Homoleptic Organoderivatives of High‐Valent Nickel(III)

Alonso, Pablo J.; Arauzo, Ana B.; García‐Monforte, María Angeles; Martín, António; Menjón, Babil; Rillo, C.; Tomás, Milagros

doi:10.1002/chem.200901259

Cited by 27 publications

(48 citation statements)

References 76 publications

(72 reference statements)

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“…This is rather usual in d 7 complexes, and may also relate to the loss of intensity of the EPR signal at higher temperature. [16,17] In a perfect square planar geometry the g matrix orientation would be as gx = gy >> gz. [18] In the case of [2 + ][SbF6 -], g1 > g2 >> g3 and indeed indicates a predominance of the xy plane (g1 and g2) over the z axis (g3) but with a significant distortion in the xy plane (g1 differs from g2).…”

Section: Scheme 1 Synthesis Of Nickel Complexes 2 and [2 + ][Sbf6 -]mentioning

confidence: 99%

A Tetracoordinated Phosphasalen Nickel(III) Complex

Cao¹,

Nocton²,

Ricard³

et al. 2013

Angew Chem Int Ed

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The oxidation of a Ni(II) complex bearing a tetradentate phosphasalen ligand, which differs from salen by the presence of an iminophosphorane (PN) in place of an imine unit, was easily achieved by addition of a silver salt. The site of this oxidation was investigated with a combination of techniques (NMR, EPR, UV/Vis spectroscopy, X-ray diffraction, magnetic measurements) as well as DFT calculations. All data are in agreement with a high-valent Ni(III) center concentrating the spin density. This markedly differs from precedents in the salen series for which oxidation on the metal was only observed at low temperature or in the presence of additional ligands or anions. Therefore, thanks to the good electron-donating properties of the phosphasalen ligand, [Ni(Psalen)](+) represents a rare example of a tetracoordinated high-valent nickel complex in presence of a phenoxide ligand.

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Section: Scheme 1 Synthesis Of Nickel Complexes 2 and [2 + ][Sbf6 -]mentioning

confidence: 99%

A Tetracoordinated Phosphasalen Nickel(III) Complex

Cao¹,

Nocton²,

Ricard³

et al. 2013

Angew Chem Int Ed

View full text Add to dashboard Cite

show abstract

“…This is rather usual in d 7 complexes, and may also relate to the loss of intensity of the EPR signal at higher temperatures. [16,17] In a perfect squareplanar geometry the g matrix orientation would be as g x = g y @ g z . [18] In the case of 2 + SbF 6 À , it is as g 1 > g 2 @ g 3 and indeed indicates a predominance of the xy plane (g 1 and g 2 ) over the z axis (g 3 ) but with a significant distortion in the xy plane (g 1 differs from g 2 ).…”

