Investigation of Through-Bond Coupling Dependence on Spacer Structure
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- 作者：Basil P. Paulson ; Larry A. Curtiss ; B. Bal ; Gerhard L. Closs ; and John R. Miller
- 刊名：Journal of the American Chemical Society
- 出版年：1996
- 出版时间：January 17, 1996
- 年：1996
- 卷：118
- 期：2
- 页码：378 - 387
- 全文大小：265K
- 年卷期：v.118,no.2(January 17, 1996)
- ISSN：1520-5126
文摘
Intramolecular electron transfer rate constants in solution aremeasured for radical anions and cations ofmolecules having biphenyl and naphthalene groups as donor and acceptor.The molecules have one or more five-bond hydrocarbon chains between the donor and acceptor groups intrans, gauche, and cis conformations.The ratessuggest that one trans chain is as effective as twogauche chains or three cis chains, consistentwith Hoffmann'sprediction of more effective coupling through transhydrocarbon chains. Ab initio calculations of thecouplings arein reasonable agreement with the experiments. Calculations ofelectronic coupling pathways provide insight intothe reason for the superiority of the trans conformation,which gives constructive interference between the twolargest pathways. The calculations also show that "cross talk"can enhance couplings in cyclic spacers in contrastto its deleterious effect in norbornyl spacers. Comparisons ofcouplings through these spacers with simple hydrocarbonchains require that large nonbonded interactions be taken intoaccount.