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Theoretical Study on the Aromaticity of Metallasilapentalynes

Theoretical Study on the Aromaticity of Metallasilapentalynes. Advisor: Jun Zhu Reporter: Xuerui Wang. Outline. Background . Computational Method. Results and Discussion. Conclusion . Background. 1979. 1982. Thorn ,D , L.; Hoffman, R. Nouv . J. Chim . 1979 , 3 , 39 . 2001.

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Theoretical Study on the Aromaticity of Metallasilapentalynes

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  1. Theoretical Study on the Aromaticity of Metallasilapentalynes Advisor: Jun Zhu Reporter: Xuerui Wang

  2. Outline Background Computational Method Results and Discussion Conclusion

  3. Background 1979 • 1982 Thorn ,D , L.; Hoffman, R. Nouv . J. Chim.1979, 3, 39. 2001 G.P. Elliott, W.R. Roper, J. M. Waters, J. Chem. Soc. Chem.Commun, 1982, 811 TingbinWen, GuochenJia, Angew. Chem. Int. Ed, 2001, 40, 1951

  4. antiaromaticity 8e distorted triple bond extremely strained 116 destabilization Introduce a metal into the ring aromaticity 10e reduce the ring strain significantly 129.5 X-ray molecular structure

  5. The aromaticity of osmapentalyne Planar eight-membered metallabicycle C-C bond lengths 1.377-1.402Ǻ Benzene 1.396Ǻ This feature suggests an aromatic πconjugation result from resonance structure Down-field H chemical shifts silicon atom is reluctant to participate in  bonding C NMR a lower field than osmabenzynes Kutzelnigg, W. Angew. Chem., Int. Ed. Engl.1984, 23, 272.

  6. Why Mδ--Siδ+ σ-donation/weak π-back donation Fischer carbene，M→Lis limited. Frederick, P.; Arnold, J. Organometallics 1999, 18, 4800.

  7. show high reactivities toward nucleophiles Okazaki, M.; Tobita, H.; Ogino, H. Dalton Trans. 2003, 493.

  8. Computational Method DFT Package : Gaussian 03 Method: B3LYP basis sets : 6-311++G ** LanL2DZ: Ru(ζ(f) = 1.235), Os(ζ(f) = 0.886) ,P(ζ(d) = 0.340), Cl(ζ(d) = 0.514), Si(ζ(d) = 0.262). 1. Ehlers, A. W.; Böhme, M.; Dapprich, S.; Gobbi, A.; Höllwarth, A.; Jonas, V.; Köhler, K. F.; Stegmann, R.; Veldkamp, A.; G., F. Chemical Physics Letters, 1993, 208, 111. 2. Check, C. E.; Faust, T. O.; Bailey, J. M.; Wright, B. J. J. Phys. Chem. A 2001, 105, 8111.

  9. Results and Discussion Stability comparison which silicon in different positions of the ring (kcal/mol)

  10. HOMO (-5.67ev) HOMO-1(-5.90ev) HOMO-2 (-6.14ev) HOMO-3 (-6.96ev) HOMO-8(-8.63ev) HOMO-12(-9.96ev) Figure 1.optimized structure of osmasilapentalyne and the occupied  MOs together with their energies

  11. HOMO-1(-6.01ev) HOMO(-5.82ev) HOMO-3(-7.10ev) HOMO-2(-6.24ev) HOMO-8(-8.58ev) HOMO-12(-9.98ev) Figure 2.optimized structure of ruthenasilapentalyne and the occupied  MOs together with their energies

  12. the nucleus-independent chemical shift (NICS) values for each ring by DFT calculations 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 A B Ring A; NICS(0) = - 5.0 NICS(1) = - 7.6 NICS(2) = - 5.2 NICS(-1) = - 7.7 NICS(-2) = -5.3 NICS(1)zz = -15.3 Ring B: NICS(0) = - 7.5 NICS(1) = - 7.7 NICS(2) = - 3.7 NICS(-1) = -7.8 NICS(-2) = -3.7 NICS(1)zz = -13.4 Figure 3. the NICS values of the each ring

  13. Isomerization stabilization energies (kcal/mol) of metallasilapentalyne compare to metallapentalyne Figure 4.Isomerization stabilization energies (kcal/mol) of metallasilapentalyne compare to metallapentalyne.

  14. Figure 5.the transition of the osmasilapentalyne and (Si)-Cl -osmasilapentalene

  15. Conclusion From the view of π molecular orbitals and negative NICS values compared to benzene both reveal aromaticity in osmasilapentalyne and ruthenasilapentalyne. And the large negative ISEs can also indicate aromaticity. From the view of thermodynamics, the Cl atom has the possiblity to migrate, but from the figure 5 we can see there are high energy barrier to climb, so from the dynamics, the migration may be difficult.

  16. Thank you

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