Four-Coordinate Fe N<sub>2</sub> and Imido Complexes Supported by a Hemilabile NNC Heteroscorpionate Ligand

McSkimming, Alex; Thompson, Niklas B.

doi:10.1021/acs.inorgchem.2c01656

Cited by 7 publications

(28 citation statements)

References 75 publications

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“…29 Deprotonation of the benzyl group of 1H with tBuLi followed by metalation using CoI 2 proceeded smoothly, providing the corresponding high-spin Co(II) complex (1)CoI (2) as a dark green crystalline solid in 60% yield (Scheme 1 and Figure 1). In contrast to the Fe complex (1)FeCl, 29 reduction of 2 could be carried out using traditional one-electron reductants, with Na 0 in Et 2 O being the most convenient (see the Experimental Section). Subsequent crystallization under a dinitrogen atmosphere afforded the dark-red N 2 -bridged dimer [(1)CoN] 2 (3) in 41% isolated yield (Scheme 1 and Figure 1).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The synthesis of ligand precursor 1 H was carried out according to the reported procedures . Deprotonation of the benzyl group of 1 H with t BuLi followed by metalation using CoI 2 proceeded smoothly, providing the corresponding high-spin Co(II) complex ( 1 )CoI ( 2 ) as a dark green crystalline solid in 60% yield (Scheme and Figure ).…”

Section: Resultsmentioning

confidence: 99%

“…The Grignard reagent was prepared from (3,5-(CF 3 ) 2 C 6 H 3 )CH 2 Cl (0.446 g, 1.70 mmol) according to our previously reported procedure. 29 Synthesis of 8. This complex was made similarly to 2 with some alterations.…”

Section: Synthesis Of 7hmentioning

confidence: 99%

“…4,16,19,21−28 We have recently reported a new heteroscorpionate ligand 1 (Scheme 1) featuring a strongly basic alkyl ligand and two weak-field pyrazoles. 29 Conceptually, the carbon donor serves as an "anchor" intended to prevent complete ligand dissociation during multi-electron processes at a bound metal. This strategy has been inspired by the interstitial carbide within the Fe Mo cofactor (FeMoco) of nitrogenase enzymes, for which evidence is increasingly pointing to an analogous role.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Conceptually, the carbon donor serves as an “anchor” intended to prevent complete ligand dissociation during multi-electron processes at a bound metal. This strategy has been inspired by the interstitial carbide within the Fe Mo cofactor (FeMoco) of nitrogenase enzymes, for which evidence is increasingly pointing to an analogous role. − We also reported some initial Fe complex chemistry for 1 and have been interested in extending the chemistry of this ligand to other first-row metals, here Co, with particular focus on controlling N 2 coordination. Herein, we report the synthesis of the binuclear Co(I)–N 2 –Co(I) complex supported by 1 .…”

Section: Introductionmentioning

confidence: 99%

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Dynamic N₂ Binding at High-Spin Co(I) Supported by N,N,C Heteroscorpionates

Fraker

McSkimming

2023

Organometallics

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Controlling N2 binding at transition-metal centers is essential in facilitating its rapid functionalization. Herein, we report the synthesis of high-spin four-coordinate Co–N2 complexes bound by our recently developed class of N,N,C heteroscorpionate ligands. End-on bridging and terminal binding modes for Co-bound N2 are both readily accessed by adjusting the steric profile of the supporting ligand. In the reported complexes, N2 is only weakly bound and is reversibly lost upon application of vacuum or an Ar atmosphere, with concomitant formation of an unusual Co–C–Si 3-center–2e– interaction. This work further demonstrates the power of steric control in modulating small-molecule binding at low valent centers.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Synthesis Of 7hmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Dynamic N₂ Binding at High-Spin Co(I) Supported by N,N,C Heteroscorpionates

Fraker

McSkimming

2023

Organometallics

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Mechanism of Nitrogen Reduction to Ammonia in a Diiron Model of Nitrogenase

Barchenko,

O’Malley,

de Visser

2023

Inorg. Chem.

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Nitrogenase is a fascinating enzyme in biology that reduces dinitrogen from air to ammonia through stepwise reduction and protonation. Despite it being studied in detail by experimental and computational groups, there are still many unknown factors in the catalytic cycle of nitrogenase, especially related to the addition of protons and electrons and their order. A recent biomimetic study characterized a potential dinitrogen-bridged diiron cluster as a synthetic model of nitrogenase. Using strong acid and reductants, the dinitrogen was converted into ammonia molecules, but details of the mechanism remains unknown. In particular, it was unclear from the experimental studies whether the proton and electron transfer steps are sequential or alternating. Moreover, the work failed to establish what the function of the diiron core is and whether it split into mononuclear iron fragments during the reaction. To understand the structure and reactivity of the biomimetic dinitrogen-bridged diiron complex [(P 2 P ′ Ph FeH) 2 (μ-N 2 )] with triphenylphosphine ligands, we performed a density functional theory study. Our computational methods were validated against experimental crystal structure coordinates, Mossbauer parameters, and vibrational frequencies and show excellent agreement. Subsequently, we investigated the alternating and consecutive addition of electrons and protons to the system. The calculations identify a number of possible reaction channels, namely, same-site protonation, alternating protonation, and complex dissociation into mononuclear iron centers. The calculations show that the overall mechanism is not a pure sequential set of electron and proton transfers but a mixture of alternating and consecutive steps. In particular, the first reaction steps will start with double proton transfer followed by an electron transfer, while thereafter, there is another proton transfer and a second electron transfer to give a complex whereby ammonia can split off with a low energetic barrier. The second channel starts with alternating protonation of the two nitrogen atoms, whereafter the initial double proton transfer, electrons and protons are added sequentially to form a hydrazine-bound complex. The latter split off ammonia spontaneously after further protonation. The various reaction channels are analyzed with valence bond and orbital diagrams. We anticipate the nitrogenase enzyme to operate with mixed alternating and consecutive protonation and electron transfer steps.

