Nakazawa Hiroshi, Itazaki Masumi, Kamata Kouji, Ueda Kensuke
Department of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan.
Chem Asian J. 2007 Jul 2;2(7):882-8. doi: 10.1002/asia.200700076.
The first example of the catalytic C-CN bond cleavage of acetonitrile as well as Si-CN bond formation have been achieved in the photoreaction of MeCN with Et3SiH promoted by [Cp(CO)2FeMe]. This catalytic system is applicable to other organonitriles. Several iron complexes [(eta(5)-C5R5)(CO)2FeR'] (R5 = H5, H4Me, Me5, H4SiMe3, H4I, H4P(O)(OMe)2; R' = SiMe3, CH2Ph, Me, Cl, I) were examined as catalyst, and [Cp(CO)2FeMe] was found to be the best precursor. A catalytic reaction cycle was proposed, which involves oxidative addition of Et3SiH to [Cp(CO)FeMe], reductive elimination of CH4 from [Cp(CO)FeMe(H)(SiEt3)], coordination of RCN to [Cp(CO)Fe(SiEt3)], silyl migration from Fe to N in the coordinated RCN, and dissociation of Et3SiNC from Fe. The reaction with MeCN of [Cp(CO)Fe(py)(SiEt3)], which was newly prepared and determined by X-ray analysis, and the reaction of Et3SiH with MeCN in the presence of a catalytic amount of [Cp(CO)Fe(py)(SiEt3)] showed that the 16-electron species [Cp(CO)Fe(SiEt3)] is the active species in the catalytic cycle (TON up to 251).
在由[Cp(CO)₂FeMe]促进的MeCN与Et₃SiH的光反应中，首次实现了乙腈催化C-CN键的裂解以及Si-CN键的形成。该催化体系适用于其他有机腈。研究了几种铁配合物[(η⁵-C₅R₅)(CO)₂FeR']（R₅ = H₅、H₄Me、Me₅、H₄SiMe₃、H₄I、H₄P(O)(OMe)₂；R' = SiMe₃、CH₂Ph、Me、Cl、I）作为催化剂，发现[Cp(CO)₂FeMe]是最佳前体。提出了一个催化反应循环，其中包括Et₃SiH向[Cp(CO)FeMe]的氧化加成、[Cp(CO)FeMe(H)(SiEt₃)]中CH₄的还原消除、RCN与[Cp(CO)Fe(SiEt₃)]的配位、在配位的RCN中硅基从Fe迁移至N以及Et₃SiNC从Fe解离。新制备并通过X射线分析确定的[Cp(CO)Fe(py)(SiEt₃)]与MeCN的反应，以及在催化量的[Cp(CO)Fe(py)(SiEt₃)]存在下Et₃SiH与MeCN的反应表明，16电子物种[Cp(CO)Fe(SiEt₃)]是催化循环中的活性物种（TON高达251）。
