Reactivity of [Ce(NR2)3] (R = SiMe3) with Prospective Carbon Atom Transfer Reagents

Kent, Greggory T.; Staun, Selena L.; Hayton, Trevor W.

doi:10.1021/acs.organomet.0c00186

Cited by 11 publications

(12 citation statements)

References 58 publications

(143 reference statements)

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“…In order to promote the delivery of a C atom or CR group, at least one C-C bond has to be cleaved, which can be achieved by methods such as heating (38), photolysis (38), or reduction (36,39). While 2-W remains unchanged when irradiated with a 75-W Xe lamp and decomposes when heated at reflux in THF under an inert atmosphere, reduction with one equivalent of a strong reducing agent like potassium naphthalenide leads to the new cluster 3.…”

Section: Resultsmentioning

confidence: 99%

Partial synthetic models of FeMoco with sulfide and carbyne ligands: Effect of interstitial atom in nitrogenase active site

Bailey

Scott

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Nitrogen-fixing organisms perform dinitrogen reduction to ammonia at an Fe-M (M = Mo, Fe, or V) cofactor (FeMco) of nitrogenase. FeMco displays eight metal centers bridged by sulfides and a carbide having the MFe7S8C cluster composition. The role of the carbide ligand, a unique motif in protein active sites, remains poorly understood. Toward addressing how the carbon bridge affects the physical and chemical properties of the cluster, we isolated synthetic models of subsite MFe3S3C displaying sulfides and a chelating carbyne ligand. We developed synthetic protocols for structurally related clusters, [Tp*M’Fe3S3X]n−, where M’ = Mo or W, the bridging ligand X = CR, N, NR, S, and Tp* = Tris(3,5-dimethyl-1-pyrazolyl)hydroborate, to study the effects of the identity of the heterometal and the bridging X group on structure and electrochemistry. While the nature of M’ results in minor changes, the chelating, μ3-bridging carbyne has a large impact on reduction potentials, being up to 1 V more reducing compared to nonchelating N and S analogs.

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Section: Resultsmentioning

confidence: 99%

Partial synthetic models of FeMoco with sulfide and carbyne ligands: Effect of interstitial atom in nitrogenase active site

Bailey

Scott

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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“…The C1–C2 and C1–C3 distances are 1.389(5) and 1.404(5) Å, respectively, which are comparable to those of the Ce analogue (1.380(5) and 1.393(5) Å) and the free ligand (1.405(3) Å) . The C2–C3 distances in 1 (1.361(5) Å), [(NR 2 ) 3 Ce(BAC)], and free ligand are also comparable. , …”

Section: Resultsmentioning

confidence: 81%

“…Complex 1 crystallizes in the monoclinic space group P 2 1 /c and features a highly distorted tetrahedral geometry about the U(III) center (Figure ). It is isomorphous with its Ce(III) analogue . The U–N amide distances in 1 (av.…”

Section: Resultsmentioning

confidence: 99%

“…For example, Agapie and co-workers showed that reaction of [Tp*M(μ 3 10 Furthermore, our group recently reported that photolysis of the Ce(III) BAC adduct, [(NR 2 ) 3 Ce(BAC)] (R = SiMe 3 ), results in formation of the methylenecyclopropene species [( i Pr 2 N) 2 C 3 C(N i Pr 2 )(C� CN i Pr 2 )] via the formal dimerization and rearrangement of two BAC fragments, concomitant with release of [Ce(NR 2 ) 3 ] (Scheme 1c). 13 Motivated by these past results, we hypothesized that ligation of BAC to uranium(III) could induce either partial or complete carbon atom transfer to form a carbene, carbyne, or carbide complex. Uranium complexes with these ligand types offer the promise of unique insights into actinide electronic structure.…”

Section: ■ Introductionmentioning

confidence: 99%

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U–C Bond Insertion, Ring-Opening, and C–H Activation in a Uranium Bis(diisopropylamino)cyclopropenylidene (BAC) Adduct

