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Generation of Unsaturated silicon species from acylpolysianes and investigation on their chemical behaviors

从酰基聚硅烷中生成不饱和硅物种及其化学行为研究

基本信息

批准号：
15550038
负责人：
OHSHITA Joji
金额：
$ 2.43万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15550038/
关键词：
Acylpolysilane Silene Thermal Isomerization Kinetic Studies 反応速度アシルシラン熱異性化

项目摘要

1.Isomerization of acylpolysilanes of importance in silicon chemistry as a convenient method to produce silenes. However, little is known for the mechanism of the isomerization. To know about the mechanism, we determined the kinetic parameters of the thermal isomerization of variously substituted acylpolysilanes, as being ΔH^≠=25.7-29.3 kcal mol^<-1> and ΔS^≠=-11.5--17.5 cal mol^<-1> K^<-1>. The negatively large activation entoropies and the fact that introduction of an electron-withdrawing group on the carbonyl carbon facilitated the isomerization, clearly indicated the intramolecular concerted mechanism. The molecular orbital calculations on a model system also suggested the four-centered transition state. The silenes thermally generated from acylpolysilanes always gave [2+4] adducts as the major products by the reactions with 2,3-dimethylbutadiene. In addition to these, silenes from acylpolysilanes bearing an aryl group on the carbonyl carbon gave ene-adducts as the minor products. However, in contrast to this, silenes from alkyl-substituted acylpolysilanes afforded [2+2] cycloadducts as the minor products.2.Thermal and photocheical isomerization of 2,2-bis(acyl)trisilanes and 1,2-bis(acyl)disilanes was investigated, and it was found that these reactions gave products arising from silene intermediates.

1.酰基聚硅烷异构化作为一种简便的合成方法在硅化学中具有重要意义。然而，对异构化的机理知之甚少。为了了解其机理，我们确定了不同取代的酰基聚硅烷热异构化的动力学参数为ΔH^≠=25.7-29.3 kcal mol^<-1>和ΔS^≠=-11.5—17.5 cal mol^<-1> K^<-1>。负大的激活熵和羰基碳上引入吸电子基团促进异构化的事实清楚地表明了分子内协同机制。模型系统的分子轨道计算也表明存在四中心过渡态。由酰基聚硅烷与2,3-二甲基丁二烯反应而热生成的硅烷多以[2+4]加合物为主要产物。除此之外，羰基碳上带有芳基的酰基聚硅烷的硅烷作为次要产物得到烯加合物。然而，与此相反，从烷基取代的酰基聚硅烷中得到的[2+2]环加合物作为次要产物。研究了2,2-双（酰基）三硅烷和1,2-双（酰基）二硅烷的热异构化和光异构化反应，发现这些反应产生由硅烯中间体生成的产物。