Secondary radical formation and electron spin polarization in systems involving phosphonyl radicals
Secondary radical formation and electron spin polarization in systems involving phosphonyl radicals
复制标题
涉及膦酰自由基的系统中的二次自由基形成和电子自旋极化
DOI：
10.1039/p29900001371
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
N. Simpson
中科院分区：
文献类型：
--
作者：
K. Mclauchlan;N. Simpson
将电子自旋极化的伯膦酰基自由基加成到碳 - 碳双键上会产生仲自由基，其化学特性可通过对其电子自旋共振（ESR）光谱的超精细结构分析获得。这些自由基表现出极化转移过程所特有的自旋极化（CIDEP）特征。CIDEP模式揭示了伯自由基和仲自由基中超精细耦合的相对符号。这些光谱还异常清晰地展现出依赖超精细的弛豫效应，原则上从这些效应中也可得到仲自由基中耦合的相对符号。仲自由基进一步反应形成叔自由基的情况有时也会发生，同样伴有极化转移。给出了一个实例，在该实例中，由于这一过程，这两种自由基中耦合常数符号的差异导致极化的叔自由基光谱中的相位反转。
Addition of electron spin polarized primary phosphonyl radicals to carbon–carbon double bonds yields secondary radicals the chemical identity of which is obtained from the analysis of the hyperfine structure of their ESR spectra. These radicals exhibit spin polarization (CIDEP) characteristic of a polarization transfer process. The CIDEP patterns reveal the relative signs of the hyperfine couplings in the primary and secondary species. The spectra also exhibit the effects of hyperfine-dependent relaxation unusually clearly, from which the relative signs of the couplings may, in principle, be obtained in these secondary radicals also. Further reaction of the secondary radical to form a tertiary one sometimes also occurs, again with polarization transfer. An example is given of an instance in which a difference in the signs of the coupling constants in these two species leads to a phase reversal in the spectrum of the polarized tertiary radical as a result of this process.