Multi-electron reduction facilitated by a trianionic pyridine(diimine) ligand

Cladis, Dennis P.; Kiernicki, John J.; Fanwick, Phillip E.; Bart, Suzanne C.

doi:10.1039/c2cc37193f

Cited by 83 publications

(97 citation statements)

References 39 publications

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“…Refinement of the data (λ = 1.54184 Å, 150 K) revealed a pseudo-octahedral uranium center with an η 5 -Cp* ligand, a tridentate pyridine-(diimine) ligand, and trans terminal oxos ( Figure 2). In contrast to Cp*U( Mes PDI Me )(THF), 18 where the uranium center is deviated from the plane of the Mes PDI Me ligand by 1.059 Å, the uranium is coplanar with Mes PDI Me in 3. The centroid of the η 5 -Cp* ring is calculated to be 2.583 Å from the uranium center, on the order of other uranium(VI) complexes, including C p * 2 U (  N A d ) 2 ( 2 .…”

Section: Journal Of the American Chemical Societymentioning

confidence: 95%

Synthesis, Characterization, and Stoichiometric U–O Bond Scission in Uranyl Species Supported by Pyridine(diimine) Ligand Radicals

et al. 2015

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Two uranium(VI) uranyl compounds, Cp*UO2((Mes)PDI(Me)) (3) and Cp*UO2((t)Bu-(Mes)PDI(Me)) (3-(t)Bu) (Cp* = 1,2,3,4,5-pentamethylcyclopentadienide; (Mes)PDI(Me) = 2,6-((Mes)N=CMe)2C5H3N; (t)Bu-(Mes)PDI(Me) = 2,6-((Mes)N=CMe)2-p-C(CH3)3C5H2N; Mes = 2,4,6-trimethylphenyl), have been synthesized by addition of N-methylmorpholine N-oxide to trianionic pyridine(diimine) uranium(IV) precursors, Cp*U((Mes)PDI(Me))(THF) (1), Cp*U((Mes)PDI(Me))(HMPA) (1-HMPA), and Cp*U((t)Bu-(Mes)PDI(Me))(THF) (1-(t)Bu). These uranyl complexes contain singly reduced pyridine(diimine) ligands suggesting formation occurs via cooperative ligand/metal oxidation. Treating 3 or 3-(t)Bu with stoichiometric equivalents of Me3SiI results in stepwise oxo silylation to form (Me3SiO)2UI2((Mes)PDI(Me)) (5) or (Me3SiO)UI2((t)Bu-(Mes)PDI(Me)) (5-(t)Bu), respectively. Additional equivalents result in full uranium-oxo bond scission and formation of UI4(1,4-dioxane)2 with extrusion of hexamethyldisiloxane. The uranium complexes have been characterized via multinuclear NMR, vibrational, and electronic absorption spectroscopies and, in some cases, X-ray crystallography.

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Section: Journal Of the American Chemical Societymentioning

confidence: 95%

Synthesis, Characterization, and Stoichiometric U–O Bond Scission in Uranyl Species Supported by Pyridine(diimine) Ligand Radicals

et al. 2015

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“…39 Very recently, the U(IV) compound 29 bearing a PDI 3− ligand was synthesised by Bart and co-workers. 40 Upon treatment with azobenzene, the U(V) bis-imide complex 30 containing a PDI 0 ligand was produced (Scheme 20a). The overall 4-electron redox couple is summarised in Scheme 20b, where it can be seen that the uranium donates 1 out of the 4 requisite electrons, whilst the PDI ligand donates the other 3 electrons.…”

Section: Oxidative Addition Involving Redox Non-innocent Ligands or Omentioning

confidence: 99%

“…42 Further studies revealed that the Cp*/Cp* − redox couple is responsible for this reductive reactivity, and the Scheme 20 Oxidative addition of a U(IV) centre by PhNvNPh, in cooperation with the redox non-innocent PDI ligand. 40 resulting Cp* free-radical dimerises to form (C 5 Me 5 ) 2 . 43 These pioneering works evoked the term 'sterically induced reduction' (SIR), which refers to a class of redox reaction in which a conventionally non-oxidisable anionic ligand (L n− ), instead of a metal centre, acts as an electron donor to reduce steric overcrowding.…”

Section: Oxidative Addition Involving Redox Non-innocent Ligands or Omentioning

confidence: 99%

Uranium-mediated oxidative addition and reductive elimination

Liddle

2015

Dalton Trans.

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Oxidative addition, and its reverse reaction reductive elimination, constitute two key reactions that underpin organometallic chemistry and catalysis. Although these reactions have been known for decades in main group and transition metal systems, they are exceptionally rare or unknown for the f-block. However, in recent years much progress has been made. In this Perspective article, advances in uranium-mediated oxidative addition/reductive elimination, since the point that this research area was initiated in the early-1980s, are summarised. We principally divide the Perspective into two parts of oxidative addition and reductive elimination, along with a separate section concerning reactions where there is no change of uranium oxidation state in reactant and product but the reaction has the formal appearance of a 'concerted' reductive elimination/oxidative addition from the perspective of the net result. This body of work highlights that whilst uranium is capable of performing reactions that to some extent conform to traditional reactivity types, novel reactivity that has no counterpart anywhere else can be performed, thus adding to the rich palate of redox chemistry that uranium can mediate.

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“…The resulting complexes would have the potential to act as uranium(III) imido synthons. Redox‐active ligands have been used extensively by Bart and co‐workers in uranium organometallic chemistry to promote multi‐electron reactivity . Most notably, this approach has resulted in the first example of a uranium tris(imido) complex.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Reduction of Uranium(V) Imido Complexes with Redox‐Active Substituents

Mullane

Carroll

Schelter

2017

Chemistry A European J

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Organic azides that contain naphthyl functional groups were used to prepare uranium(V) imido complexes U [=NC(2-naph)Ph ][N(SiMe ) ] (2), U [=NC(2-naph) ][N(SiMe ) ] (3), and U [=N(2-naph)][N(SiMe ) ] (4), and their properties were compared with U [=NCPh ][N(SiMe ) ] (1). The electronic structures of these compounds were investigated by solution electrochemistry studies, which revealed accessible U , U , and naphthalene /naphthalene couples. The uranium(V) naphthylimido complexes were reduced by potassium graphite to yield their uranium(IV) congeners K[U [=NC(2-naph)Ph ][N(SiMe ) ] ] (2-K), K[U [=NC(2-naph) ][N(SiMe ) ] ] (3-K), and K[U [=N(2-naph)][N(SiMe ) ] ] (4-K). The electronic structure of the dianionic compounds were investigated by DFT calculations, and this revealed that the second reduction was ligand-based, which opens the possibility of accomplishing multi-electron redox chemistry by using a tailored multiply-bonded ligand.

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Multi-electron reduction facilitated by a trianionic pyridine(diimine) ligand

Cited by 83 publications

References 39 publications

Synthesis, Characterization, and Stoichiometric U–O Bond Scission in Uranyl Species Supported by Pyridine(diimine) Ligand Radicals

Synthesis, Characterization, and Stoichiometric U–O Bond Scission in Uranyl Species Supported by Pyridine(diimine) Ligand Radicals

Uranium-mediated oxidative addition and reductive elimination

Synthesis and Reduction of Uranium(V) Imido Complexes with Redox‐Active Substituents

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