Facile Splitting of Hydrogen and Ammonia by Nucleophilic Activation at a Single Carbon Center

作者：Guido D. Frey, Vincent Lavallo, B. Donnadieu, Wolfgang W. Schoeller, Guy Bertrand · 发表于：Science · 年份：2007 · DOI：10.1126/science.1141474 · 被引用次数：956 · 研究领域：N-Heterocyclic Carbenes in Organic and Inorganic Chemistry、Ammonia Synthesis and Nitrogen Reduction、Catalytic Cross-Coupling Reactions

In possessing a lone pair of electrons and an accessible vacant orbital, singlet carbenes resemble transition metal centers and thus could potentially mimic their chemical behavior. Although singlet di(amino)carbenes are inert toward dihydrogen, it is shown that more nucleophilic and electrophilic (alkyl)(amino)carbenes can activate H2 under mild conditions, a reaction that has long been known for transition metals. However, in contrast to transition metals that act as electrophiles toward dihydrogen, these carbenes primarily behave as nucleophiles, creating a hydride-like hydrogen, which then attacks the positively polarized carbon center. This nucleophilic behavior allows these carbenes to activate NH3 as well, a difficult task for transition metals because of the formation of Lewis acid-base adducts.