Structure, reactivity and catalytic properties of manganese-hydride amidate complexes

• Published in: Nature chemistry Vol. 14; no. 11; pp. 1233 - 1241
• Main Authors: Wang, Yujie, Liu, Shihan, Yang, Haobo, Li, Hengxu, Lan, Yu, Liu, Qiang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2022; Nature Publishing Group
• Subjects: 639/638/403/934; 639/638/549/884; 639/638/77/888; Alkali metals; Alkoxides; Analytical Chemistry; Biochemistry; Catalysis; Catalysts; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Heavy metals; Hydrogen bonding; Hydrogenation; Inorganic Chemistry; Ketones; Manganese; Metal hydrides; Organic Chemistry; Physical Chemistry; Reactivity
• ISSN: 1755-4330; 1755-4349; 1755-4349
• DOI: 10.1038/s41557-022-01036-6

The high efficiency of widely applied Noyori-type hydrogenation catalysts arises from the N–H moiety coordinated to a metal centre, which stabilizes rate-determining transition states through hydrogen-bonding interactions. It was proposed that a higher efficiency could be achieved by substituting an N–M′ group (M′ = alkali metals) for the N–H moiety using a large excess of metal alkoxides (M′OR); however, such a metal-hydride amidate intermediate has not yet been isolated. Here we present the synthesis, isolation and reactivity of a metal-hydride amidate complex (HMn–NLi). Kinetic studies show that the rate of hydride transfer from HMn–NLi to a ketone is 24-fold higher than that of the corresponding amino metal-hydride complex (HMn–NH). Moreover, the hydrogenation of N -alkyl-substituted aldimines was realized using HMn–NLi as the active catalyst, whereas HMn–NH is much less effective. These results highlight the superiority of M/NM′ bifunctional catalysis over the classic M/NH bifunctional catalysis for hydrogenation reactions. Noyori-type hydrogenation catalysts consist of an N–H moiety coordinated to a metal centre. Now, a metal-hydride amidate complex (HMn–NLi) has been isolated and found to have superior reactivity and catalytic performance compared with the corresponding HMn–NH complex, highlighting the superiority of M/NM′ bifunctional catalysis over the classic M/NH bifunctional catalysis for hydrogenation reactions.