Nguyen

Kent

et al. 2023

Organometallics

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Reaction of [U(NR2)3] (R = SiMe3) with 1 equiv of bis(diisopropylamino)cyclopropenylidene (BAC) in Et2O results in the formation of [(NR2)3U(BAC)] (1), which can be isolated in modest yields. Thermolysis of 1 in C6D6 at 85 °C results in the formation of the ring-opened U(IV) product, [(NR2)2U{N(R)(SiMe2CHC(NiPr2)C(NiPr2)CH)}] (2), which can be isolated in low yields. Mechanistic studies suggest that the formation of 2 proceeds via dissociation of BAC from 1 to regenerate [U(NR2)3], which converts into [U{N(R)(SiMe2 CH2)}(NR2)2] at the elevated temperatures. BAC then inserts into the U–C bond of [U{N(R)(SiMe2 CH2)}(NR2)2] to generate a cyclopropenyl intermediate, which undergoes ring opening and C–H activation to afford the final product, 2. We hypothesize that the ring-opening generates an unobserved carbene intermediate. Notably, thermolysis of a 1:1 mixture of independently prepared [U{N(R)(SiMe2 CH2)}(NR2)2] and BAC results in clean formation of 2, providing strong support for the proposed mechanism. The formulations of both 1 and 2 were confirmed by X-ray crystallography. Theoretical calculations indicate that the hypothesized uranium carbene intermediate features strong U–C bonding, potentially with some carbyne character in the electronic structure.

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“…15,36 In order to promote the delivery of a C atom or CR group, at least one C-C bond has to be cleaved, which can be achieved by metal sites by methods such as heating 37 , photolysis 37 or reduction. 35,38 While 2-W remains unchanged when irradiated with a 75 W Xe lamp and decomposes when heated at reflux in THF under an inert atmosphere, reduction with one equivalent of a strong reducing agent like potassium naphthalenide leads to the new cluster 3. Instead of generating a neutral, one-electron reduced form of 2-W and KBPh4 as byproduct, product 3 loses the μ3-Cl ligand as KCl likely driven by precipitation (Figure 2), leaving an open triangular Fe3 face, as demonstrated by XRD characterization (Figure 2).…”

Section: Resultsmentioning

confidence: 99%

Cluster Models of FeMoco with Sulfide and Carbyne Ligands: Effect of Interstitial Atom in Nitrogenase Active Site

Le¹,

Bailey²,

Scott³

et al. 2021

Preprint

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Nitrogen-fixing organisms perform dinitrogen reduction to ammonia at an iron-M (M = Mo, Fe, or V) cofactor (FeMco) of nitrogenase. FeMoco displays eight metal centers bridged by sulfides and a carbide having the MoFe7S8C cluster composition. The role of the carbide ligand, a unique motif in protein active sites, remains poorly understood. Toward addressing its function, we isolated synthetic models of subsite MFe3S3C displaying sulfides and a carbyne ligand. We developed synthetic protocols for structurally related clusters, [Tp*MFe3S3X]n-, where M = Mo or W, the bridging ligand X = CR, N, NR, S, and Tp* = tris(3,5-dimethyl-1-pyrazolyl)hydroborate, to study the effects of the identity of the heterometal and the bridging X group on structure and electrochemistry. While the nature of M results in minor changes, the μ3-bridging ligand X has a large impact on reduction potentials, with differences higher than 1 V, even for the same formal charge, the most reducing clusters being supported by the carbyne ligand.

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Reactivity of [Ce(NR₂)₃] (R = SiMe₃) with Prospective Carbon Atom Transfer Reagents

Cited by 11 publications

References 58 publications

Partial synthetic models of FeMoco with sulfide and carbyne ligands: Effect of interstitial atom in nitrogenase active site

Partial synthetic models of FeMoco with sulfide and carbyne ligands: Effect of interstitial atom in nitrogenase active site

U–C Bond Insertion, Ring-Opening, and C–H Activation in a Uranium Bis(diisopropylamino)cyclopropenylidene (BAC) Adduct

Cluster Models of FeMoco with Sulfide and Carbyne Ligands: Effect of Interstitial Atom in Nitrogenase Active Site

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