Mechanism of Catalytic Nitrene Transfer Using Iron(I)鈥揑socyanide Complexes

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• 作者：Ryan E. Cowley ; Matthew R. Golder ; Nathan A. Eckert ; Malik H. Al-Afyouni ; Patrick L. Holland
• 刊名：Organometallics
• 出版年：2013
• 出版时间：October 14, 2013
• 年：2013
• 卷：32
• 期：19
• 页码：5289-5298
• 全文大小：488K
• 年卷期：v.32,no.19(October 14, 2013)
• ISSN：1520-6041

文摘

Low-spin iron(I) complexes supported by bulky 尾-diketiminate ligands catalyze the formation of unsymmetric carbodiimides (RN鈺怌鈺怤R鈥? R 鈮?R鈥? from isocyanides and organoazides. In situ EPR studies indicate that the catalytic resting state in these reactions is the tris(isocyanide)iron(I) complex LFe(CNR)₃, and kinetic experiments show that the reaction is inverse second-order in isocyanide concentration, suggesting that two isocyanide molecules dissociate prior to the rate-determining step. An unusual iron鈥揷arbodiimide complex can be isolated independently, and facile displacement of the coordinated carbodiimide by both isocyanide and N₂ demonstrate that product release is not kinetically limiting during catalysis. These experimental data fit a coherent mechanism for the catalytic C鈥揘 coupling reaction, and the implications for catalytic nitrene transfer are discussed.