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Magnetic Field Effects on Chemical Reactions of Organometallic Compounds

磁场对有机金属化合物化学反应的影响

基本信息

批准号：
02804033
负责人：
HAYASHI Hisaharu
金额：
$ 1.22万
依托单位：
Institute of Physical and Chemical Research
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02804033/
关键词：
radical radical pair magnetic field effect organometallic compounds micelle germyl radical silyl radical triplet state レ-ザ-ホトリシススピンー軌道相互作用

项目摘要

Magnetic field effects on chemical reactions through radical pairs and biradicals have been studied extensively. There have been few reports, however, on the effects of radicals involving heavier atoms than Ne such as Si, S, Ge, and Sn. Recently, we have found that the photolysis of aryl and/or alkyl substituted group 14 element (Si or Ge) compounds in cyclohexane gives group 14 element centered radicals and that the photodecomposition of aryl substituted germanes occurs through their triplet excited states.Thus, we have studied the magnetic field effects on the decomposition of tetraphenyl silane, tetraphenyl germane, methyltriphenyl germane, and dimethyldiphenyl germane in Briji 35 micellar solution and oil emulsion. We have found with the aid of a laser flash photolysis technique that the lifetimes of the generated triplet radical pairs decrease by 52-80 % with increasing magnetic field from 0 T to 1 T, and that the yields of the escaping radicals increase by 5-18 %. This is the first direct observation of the magnetic field effect on the dynamic behavior of germyl radicals. These effects can be explained by a combination of the hyperfine and relaxation mechanisms.Magnetic field effects have also been studied for the photoinduced electron transfer reactions between hexamethydisilane and aromatic nitriles. For p- and o-dicyanobenzenes, the yields of the escaping anion radicals increase by 23 and 18 %, respectively, with increasing field from 0 T to 1.35 T. For 1, 2, 4, 5-tetracyanobenzene and 9, 10-dicyanoanthracene, no magnetic field effect has been observed, because the back electron transfer from the generated radical ion pairs cannot occur on account of their high electron affinities.

磁场对自由基对和双自由基化学反应的影响已被广泛研究。然而，关于涉及比Ne重的原子如Si、S、Ge和Sn的自由基的影响的报道很少。最近，我们发现芳基和/或烷基取代的14族元素的光解（Si或Ge）化合物在环己烷中产生14族元素中心自由基，芳基取代锗烷的光分解是通过三重激发态进行的，因此我们研究了磁场对四苯基硅烷，四苯基锗烷，甲基三苯基锗烷，和二甲基二苯基锗烷在Briji 35胶束溶液和油乳液中的混合物。我们用激光闪光光解技术发现，随着磁场从0 T增加到1 T，产生的三重态自由基对的寿命减少52- 80%，逃逸自由基的产率增加5- 18%。这是第一次直接观察磁场对锗自由基动力学行为的影响。这些效应可以用超精细机制和弛豫机制的结合来解释。我们还研究了磁场对六甲基二硅烷与芳香腈之间光诱导电子转移反应的影响。对于对二氰基苯和邻二氰基苯，随着磁场从0 T增加到1.35T，逸出阴离子自由基的产率分别增加23%和18%。对于1，2，4，5-四氰基苯和9，10-二氰基蒽，没有观察到磁场效应，因为由于它们的高电子亲和势，从所产生的自由基离子对的背电子转移不能发生。