In organometallic study, activation of C-F bond is an interesting subject, especially in fluoro-substituted propyl groups, because of their different reactivityn from fluoro-substituted methyl and ethyl groups. In this thesis, fluorinated propyl groups were studied on a Cu(111) surface under ultrahigh vacuum (UHV)
conditions. We have examined the kinetics of the £]-elimination reaction in CF3CF2CH2-Cu, CHF2CF2CH2-Cu, and CF3CH2CH2-Cu. These species all
decompose via £]-elimination to give CF3CF=CH2, CHF2CF=CH2, and CF3CH=CH2. The first two species undergo £]-fluoride elimination and the third
one undergoes £]-hydride elimination. The difference in activation energies between the first two accounts for the charge separation (R-C£]+£_¡KF−£_¡KM+£_) in the transition state proposed by Gellman. The activation energies for £]-hydride
elimination (CF3CH2CH2-Cu) and £]-fluoride elimination (CF3CF2CH2-Cu) was also compared. The activation energy for £]-fluoride elimination is found to be lower than that of £]-hydride elimination. In the studies of reaction pathways for perfluoropropyl groups (n-C3F7-Cu and i-C3F7-Cu) on Cu(111), we discovered novel chemistry in TPD. n-C3F7-Cu undergoes Cu-C homolytic cleavage (radical desorption) at 340 K, whereas i-C3F7-Cu eliminates the £]-fluorine at 365 K. By
changing the Cu-C bond length in the i-C3F7-5Cu models their IR spectra was calculated. We discover that the IR of i-C3F7-5Cu with shorter Cu-C bond (1.728Å) is more similar to the experimental IR spectra. That demonstrates the bond strength of Cu-C bond of i-C3F7-Cu is too strong to undergo Cu-C homolytic cleavage at 340 K. Hence, £]-F decomposition becomes the favorite pathway to i-C3F7-Cu because there are more £]-F atoms available in this moiety.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0803106-145945 |
| Date | 03 August 2006 |
| Creators | Wu, Shin-Mou |
| Contributors | Jong-Liang Lin, Cheng-Lung Chen, Chao-Ming Chiang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0803106-145945 |
| Rights | withheld, Copyright information available at source archive |
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