The thermal chemistry of 1-chloro-3-iodopropane (ClC{sub 3}H{sub 6}I) adsorbed on Pt(111)
This paper describes the thermally activated surface chemistry of 1-chloro-3-iodopropane, ClC{sub 3}H{sub 6}I, on Pt(111). The work is related to companion studies on other C{sub 3}adsorbates investigated in the laboratory, including cyclopropane, c-C{sub 3}H{sub 6}. HREELS and XPS indicate negligible dissociation of ClC{sub 3}H{sub 6}I during adsorption at 100 K. During TPD, no ClC{sub 3}H{sub 6}I desorbs for coverages below 0.4 ML. For higher, but not multilayer coverages, parent ClC{sub 3}H{sub 6}I desorption occurs in two peaks, 200 and 230 K. After even larger doses, unsaturable multilayer desorption occurs at 170 K. HREELS indicates that most C-I bonds dissociate by 205 K. The following reaction paths are proposed on the basis of TPD and HREELS results. When the C-I bond breaks, 3-chloropropyl fragments, C{sub (a)}H{sub 2}CH{sub 2}CH{sub 2}Cl, are formed and these either lose HCl to form {eta}{sup 3}- or {eta}{sup 1}-allyl or lose a {beta}-hydrogen to form 3-chloro-di-{sigma}-propylene. Some {eta}{sup 3}-allyl groups hydrogenate to either propylene, some of which desorbs at 240 K, or n-propyl, some of which hydrogenates to release propane at 250 K. Other {eta}{sup 3}-allyl groups isomerize to {eta}{sup 1}-allyl. At 250 K, 3-chloro-di-{sigma}-propylene eliminates chlorine as HCl and also releases H atoms that hydrogenate neighboring C{sub 3} fragments. The {eta}{sup 1}-allyl fragment either hydrogenates and desorbs as propylene at 325 K or isomerizes to propylidyne. Propyl and di-{sigma}-propylene moieties rearrange to form propylidyne or release propylene at 325 K. Interestingly, there is some benzene desorbing at 375 K. To account for it, a diene metallacycle is suggested. Atomic iodine desorbs at 825 K. Comparisons of the thermal chemistry of ClC{sub 3}H{sub 6}I on Ag(111) and Ni(100) are made as are comparisons of ClC{sub 3}H{sub 6}I with other C{sub 3} adsorbates on Pt(111).
- Research Organization:
- Univ. of Texas, Austin, TX (US)
- Sponsoring Organization:
- USDOE; Robert A. Welch Foundation
- OSTI ID:
- 20003203
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Vol. 103, Issue 44; Other Information: PBD: 4 Nov 1999
- Country of Publication:
- United States
- Language:
- English
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