Bromine abstraction versus dehydrogenation in the reaction of gaseous niobium clusters with saturated and unsaturated organic bromides
✍ Scribed by Li Song; M.A. El-Sayed
- Publisher
- Elsevier Science
- Year
- 1988
- Tongue
- English
- Weight
- 542 KB
- Volume
- 152
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
Small gaseous niobium clusters (Nb,, x= l-12) synthesized by the laser evaporation technique are reacted with I-bromopropene, 3-bromopropene, bromcethane, and 2-bromopropane in a fast flow reactor. Whrle Br abstraction on all Nb clusters takes place with both saturated and unsaturated bromides, addition-dehydrogenation occurs only with the unsaturated compounds at similar concentrations.
The abstraction reaction probability is independent ofr, but the dehydrogenation reaction has a threshold (at x= 6) beyond which the reaction probability is greatly enhanced, and increases with cluster size from x=6 to 10. Thus the two reactions (bromide abstraction and addition-dehydrogenation)
are not competitive, and may result from different types of collisions, impulsive and sticky collisions, respectively.