mentioning

confidence: 99%

A Tetracoordinated Phosphasalen Nickel(III) Complex

et al. 2013

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The oxidation of a Ni II complex bearing a tetradentate phosphasalen ligand, which differs from salen by the presence of an iminophosphorane (P = N) in place of an imine unit, was easily achieved by addition of a silver salt. The site of this oxidation was investigated with a combination of techniques (NMR, EPR, UV/Vis spectroscopy, X-ray diffraction, magnetic measurements) as well as DFT calculations. All data are in agreement with a high-valent Ni III center concentrating the spin density. This markedly differs from precedents in the salen series for which oxidation on the metal was only observed at low temperature or in the presence of additional ligands or anions. Therefore, thanks to the good electron-donating properties of the phosphasalen ligand, [Ni(Psalen)]+ represents a rare example of a tetracoordinated high-valent nickel complex in presence of a phenoxide ligand.N,N' -ethylenebis(salicylimine) (salen) derivatives constitute a very successful class of ligands that have found numerous applications in inorganic chemistry and catalysis. [1] Their extraordinary popularity comes from their easy synthesis, allowing a variety of skeleton variations, and their ability to coordinate to a great number of different metal ions. Moreover the presence of two phenoxide and imine functions is reminiscent of the coordination environment generated by two histidine and two tyrosine residues, encountered in several enzymes. Thus, in 1998, the one-electron oxidation of a (salen)copper(II) complex was described, and the resulting persistent phenoxy radical was established as a biomimetic functional model of galactose oxidase.[2] Since then, one-electron-oxidized metal salen complexes of firstrow transition metals have received considerable attention. [3] Depending on the nature of the redox-active orbitals, oxidation of salen complexes leads either to high-valent metal centers (metal-centered oxidation) or to species where the ligand is oxidized to a radical (ligand-centered oxidation). Therefore, various factors may affect the oxidation site, as it was nicely illustrated in the case of nickel salen complexes. In noncoordinating solvents, one-electron oxidation occurs on the ligand, and the unpaired electron is highly delocalized over the salen moiety with a small contribution of the nickel orbitals.[3b, 4] However, in coordinating solvents, or in the presence of exogenous ligands such as pyridine or coordinating anions, the geometry of the complex is modified and so is the site of the oxidation, allowing the formation of Ni III complexes.[4a,b, 5] Temperature-dependent behavior, that is, valence tautomerism, was also described in a few examples.[5b, 6] Moreover, the overall electronic distribution may be finely tuned by the substituents of the phenoxide rings. They influence not only the site of the oxidation (which takes place at the most electron-rich phenoxide ring) as evidenced with complexes featuring unsymmetrical salen, [3c, 7] but also the extent of radical delocalization. [3b, 8] The hybridization o...

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“…Large g values account for significant orbital contributions that allow low‐lying states to mix through spin–orbit coupling. This is rather usual in d 7 complexes, and may also relate to the loss of intensity of the EPR signal at higher temperatures 16. 17 In a perfect square‐planar geometry the g matrix orientation would be as g x = g y ≫ g z 18.…”

Section: Methodsmentioning

confidence: 94%

“…Upon oxidation, this complex led to a high‐valent Ni III [20] complex as demonstrated by X‐ray analysis, EPR spectroscopy, magnetic measurements, and visible spectroscopy as well as DFT calculations. 2 + SbF 6 − is therefore one of the rare tetracoordinated Ni III complexes,15, 16, 18a, 21 and to the best of our knowledge the only one featuring a phenoxide ligand. This observation markedly differs from precedents in the salen chemistry where Ni III complexes were observed only at low temperature, or in the presence of additional ligands or anions.…”

Section: Methodsmentioning

confidence: 99%

Boosting Properties of 3D Binder‐Free Manganese Oxide Anodes by Preformation of a Solid Electrolyte Interphase

et al. 2015

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Huge irreversible capacity loss prevents the successful use of metal oxide anodes in Li-ion full cells. Here, we focus on the critical prelithiation step and demonstrate the challenge of electrolyte decomposition on a pristine anode in a full cell. Both an electrochemical activation process (54 h) with Li metal and a new electrolytic process (75 min) without Li metal were used to preform complete solid electrolyte interphase (SEI) layers on 3 D binder-free MnOy -based anodes. The preformed SEI layers mitigated the electrolyte decomposition effectively and widened the working voltage for the MnOy /LiMn2 O4 full cell, which resulted in a big boost of the specific energy to 300 and 200 W h kgcathode (-1) , largely improved cycling stability, and much higher specific power (4200 W h kgtotal (-1) ) compared to conventional Li-ion batteries. Detailed characterization, such as cyclic voltammetry, scanning transmission electron microscopy, and FTIR spectroscopy, gives mechanistic insight into SEI preformation. This work provides guidance for the design of anode SEI layers and enables the application of oxides for Li-ion battery full cells.

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Homoleptic Organoderivatives of High‐Valent Nickel(III)

Cited by 27 publications

References 76 publications

A Tetracoordinated Phosphasalen Nickel(III) Complex

A Tetracoordinated Phosphasalen Nickel(III) Complex

A Tetracoordinated Phosphasalen Nickel(III) Complex

Boosting Properties of 3D Binder‐Free Manganese Oxide Anodes by Preformation of a Solid Electrolyte Interphase

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