Presentation on theme: "Advisor: Jun Zhu Speaker: Xuerui Wang Theoretical study on the interconversion of silabenzenes and their non-aromatic isomers via the [1,3]-substituent."— Presentation transcript:
Advisor: Jun Zhu Speaker: Xuerui Wang Theoretical study on the interconversion of silabenzenes and their non-aromatic isomers via the [1,3]-substituent shift: aromaticity vs Bent's rule
Background Rouf, A. M.; Jahn, B. O.; Ottosson, H. Organometallics.2013, 32, 16 driving force Aromaticity Kutzelnigg, W. Angew. Chem., Int. Ed. Engl. 1984, 23, 272. silicon atom is reluctant to participate in bonding
Computational Method Package : Method : basis sets : Gaussian 09 M06-2X / B3LYP 6-311+G ** 1.(a) Becke, A. D. J. Chem. Phys. 1993, 98, 5648. (b) Miehlich, B.; Savin, A.; Stoll, H.; Preuss, H. Chem. Phys. Lett. 1989, 157, 200. (c) Lee, C.; Yang, W.; Parr, G. Phys. ReV. B 1988, 37, 785. 2. Zhao,Y.; Truhlar, D. G. Theor. Chem. Acc. 2008, 120, 215. 3. Frisch, M. J. et al. Gaussian, Inc., Wallingford CT, 2010. DFT
Results and Discussion Figure 4. The formation of silabenzenes through the [1,3]-Si→O substituent shift. 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. reluctancesp 3
Results and Discussion Figure 6. [1,3]-substituent shift for the formation of silabenzenes with various substituents. Figure 5. The calculated ISE values of A1' and A2'. NICS(0)zz -11.2 (X = H) -11.6 (X=NMe2) Evaluate Aromaticity : ISE(isomerization stabilization energy) method and NICS( nucleus independent chemical shift) calculations
Results and Discussion Figure 7. The plot of s character of Si to the Si-X σ bond vs ΔG
Results and Discussion Figure 8. The plot of s character of Si to the Si-X σ bond vs reaction barriers (ΔG )
Results and Discussion Figure 9. 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..
Conclusion 1. Aromaticity is not the only driving force for the reaction. 2. Bent‘s rule plays an important role in formation of the silabenzene. 3. Our findings could be a useful guide to the synthesis of silabenzenes.