Isomerization from Silacyclopentadienyl Complexes to Rhodasilabenzenes , Possible or Not?

1. Isomerization from Silacyclopentadienyl Complexes to Rhodasilabenzenes, Possible or Not? Ying huang

3. Metallabenzene 1. What’s metallabenzene complexes? . [M] = MLn, MLn-1X or MLn-2X2 2.History In 1979 ,Thorn and Hoffmann predicted the three classes of stable metallabenzenes . D.L. Thorn, R. Hoffmann, Nouv. J. Chim,1979, 3, 39

4. the first metallabenzene W.R. Roper, J. Chem. Soc. Chem.Commun. 1982, 811 In 1982 Since then Various metallaaromatics have been reported.

5. Iridabenzene 3 1 M.M. Haley,Organometallics,2003, 22, 3279; M.M. Haley, Chem. Eur. J, 2005, 11,1191

6. Rhodabenzene No rhodabenzene has yet been isolated. only rhodabenzvalene was isolated at -30 ℃ in 2002. 48% M. M. Haley, Organometallics ,2002,21,4320

7. Reasons DFT calculations (diffuse functions for use with the SDD and SDB-cc-pVDZ basis set-RECP combinations are presented for the transition metals.) M. E.van der Boom,J.M. L. Martin, J. Am. Chem. Soc. 2004, 126, 11699

8. But simple neutral silaaromatic compounds are known to be highly reactive. Silabenzene Aromaticity HF(B3LYP/6-311G**) Si- C :1.771 Å ASE( aromatic stabilization energy) :70–85% (6-31G*) of that of benzene. Apeloig, Y., Karni, M. ,Wiley: NewYork,1998, 2, Chapter 1.

9. Reason Free energy surface (kcal/mol) in the reaction of silabenzene with acetylene. ( B3LYP/6-31G(d)) N.Tokitoh,J. Chin. Chem. Soc,2008,55, 3

10. 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl synthesis No silabenzene stable at ambient temperature has ever been reported until 1999. N . Tokitoh ,Pure Appl. Chem, 1999,71, 495.

11. X-ray Raman Schematic drawings of the vibrational modes for the strongest in-plane vibrations of benzene and silabenzene Molecular structure of Tbt-substituted silabenzene bond lengths (Å): Si-C=1.765(1.770) C-C =1.391(1.399;1.381;1.394) N.Tokiton,Acc. Chem. Res. 2004, 37, 86

12. Half-Sandwich complexes containing Si N.Tokitoh,Organometallics , 2005 , 24 , 6141

13. A. Sekiguchi ,J. Am. Chem. Soc,2009, 131, 9902 Rhodium Half-Sandwich The first group 9 metal complex with the heavy cyclopentadienylligand and the first heavy cyclopentadienyl complex of half-sandwich type. 47%

14. bond lengths (Å): Si1-Si2 =2.2294(8),Si2-Si3 = 2.2807(8), Si1-C2 =1.871(2), Si3-C1 = 1.857(2), C1-C2=1.413(3), Si1-Si4 =2.3864(8), Si2-Si5 =2.3821(8), Si3-Si6 =2.4001(8), Rh1-Si1 =2.5231(6), Rh1-Si2 =2.6845(6), Rh1-Si3 =2.4806(6), Rh1-C1 =2.371(2), Rh1-C2 = 2.323(2), Rh1-C34 =1.900(2), Rh1-C35 =1.873(2), C34-O1 =1.141(3), C35-O2 =1.147(3).

15. Zhenyang Lin , GuochenJia,Dalton Trans., 2011, 40, 11315 DFT Package : Gaussian 03 Method: B3LYP basis sets : 6-31G LanL2DZ (Re(z(f) = 0.869))

16. energies for the rearrangement reactions of rhenabenzenes. The relative electronic energies and Gibbs free energies at 298 K (in parentheses) are given in kcal mol-1.

17. possible Effect of 2OMe substituent on reaction energies for the rearrangement reactions of rhenabenzene.

18. TS Energy profiles calculated for the formation of the rearrangement of 1 to 2. The relative electronic energies and Gibbs free energies at 298 K (in parentheses) are given in kcal mol-1.

19. My work DFT Package : Gaussian 03 Method: m05 basis sets : 6-31G * LanL2DZ (Rh (z(f) = 1.350) Si(z(f)= 0.262) P (z(f) =0.340)) bond lengths (Å): Si3-Si4 =2.21321(2.2807),Si2-Si3 =2.21328(2.2294),Si4-C10=1.87771(1.857),Si2-C11=1.87793 (1.871), C10-C11=1.39592(1.413), Si4-Rh=2.51113(2.4806), Si2-Rh=2.51036(2.5231),Si3-Rh= 2.77879 (2.6845), C11-Rh=2.51842(2.323), C10-Rh=2.51852(2.371) H. Yasuda, V. Ya. Lee, A. Sekiguchi ,J. Am. Chem. Soc, 2009, 131, 9902.

20. The Gibbs free energies and the relative electronic energies (in parentheses) are given in kcal/mol

21. Conjugation energies B3LYP Conjugation energies:46.66 kcal/mol [Os] = Os(PH3)2(CO)I Conjugation energies:43.52 kcal/mol GuochenJia, ZhenyangLin,Organometallics 2003, 22, 3898

22. The blue ones have imaginary frequencies Effect of OMe substituent on reaction energies for the rearrangement reactions of rhodasilabenzenes

23. Effect of 2OMe substituent on reaction energies for the rearrangement reactions of rhodasilabenzenes

24. Effect of PMe3 substituent on reaction energies for the rearrangement reactions of rhodasilabenzenes.

25. Effect of PF3 substituent on reaction energies for the rearrangement reactions of rhodasilabenzenes

26. Effect of 2PF3 or 3PF3 substituent on reaction energies for the rearrangement reactions of rhodasilabenzenes

27. Effect of OMe and PF3 substituent on reaction energies for the rearrangement reactions of rhodasilabenzenes

28. TS path 1 Path 2

29. Result Summary 1. The thermodynamic of the Silacyclopentadienyl complexes is more stable than Rhodasilabenzene. 2. Computed how the substituents (OMe,PMe3,PF3) on the metallacycle affect the transformation and found that substituents and their locations on the metallacycle have a significant effect on the thermodynamic of the rearrangement reactions. 3. But can not realize the isomerization from Silacyclopentadienyl complexes to Rhodasilabenzenes. 4. Explore the possible pathway for the Rhodasilabenzene to Silacyclopentadienyl complexes.

30. Next work 1. realize the isomerization from Silacyclopentadienyl complexes to Rhodasilabenzenes by using substituents on the metallacycle 2. Find the reaction pathway from Silacyclopentadienyl complexes to Rhodasilabenzenes.

31. Thanks for your attention . . .