EFFECT OF LOCALIZED UNSATURATION ON THE SCALAR EXCHANGE COUPLING IN FLEXIBLE BIRADICALS

被引：24

作者：

FORBES, MDE

机构：

[1] Department of Chemistry, Venable and Kenan Laboratories, University of North Carolina, Chapel Hill

来源：

JOURNAL OF PHYSICAL CHEMISTRY | 1993年 / 97卷 / 13期

关键词：

D O I：

10.1021/j100115a051

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Time-resolved electron paramagnetic resonance (TREPR) spectra of flexible biradicals containing one and two double bonds are reported. Simulation of the strongly spin-polarized spectra allows determination of the scalar electronic exchange coupling J and the encounter rate k(en) between the two radical centers. Comparison of each unsaturated biradical with the saturated analogue of similar chain length shows that the J coupling increases with the double bonds present. This and other effects, such as that of the solvent on saturated biradical EPR spectra, are modeled and discussed in terms of both through-bond (TB) and through-solvent (TS) coupling mechanisms. Monte Carlo simulations of the chain dynamics and semiempirical molecular orbital calculations of overlap integrals support the hypothesis that isolated trans double bonds decrease the TS component of the J coupling while increasing the TB component.

引用

页码：3390 / 3395

页数：6

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