Synthesis of Low-Valent Nickel Complexes in Aqueous Media, Mechanistic Insights, and Selected Applications

• Published in: Organometallics Vol. 33; no. 23; pp. 6796 - 6802
• Main Authors: Morales-Becerril, Illán, Flores-Álamo, Marcos, Tlahuext-Aca, Adrián, Arévalo, Alma, García, Juventino J
• Format: Journal Article
• Language: English
• Published: American Chemical Society 08.12.2014
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om500767p

The synthesis of nickel(0) complexes usually requires the employment of strong reducing agents, including powerful hydride donors such as LiHBEt3, LiAlH4, and DIBAL-H. Herein, we have reduced the Ni(II) complex [(dippe)NiCl2] (1a) at room temperature by using KOH in aqueous media to yield the low-valent complex [Ni(dippe)2] (4a) as the main product, along with the formation of dippeO2. In order to gain some insight into the reaction mechanism, a series of intermediates were isolated and characterized at different reaction stages. As a result, both Ni(II) hydroxo-bridge (2b) and hydride (3b) complexes were identified as key intermediates. Additionally, the use of water as a hydrogen source in nickel-mediated processes was also investigated and successfully applied to the hydrodefluorination, hydrodesulfurization, and hydrogenation of selected organic substrates.