Phosphine‐NHC Manganese Hydrogenation Catalyst Exhibiting a Non‐Classical Metal‐Ligand Cooperative H₂ Activation Mode

Abstract

Deprotonation of the MnI NHC‐phosphine complex fac‐[MnBr(CO)3(κ2P,C‐Ph2PCH2NHC)] (2) under a H2 atmosphere readily gives the hydride fac‐[MnH(CO)3(κ2P,C‐Ph2PCH2NHC)] (3) via the intermediacy of the highly reactive 18‐e NHC‐phosphinomethanide complex fac‐[Mn(CO)3(κ3P,C,C‐Ph2PCHNHC)] (6 a). DFT calculations revealed that the preferred reaction mechanism involves the unsaturated 16‐e mangana‐substituted phosphonium ylide complex fac‐[Mn(CO)3(κ2P,C‐Ph2P=CHNHC)] (6 b) as key intermediate able to activate H2 via a non‐classical mode of metal‐ligand cooperation implying a formal λ5‐P–λ3‐P phosphorus valence change. Complex 2 is shown to be one of the most efficient pre‐catalysts for ketone hydrogenation in the MnI series reported to date (TON up to 6200).

Retracted: The Manganese(I)‐Catalyzed Asymmetric Transfer Hydrogenation of Ketones: Disclosing the Macrocylic Privilege

“…Driven by the importance of enantiopure alcohols, [2] iron catalysts have been developed for the asymmetric hydrogenation of polar double bonds. [3][4][5][6][7] In contrast, manganese remained unexplored until 2016, when it was applied in the non-enantioselective hydrogenation of polar multiple bonds with H 2 [8][9][10][11][12][13][14][15] and, more rarely,u nder hydrogen-transfer conditions. [16][17][18] Similarly,e nantioselective Mn I catalysts for ketone hydrogenation with H 2 (Clarke: A, [19] Beller: B, [20] Han and Ding: C, [21] and ours: D [22] )a re more numerous than those for asymmetric transfer hydrogenation (E [23] and F [24] ; Figure 1).…”

Prizes of the Société Chimique de France

“…Sortais' research focuses on the development of novel molecular catalysts based on abundant 3d transition metals such as iron, nickel, and manganese for applications in catalytic reduction and direct C−H bond activation processes. In a Communication in Angewandte Chemie he has recently reported on a phosphine‐NHC manganese hydrogenation catalyst for cooperative dihydrogen activation …”

Preise der Société Chimique de France

“…Sortais entwickelt molekulare Katalysatoren mit 3d‐Übergangsmetallen wie Eisen, Nickel und Mangan für katalytische Reduktionen und direkte C‐H‐Aktivierungen. Er berichtete kürzlich in einer Angewandte‐Chemie ‐Zuschrift über einen Phosphan‐NHC‐Mangan‐Hydrierkatalysator für die kooperative Aktivierung von Diwasserstoff …”