Evidence for Orbital-Specific Electron Transfer to Oriented Haloform Molecules
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- 作者：Beike Jia ; Jonathan Laib ; R. F. M. Lobo ; and Philip R. Brooks
- 刊名：Journal of the American Chemical Society
- 出版年：2002
- 出版时间：November 20, 2002
- 年：2002
- 卷：124
- 期：46
- 页码：13896 - 13902
- 全文大小：203K
- 年卷期：v.124,no.46(November 20, 2002)
- ISSN：1520-5126
文摘
Beams of hyperthermal K atoms cross beams of the oriented haloforms CF3H, CCl3H, and CBr3H,and transfer of an electron mainly produces K+ and the X- halide ion which are detected in coincidence.As expected, the steric asymmetry of CCl3H and CBr3H is very small and the halogen end is more reactive.However, even though there are three potentially reactive centers on each molecule, the F- ion yield inCF3H is strongly dependent on orientation. At energies close to the threshold for ion-pair formation (~5.5eV), H-end attack is more reactive to form F-. As the energy is increased, the more productive end switches,and F-end attack dominates the reactivity. In CF3H near threshold the electron is apparently transferred tothe 
*CH antibonding orbital, and small signals are observed from electrons and CF3- ions, indicating"activation" of this orbital. In CCl3H and CBr3H the steric asymmetry is very small, and signals from freeelectrons and CX3- ions are barely detectable, indicating that the *CH antibonding orbital is not activated.The electron is apparently transferred to the CX* orbital which is believed to be the LUMO. At very lowenergies the proximity of the incipient ions probably determines whether salt molecules or ions are formed.
*CH antibonding orbital, and small signals are observed from electrons and CF3- ions, indicating"activation" of this orbital. In CCl3H and CBr3H the steric asymmetry is very small, and signals from freeelectrons and CX3- ions are barely detectable, indicating that the *CH antibonding orbital is not activated.The electron is apparently transferred to the CX* orbital which is believed to be the LUMO. At very lowenergies the proximity of the incipient ions probably determines whether salt molecules or ions are formed.