Activation of manganese nitrido complexes by Brønsted and Lewis acids. Crystal structure and asymmetric alkene aziridination of a chiral salen manganese nitrido complex

Ho, Chi Ming; Lau, Tai‐Chu; Kwong, Hoi‐Lun; Wong, Wing Tak

doi:10.1039/a903605i

Cited by 50 publications

(32 citation statements)

References 12 publications

(9 reference statements)

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“…Thus, the manganese center in 39 has a trigonal bipyramidal geometry (Figure 8). The Mn(V)−N(nitride) bond length of 1.546(3) Å in 39 is on the long end of the range of corresponding bond distances of well-characterized terminal manganese(V) nitrides, 197 and is even longer than its congener in the manganese(IV) complex 37 (1.524(3) Å). The Mn(V)−C(carbene) bond lengths were observed to be 2.054(2) Å in length.…”

Section: Complexes Of Manganesementioning

confidence: 99%

“…From their rich electronic structures, one could assume the presence of similarly rich chemical properties. While the reported C–H activation and group-transfer reactions of manganese, iron, and cobalt imido and nitrido species have shown the tip of the iceberg, − ,− ,,− ,,− ,,,, other attractive reactivity patterns of 3d metal–ligand multiple bonds beckon, for example, olefin metathesis and inert C–H bond insertion. The development of the untapped reactivity and vast potential catalytic applications of these complexes will continue to motivate research in this fascinating field.…”

Section: Summary and Perspectivementioning

confidence: 99%

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High-Oxidation-State 3d Metal (Ti–Cu) Complexes withN-Heterocyclic Carbene Ligation

et al. 2018

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High-oxidation-state 3d metal species have found a wide range of applications in modern synthetic chemistry and materials science. They are also implicated as key reactive species in biological reactions. These applications have thus prompted explorations of their formation, structure, and properties. While the traditional wisdom regarding these species was gained mainly from complexes supported by nitrogen- and oxygen-donor ligands, recent studies with N-heterocyclic carbenes (NHCs), which are widely used for the preparation of low-oxidation-state transition metal complexes in organometallic chemistry, have led to the preparation of a large variety of isolable high-oxidation-state 3d metal complexes with NHC ligation. Since the first report in this area in the 1990s, isolable complexes of this type have been reported for titanium(IV), vanadium(IV,V), chromium(IV,V), manganese(IV,V), iron(III,IV,V), cobalt(III,IV,V), nickel(IV), and copper(II). With the aim of providing an overview of this intriguing field, this Review summarizes our current understanding of the synthetic methods, structure and spectroscopic features, reactivity, and catalytic applications of high-oxidation-state 3d metal NHC complexes of titanium to copper. In addition to this progress, factors affecting the stability and reactivity of high-oxidation-state 3d metal NHC species are also presented, as well as perspectives on future efforts.

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Section: Complexes Of Manganesementioning

confidence: 99%

Section: Summary and Perspectivementioning

confidence: 99%

High-Oxidation-State 3d Metal (Ti–Cu) Complexes withN-Heterocyclic Carbene Ligation

et al. 2018

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“…[53][54][55][56][57][58][59][60][61][62][63][64][65][66] Lau and coworkers previously reported salen manganese nitrido complexes that were activated for stoichiometric aziridination of alkenes following protonation with a Brønsted acid or addition of electrophiles. [67][68][69] Chirik and coworkers demonstrated proton-coupled electron transfer (PCET) at salen manganese nitrido complexes to form ammonia through either photodriven 70,71 or thermal 72 pathways. Although the bond dissociation free energies (BDFEs) at transition metal imidos are central in catalytic nitrogen cycles [73][74][75][76][77][78] and C-H activation, [79][80][81][82][83][84] few BDFE values have been measured compared to isoelectronic metal oxido analogues.…”

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confidence: 99%

Cationic Effects on the Effective Hydrogen Atom Bond Dissociation Free Energy of High Valent Manganese Imido Complexes

Léonard

Chantarojsiri

Yang

2021

Preprint

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Local electric fields can alter energy landscapes to impart enhanced reactivity in enzymes and at surfaces. There has been renewed interest on their use in molecular systems, where they can be installed using charged functionalities. Manga-nese(V) salen nitrido complexes (salen = N,N’-ethylenebis(salicylideneaminato)) appended with a crown ether unit con-taining a Na+ (1-Na), K+, (1-K), Ba2+ (1-Ba), Sr2+ (1-Sr), La3+ (1-La), or Eu3+ (1-Eu) cation were investigated to experimen-tally demonstrate the effect of cation-induced electric fields on pKa, E1/2, and the effective bond dissociation free energy (BDFE) of N–H bonds. The series, which includes the manganese (V) salen nitrido without a crown appended, spans 4 units of charge. Bounds for the pKa values of the transient imido complexes were determined by UV-visible and 1H NMR spectroscopy. These values, together with the reduction potentials for the Mn(VI/V) couple measured by cyclic voltamme-try in acetonitrile, were used to calculated the N–H BDFEs of the imidos. Despite spanning >700 mV and >9 pKa units across the series, the hydrogen atom BDFE only spans ~ 5 kcal/mol (between 76 and 81 kcal/mol). These results suggest that incorporation of cationic functionalities is an effective strategy for accessing wide ranges of reduction potentials and pKa while minimally affecting BDFE, which is essential to modulating electron, proton, or hydrogen atom transfer path-ways.

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“…Although catalytic N -acyl nitrene transfer reactions using azides have been reported, the product is contaminated with diazene derivatives as coproducts . On the other hand, the reaction using metal(nitride) complexes as stoichiometric nitrene source affords the desired product in a chemo- and stereoselective manner . These results indicate that N- acyl metal(nitrene), which can be obtained catalytically, would give the desired N -acyl-amidated products without the formation of isocyanates and diazenes as byproducts.…”

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confidence: 99%

Ruthenium-Catalyzed Asymmetric N-Acyl Nitrene Transfer Reaction: Imidation of Sulfide

2020

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The asymmetric nitrene transfer reaction is a useful and strong tool for the construction of nitrogen functional groups such as N-sulfonyl amide and carbamic ester in a highly enantioselective manner. On the other hand, there is a substantial limitation in this filed: the transfer of N-acyl amide via the corresponding nitrene intermediates is still difficult because N-acyl nitrenes undergo undesired nitrene dimerization or Curtius rearrangement. Herein, we achieved highly enantioselective imidation of sulfides via catalytic N-acyl nitrene transfer with (OC)ruthenium–salen complex 2b as the catalyst and 3-substituted 1,4,2-dioxazol-5-ones 1 as the nitrene source. Complex 2b can decompose dioxazolones 1 to the desired N-acyl nitrene intermediates without any activation via heating or UV irradiation, or transfer generating nitrene intermediates to the sulfur atom of sulfides with good to excellent enantioselectivities (≤98% ee) without diazene and isocyanate contamination.

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Activation of manganese nitrido complexes by Brønsted and Lewis acids. Crystal structure and asymmetric alkene aziridination of a chiral salen manganese nitrido complex

Cited by 50 publications

References 12 publications

High-Oxidation-State 3d Metal (Ti–Cu) Complexes withN-Heterocyclic Carbene Ligation

High-Oxidation-State 3d Metal (Ti–Cu) Complexes withN-Heterocyclic Carbene Ligation

Cationic Effects on the Effective Hydrogen Atom Bond Dissociation Free Energy of High Valent Manganese Imido Complexes

Ruthenium-Catalyzed Asymmetric N-Acyl Nitrene Transfer Reaction: Imidation of Sulfide

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