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.

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We investigated the reactivity and bonding of perfluoroethyl groups (C2F5) on Cu(111) under ultra high vacuum conditions. Perfluoroethyl moieties bonded to the surface were generated by the dissociative adsorption of perfluoroethyl iodide. Temperature-programmed reaction/desorption (TPR/D) and reflection- adsorption infrared spectroscopy (RAIRS) revealed abounding reaction pathways, and a variety of intermediates were either identified or inferred. The major desorption products, hexafluoro-2-butyne and hexafluorocyclobutene, were detected at 360K and 440K, and some octafluorobutene was observed at 320K at higher coverages, implicating that two fluorine atoms were abstracted step-by-step from the C2F5 on Cu(111). Two sets of signature IR bands were recognized. One set (2054cm-1, 1409cm-1, 1210cm-1) was found to correlate with the surface-bound trifluorovinyl moieties which were also confirmed by directly generating this species from trifluorovinyl iodide. The other set of vibrational features (1322cm-1, 1224cm-1, 950cm-1) presumably implied the trifluoro- ethylidyne intermediate on the surface. Hence, C2F5(ad) underwent the £\-F and £]-F elimination reactions in sequence to yield trifluorovinyl which eventually led to hexafluoro-2-butyne. The alternative route was that C2F5(ad) proceeded via the £\-F elimination reaction twice to render trifluoroethylidyne which ultimately resulted in hexafluorocyclobutene. To our knowledge, the occurrence of the sequential £\-F and£]-F elimination pathway, or the double £\-F elimination reaction has never been observed in any single system.

ªí­±¤Æ¾Ç»â°ì¤¤¡A¬ã¨s¹L´çª÷Äݳ洹ªí­±¤W§lªþºA¤A°ò(C2H5)¤§¤ÏÀ³¡A¤w¦³¬Û·í¦hªº³ø¾É¡C¨ä¦@ÃѬ°£]-H®ø¥h(£]-elimination)§Î¦¨¤A²m(C2H4)²æªþ¬O¥D­n¤ÏÀ³¸ô®|¡C¥»¬ã¨s«h¥H¤£¦Pµ{«×¬t¨ú¥Nªº¤A°ò(ethyl)¡GCF3CF2-¡BCHF2CF2-¡BCF3CHF-¡BCF3CH2-¤ÎCH3CH2-§@¬°¹ï·Ó¡A§lªþ¦bCu(100)³æ´¹­±¤W¥Hµ{·Å¤ÏÀ³/²æªþ(TPR/D)¹êÅç±´°Q¤ÏÀ³¾÷ºc¡Aµ²ªGÅã¥Ü«e¨âºØ¼Ë«~¥ý¶i¦æ£\-F®ø¥h§Î¦¨Ethylideneªí­±¤¤¶¡Åé¡A«eªÌ¦A¦Û¨­°¸¦X©ó350K¥Í¦¨CF3-CF=CF-CF3¡A¦Ó«áªÌ°¸¦X©ó300K¥Í¦¨CHF2-CF=CF-CHF2¡C«á¤TºØ¼Ë«~«hµo¥Í£]®ø¥hª½±µ²£¥ÍCHF=CF2(310K)¡BCH2=CF2(225K)©MCH2=CH2(250K)¡C¥Ñ©ó­n¶i¦æ¸û§C·Å¤§£]®ø¥h¤ÏÀ³®É¡A¹L´çºA§e¥­­±¤ÎEclipsedºc«¬(¦p¥k¹Ï)¡CÂǥѦ¹¬Ý¥X«e¨âºØ¼Ë«~¤§£]¸ô®|¹L´çºA¬O¨ã¦³¨â¹ïF-F¤¬¥¸§@¥Î¡A³o¨Ï±o¹L´çºA¸û¤£Ã­©w¡A¯à»Ùª@°ª¾É­P¤ÏÀ³¸ô®|Â੹¬Û¹ï¯à»Ù¥i¯à¸û§C¤§£\®ø¥h¡C«á¤TºØ¼Ë«~¦æ£]®ø¥h¤§¹L´çºA¦]¦³¸û¤ÖF-F±Æ¥¸¡A©Ò¥H¦æ£]®ø¥h¤ÏÀ³¡C¨Ï¥Î¼ÒÀÀ­pºâªºµ²ªG¤]Åã¥Ü¡A·í©Mª÷ÄÝÁäµ²ªº£\ºÒ¤W¨ã¬t¨ú¥N®É°£³y¦¨ªºÁä¯àÅܱj¡A¥ç·|³y¦¨¦b¹L´çºA¦b¶i¦æª÷ÄÝ-ºÒÁäÂ_µõ®É¯à»Ù¤É°ª¦Ó¶}±Ò¬Û¹ï¯à»Ù¥i¯à¸û§C¤§£\®ø¥h³q¹D¡C¬ã¨sµ²ªG©Ò¤Ï¬M¤A°ò¤W¬t¨ú¥N¦ì¸m¤Îµ{«×¤£¦P©Ò³y¦¨ªº¤ÏÀ³¸ô®|ªº¿ï¾Ü©Ê¡A§¡¥i¥Ñ¤W­z¹L´çºA¤©¥H¦X²zªº¸ÑÄÀ¡C

Abstract The reactivity and bonding of allyl groups (C3H5) on a Ag(111) surface have been investigated under ultrahigh vacuum conditions by temperature-programmed reaction/desorption (TPR/D) and reflection-adsorption infrared spectroscopy (RAIRS). The atomically clean surface was achieved by Ar+ sputtering and verified by AES. The surface crystallinity was assured by LEED. Surface -bound allyl groups were generated by dissociative adsorption of allyl halides. Our study shows that the C-X (X= I or Cl) bond can be ruptured below 200K to render adsorbed allyl species. Upon further heating, three gas-phase products were detected at ~280 K, 295 K and 320 K in the TPR/D spectra, which are attributed to 1,5-hexadiene, allene, and propene, respectively. These results suggest that allyl undergoes

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