Theoretical Study on the silaaromatics

1. Theoretical Study on the silaaromatics Speaker: Xuerui Wang Advisor : Jun Zhu Dec. 23. 2013

2. Outline [1,3]- substituent Shift for the Formation of the Silabenzenes 1 1 2 The aromaticity of metallasilapentalynes 3 3 Summary and Future work

3. Background driving force Aromaticity silicon atom is reluctant to participate in  bonding Kutzelnigg, W. Angew. Chem., Int. Ed. Engl. 1984, 23, 272.

4. Results and Discussion silicon atom is reluctant to participate in  bonding sp3 Bent’s rule : atomic s character tends to concentrate in orbitals that are directed toward electropositive groups and atomic p character tends to concentrate in orbitals that are directed toward electronegative groups. (a) Bent, H. A. Chem. Rec.1961,61, 275. (b) Zhu, J.; Lin, Z.; Marder, T. B. Inorg.Chem.2005, 44, 9384.

5. Results and Discussion Evaluate Aromaticity : ISE(isomerization stabilization energy) method and NICS( nucleus independent chemical shift) calculations NICS(0)zz -11.2 (X = H) -11.6 (X=NMe2) Figure 3. [1,3]-substituent shift for the formation of silabenzenes with various substituents.

6. Results and Discussion Figure 4.Plot of reaction free energies (ΔG) against the percentage of the s character of Si in the Si-X bonds.

7. Results and Discussion Figure 5. The plot of s character of Si to the Si-X σ bond vs reaction barriers (ΔG)

8. Results and Discussion Figure 6. Plot of reaction free energies (ΔG) against the percentage of the s character of Si in the Si-X bonds by replacing the acyl group with methylene group in acylsilane..

9. Results and Discussion Figure 7. Plot of reaction free energies (ΔG) against the percentage of the s character of Si in the Si-X bonds in nonaromatic system.

10. Results and Discussion Figure 8. Plot of reaction free energies (ΔG) against the percentage of the s character of Si in the Si-X bonds in the osmasilabenznes.

11. Summary 1. The contribution from aromaticity can be evaluated quantitatively (ca. 30 kcal/mol) in such rearrangement. 2. Bent's rule plays an important role in both the thermodynamics and kinetics of the rearrangement . 3. Our findings could be a useful guide to the synthesis of silabenzenes.

12. Outline [1,3]- substituent Shift for the Formation of the Silabenzenes 1 1 2 The aromaticity of metallasilapentalynes 3 3 Future work

13. Background 8e 10e Introduce a metal silicon atom is reluctant to participate in  bonding 116 ° 129.5 ° distorted triple bond extremely strained reduce the ring strain significantly Kutzelnigg, W. Angew. Chem., Int. Ed. Engl. 1984, 23, 272. Zhu, C.; Li, S.; Luo, M.; Zhou, X.; Niu, Y.; Lin, M.; Zhu, J.; Cao, Z.; Lu, X.; Wen, T.; Xie, Z.; Schleyer, P. v. R.; Xia, H. Nat. Chem. 2013, 5, 698.

14. Results and Discussion The aromaticity of metallasilapentalynes Ring A; NICS(0) = - 7.3 NICS(1) = - 9.8 NICS(2) = - 5.9 NICS(-1) = - 10.0 NICS(-2) = - 6.2 NICS(1)zz = - 19.8 Ring B: NICS(0) = - 8.9 NICS(1) = - 8.8 NICS(2) = - 4.1 NICS(-1) = - 9.1 NICS(-2) = - 4.2 NICS(1)zz = - 16.2 Figure 9. The optimized structure 、the ISEs values of the osmasilapentalynes and the NICS values of the each ring

15. The effect of ligand The effect of base The ring strain

16. Summary • From the view of negative ISEs and negative NICS values compared to benzene both reveal aromaticity in osmasilapentalyne. • osmasilapentalyne prefer -donor ligands than -accepter ligands.

17. Outline [1,3]- substituent Shift for the Formation of the Silabenzenes 1 2 The aromaticity of metallasilapentalynes 3 3 Future work

18. Future work 1. Theoretical study on the [1,3]- substituent shift for the formation of the stannumbenzenes and germaniumbenzene. 2. Tune the metal center by other transition metals.

19. Organophosphorus compounds pesticide medicine antibacterial agents enzyme inhibitors flame retardant anti HIV agents 19

20. Condition Optimization ？

21. 致谢 感谢朱军老师在学习、生活等各方面给予的关心与指导! 感谢赵玉芬老师、特别要感谢唐果老师、高玉珍师姐、许健师兄、张鹏波、吴巨在实验上的悉心指导和帮助! 感谢实验室的范景兰师姐、黄莹师姐以及其他同学的热心帮助！

22. Thank you for your attention！