1. Speaker: ke An Advisor: Jun Zhu 2012.11.30 A Direct Energetic Measure of Aromaticity Based on a Cleavage of the Rings in Cyclic Compounds

2. Abstract Homodesmotic reaction 1 cyclicacyclic ASE 1. Hehre, W. J.; Ditchfield, R.; Radom, L.; Pople, J. A. J. Am. Chem. Soc. 1970, 92, 4796–4801.

3. Outline  Introduction  Results and discussion  Conclusion  Other work

4. Introduction Various criteria: Geometry 2 Energy 3,4 Magnetism 5 Electronic property 2. Krygowski, T. M.; Cyranski, M. K. Chem. Rev. 2001, 101, 1385-1419. 3. Slayden, S. W.; Liebman, J. F. Chem. Rev. 2001, 101, 1541-1566. 4. Cyranski, M. K. Chem. Rev. 2005, 105, 3773-3811. 5. Chen, Z.; Wannere, C. S.; Corminboeuf, C.; Puchta, R.. Schleyer, P. v. R. Chem. Rev. 2005, 105, 3842-3888.

5. Results and Discussion Benzene, naphthalene and pyridine were calculated at B3LYP/6-311+G* level, zero-point energy were applied. 6.Cyranski, M. K. Chem. Rev. 2005, 105, 3773–3811.

6. 7.Krygowski, T. M.; Cyranski, M. K. Chem. Rev. 2001, 101, 1385-1419. Pyrrole, furan and thiophene were calculated at MP2(fc)/6-311+G** level, zero-point energy were applied.

7. Attention : ? There are two trans π-conjugated configurations in the latter naphthalene. cis trans -3.6kcal/mol

8. Conclusion : The results above indicate that the cleavage method could be an effective way to evaluate the aromaticity of the cyclic compounds, especially for some cyclic unstrained π- conjugated rings

9. To examine the scope of the method

10. When CO replaces chloride ligand, there is a change from nonplanarity to planarity in osmabenzene. The dihedral in the former osmabenzene is 23.9 degrees. So its aromaticity is weaker than the latter one.

11. Conclusion  We conclude that the new method, based on the energy difference between the cyclic compound and the acyclic one, is able to produce a reliable result to evaluate the ASEs for both organic aromatics and metallaaromatics. In addition, it could be also applied to strained molecules if the strain energy can be evaluated separately.

12. Other Work Antiaromatics: Nonaromatics:

13. This method can also be employed to evaluate the ASEs of antiaromatics. The ring strain energy(RSE) of the cyclobutadiene is taken into consideration.

14. However, it seems to be that the osmacyclopentadiene is aromatic. How could it happen?

15. Next Plans  To evaluate the ASEs of other strained molecules.  To extend this method to other organic aromatics and metallaaromatics.  To calculate the energies of the excited states both in aromatics and antiaromatics.