University; Abby R. O’Connor, The College of New Jersey,
[email protected]. Copyright Scheuermann and O’Connor, 2014. This work is licensed under the Creative
Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. To view a copy of this license visit
http://creativecommons.org/about/license/
Literature Discussion Learning Object:
Generation and Structural Characterization of A Gold(III) Alkene Complex
Langseth, E.; Scheuermann, M. L.; Balcells, D. Kaminsky, W. Goldberg, K. I.; Eisenstein, O.; Heyn, R. H.; Tilset,
M. Angew. Chem. Int. Ed. 2013, 52, 1660-1663.
DOI: 10.1002/anie.201209140
1. Why are gold complexes worthwhile to investigate? You may need to use other sources to support your response.
2. Why has it been challenging to isolate Au+3 complexes containing -bound ligands? Consider the interactions
involved in the metal-ligand bond.
3. Determine the formal oxidation state, dn configuration, and electron count for complexes 1-3.
4. Has the formal oxidation state of Au changed? Would you expect to see a change in oxidation state? What type of
reaction occurred?
5. The yield of (cod)AuMe2+OTf – is highest when two equivalents of triflic acid are used. Why? What is the role of
each equivalent of triflic acid in the reaction?
6. In most cases the δ values of vinylic protons become smaller upon binding to a metal center. What phenomenon
causes this? In contrast, the vinylic protons in 3 are shifted to higher δ values relative to free cod. How do the
authors explain this?
Created by Margaret L. Scheuermann, Princeton University; Abby R. O’Connor, The College of New Jersey,
[email protected]. Copyright Scheuermann and O’Connor, 2014. This work is licensed under the Creative
Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. To view a copy of this license visit
http://creativecommons.org/about/license/
7. In Figure 1 (reproduced below with permission, © 2013 Wiley VCH) the hydrogen atoms were “omitted for
clarity”. Draw the hydrogen atoms on C3, C4, C7, and C8 using dashes and wedges to indicate their positions.
8. How do the C=C bond lengths in metal-bound cyclooctadiene compare with those in free cyclooctadiene? What
does this suggest about the bond order for the C=C bonds in cyclooctadiene when it coordinates to a metal center?
9. Briefly outline the differences in geometry between free cyclooctadiene and metal-bound cyclooctadiene.
10. How do the backbonding interactions compare in (cod)AuMe 2+ and (cod)PtMe2? Why is the backbonding
lessened in the Au complex?
11. Density functional theory (DFT) calculations can determine the probable electron distribution around a
molecule. Chemists use molecular orbitals to describe the electron distribution that is calculated. Figure 2 shows
pictures of the molecular orbitals associated with the backbonding interaction. Which d orbitals on the Pt/Au centers
contribute to the molecular orbital associated with the backbonding interaction?
12. At which complex (Au or Pt) do these d orbitals contribute most strongly to the molecular orbitals associated
with the backbonding interactions?
13. To prepare for the class discussion about π-bound ligands please draw the HOMO and LUMO for ethylene.
Remember to draw the hydrogen atoms.