Presentation on theme: "Isomerization from Silacyclopentadienyl Complexes to Rhodasilabenzenes, Possible or Not? Ying huang."— Presentation transcript:
Isomerization from Silacyclopentadienyl Complexes to Rhodasilabenzenes, Possible or Not? Ying huang
Contxet Background My work Result Summary and next work
1. What’s metallabenzene complexes?. [M] = ML n, ML n-1 X or ML n-2 X 2 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 Metallabenzene
In 1982 Since then Various metallaaromatics have been reported. the first metallabenzene W.R. Roper, J. Chem. Soc. Chem.Commun. 1982, 811
Rhodabenzene No rhodabenzene has yet been isolated. only rhodabenzvalene was isolated at -30 ℃ in 2002. M. M. Haley, Organometallics,2002,21,4320 48%
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
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. But simple neutral silaaromatic compounds are known to be highly reactive.
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 Reason
synthesis No silabenzene stable at ambient temperature has ever been reported until 1999. 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl N. Tokitoh,Pure Appl. Chem, 1999,71, 495.
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 X-ray Raman Schematic drawings of the vibrational modes for the strongest in-plane vibrations of benzene and silabenzene
N.Tokitoh,Organometallics, 2005, 24, 6141 Half-Sandwich complexes containing Si
A. Sekiguchi,J. Am. Chem. Soc,2009, 131, 9902 Rhodium Half-Sandwich 47% The first group 9 metal complex with the heavy cyclopentadienyl ligand and the first heavy cyclopentadienyl complex of half-sandwich type.
1. The thermodynamic of the Silacyclopentadienyl complexes is more stable than Rhodasilabenzene. 2. Computed how the substituents (OMe,PMe 3,PF 3 ) 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. Result Summary
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. Next work