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Zinc-Catalyzed Hydroboration of Carbon Dioxide Amplified by Borane-Tethered Heteroscorpionate Bis(Pyrazolyl)methane Ligands

Cruz,

Loupy,

Veiros

2024

Inorg. Chem.

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The borane-functionalized (BR 2 ) bis(3,5-dimethylpyrazolyl)methane (L H ) ligands 1a (BR 2 : 9-borabicyclo[3.3.1]nonane or 9-BBN), 1b (BR 2 : BCy 2 ), and 1c (BR 2 : B(C 6 F 5 ) 2 ) were synthesized by the allylation− hydroboration of L H . Metalation of 1a,b with ZnCl 2 yielded the heteroscorpionate dichloride complexes [(1a,b)ZnCl 2 ] 3a,b. The reaction of 1a with ZnEt 2 led to the formation of the zwitterionic complex [Et(1a)ZnEt(THF)] 5. The reaction of complex 3a with two equivalents of KHBEt 3 under a carbon dioxide (CO 2 ) atmosphere gave rise to the formation of the dimeric bis(formate) complex [(1a)Zn(OCHO) 2 ] 2 8, in which its borane moieties intermolecularly stabilize the formate ligands of opposite metal centers. The allylated precursor L allyl and its zinc dichloride, diethyl and bis(formate) complexes [(L allyl )ZnCl 2 ] 2, [(L allyl )ZnEt 2 ] 4, and [(L allyl )Zn(OCHO) 2 ] 7 were also isolated. The catalyst systems composed of 1 mol % of 3a or 3b and two equivalents of KHBEt 3 hydroborated CO 2 at 1 bar with pinacolborane (HBPin) to the methanol-level product H 3 COBPin (and PinBOBPin) in yields of 42 or 86%, respectively. The catalyst systems using the unfunctionalized complex [(L H )ZnCl 2 ] 6 and KHBEt 3 or KHBEt 3 /nOctBR 2 (BR 2 : 9-BBN or BCy 2 ) hydroborated CO 2 to H 3 COBPin but in 2.5-to 6-fold lower activities than those exhibited by 3a,b/KHBEt 3 . The hydroboration of CO 2 using 8 as a catalyst led to yields of 39−43%, comparable to those obtained with 3a/KHBEt 3 . The results confirmed that the catalytic intermediates benefit from the incorporated boranes' intra-or intermolecular stabilizations.

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Four-Coordinate Fe N₂ and Imido Complexes Supported by a Hemilabile NNC Heteroscorpionate Ligand

Cited by 7 publications

References 75 publications

Dynamic N₂ Binding at High-Spin Co(I) Supported by N,N,C Heteroscorpionates

Dynamic N₂ Binding at High-Spin Co(I) Supported by N,N,C Heteroscorpionates

Mechanism of Nitrogen Reduction to Ammonia in a Diiron Model of Nitrogenase

Zinc-Catalyzed Hydroboration of Carbon Dioxide Amplified by Borane-Tethered Heteroscorpionate Bis(Pyrazolyl)methane Ligands

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Four-Coordinate Fe N2 and Imido Complexes Supported by a Hemilabile NNC Heteroscorpionate Ligand

Cited by 7 publications

References 75 publications

Dynamic N2 Binding at High-Spin Co(I) Supported by N,N,C Heteroscorpionates

Dynamic N2 Binding at High-Spin Co(I) Supported by N,N,C Heteroscorpionates

Mechanism of Nitrogen Reduction to Ammonia in a Diiron Model of Nitrogenase

Zinc-Catalyzed Hydroboration of Carbon Dioxide Amplified by Borane-Tethered Heteroscorpionate Bis(Pyrazolyl)methane Ligands

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Product

Resources

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Four-Coordinate Fe N₂ and Imido Complexes Supported by a Hemilabile NNC Heteroscorpionate Ligand

Dynamic N₂ Binding at High-Spin Co(I) Supported by N,N,C Heteroscorpionates

Dynamic N₂ Binding at High-Spin Co(I) Supported by N,N,C Heteroscorpionates