Preparation and reactivity of molybdenum complexes bearing pyrrole-based PNP-type pincer ligand

Abstract

Molybdenum complexes bearing an anionic pyrrole-based PNP-type pincer ligand have been prepared and have been found to work as catalysts for the conversion of N2 into NH3 under ambient conditions.

Dinitrogen Fixation: Rationalizing Strategies Utilizing Molecular Complexes

“… [41] Recently, the introduction of an anionic pyrrole‐based PNP ′ ligand allowed the isolation of the complex [Mo(PNP′)I 2 ] ( 258 ), which reacted with N 2 in the presence of metallic lithium at −50 °C to afford the dimeric Mo IV nitride complex [{Li(PhMe)Mo≡N(PNP′)I} 2 ] ( 259 ) (Scheme 50 b). [201] Complex 259 catalyzes the formation of NH 3 (12 equiv) in the presence of SmI 2 and ethylene glycol, via a similar mechanism than the one proposed for complex 20 . It is interesting to note that contrary to the previously reported PNP complexes, the coordination and cleavage of N 2 is reversible in this case.…”

Molybdenum‐Mediated N2‐Splitting and Functionalization in the Presence of a Coordinated Alkyne

“…Preliminary experiments indicate that this holds true for the corresponding reactions of 3 with Me 3 SiCl and EtI, although the resulting N-functionalized products have only been observed by NMR spectroscopy so far (see Supporting Information). Nishibayashi, Schneider, Cummins and others demonstrated that NH 3 , N(SiMe 3 ) 3 , MeCN or PhCN may be generated and released from related (N-H)-, (N-SiMe 3 )-, (N-Et)-or (N-C(O)Ph)-functionalized molybdenum imido complexes, either in a catalytic (NH 3 , N(SiMe 3 ) 3 ) [5] or in a stoichiometric fashion (MeCN, PhCN). [18] In a first screening for related stoichiometric follow-up functionalization reactions, a particularly remarkable transformation was discovered when [10][OTf] was reacted with trans-2,3-epoxybutane in MeCN.…”

“…Mes 3 Mo) were developed [2] and shown to split N 2 as well, [3] while Schrock and co-workers demonstrated that this challenging transformation may also be accomplished using a POCOP-molybdenum pincer complex with a tetragonally coordinated molybdenum center. [4] Nishibayashi, [5] Schneider [6] and MØzailles [7] augmented and advanced this approach by employing different octahedral or square pyramidal PNP-, P(NH)P-and PPPmolybdenum precursors for the cleavage of N 2 , which underlines the importance of Schrocks finding in retrospective.…”

Synergy between metals for small molecule activation: Enzymes and bio-inspired complexes

“…In the context of a multimetallic strategy, the process of dinitrogen reduction to ammonia was made catalytic by Nishibayashi and co-authors, employing a series of binuclear complexes supported by pincer ligands [188][189][190][191][192][193][194]. Among them, the dinitrogen-bridged dimolybdenum(0)-dinitrogen complex bearing a tridentate PNP-type pincer ligand [Mo(N2)2( tBu PNP)(PMe2Ph)], is not catalytically active [196]; and (ii) protonation of mononuclear theoretical models [Mo(N2)3( tBu PNP)] is predicted to be thermodynamically unlikely [190].…”