Reactions of the nickel(I) octaethylisobacteriochlorin anion with alkyl halides

Stolzenberg, Alan M.; Stershic, Matthew T.

doi:10.1021/ja00224a026

Cited by 65 publications

(49 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In many aspects of chemical reactivity (supernucleophilicity, "supersoftness" and high reducing power) these metal-centred anions are essentially different from conventional "electronegative" nucleophiles. 5 and Ni(I) porphyrin anion 6 were claimed to be the most powerful nucleophiles on record. Their ability to react with unactivated aryl and vinyl halides, which are inert towards conventional nucleophiles, forms another aspect of their exceptional nucleophilic reactivity.…”

Section: Introductionmentioning

confidence: 99%

“…Their ability to react with unactivated aryl and vinyl halides, which are inert towards conventional nucleophiles, forms another aspect of their exceptional nucleophilic reactivity. [6][7][8][9][10][11][12][13][14] The term "supersoftness" is used to refer to much higher affinity of metal-centred anions towards organic substrates with soft leaving groups, e.g. higher than usual k I /k OTos or k I /k Br ratios.…”

Section: Introductionmentioning

confidence: 99%

“…higher than usual k I /k OTos or k I /k Br ratios. While evident already in aliphatic S N 2 reactions, [4][5][6]15 in aromatic and vinylic substitution with metal centred anions the leaving group effect is often reversed: from F>>Cl, Br, I typical for Ad N E mechanism it changes to I>Br>Cl>F. [6][7][8]12,[14][15][16][17][18] The last but not least is the high reducing power of metal-centred nucleophiles. Their reactions with organic halides formally considered as nucleophilic are frequently accompanied by the formation of dehalogenated or homocoupled products.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Metal carbonyl anions as model metal-centered nucleophiles in aromatic and vinylic substitution reactions

Sazonov¹,

Ivushkin²,

Artamkina³

et al. 2003

Arkivoc

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Metal carbonyl anions as model metal-centered nucleophiles in aromatic and vinylic substitution reactions

Sazonov¹,

Ivushkin²,

Artamkina³

et al. 2003

Arkivoc

View full text Add to dashboard Cite

show abstract

“…These include some of the relatively more saturated tetraaza macrocyclic complexes first reported by Busch and coworkers, 20 and of the relatively less saturated, porhyrinic complexes described by Fajer and Stolzenberg and their co-workers. [40][41][42][43][44][45][46][47][48][49][50] Among these models, the most fruitful has been that of Ni with the ligand octaethyisobacteriochlorin (OEiBC), a diagram of which is shown below. The octaethyl substituents aid in solubility, but may have other electronic effects.…”

Section: Background On Nickel(i) and On Methyl Com Reductase (Mcr)mentioning

confidence: 99%

“…44 [Ni(OEiBC)] -has not only spectroscopic relevance to MCR red1 , but also exhibits reactivity that has some similarities to that of MCR. 42,48 What is striking about the effectiveness of OEiBC as a model ligand for F 430 is how structurally different the two are. F 430 is a much more highly saturated and more flexible macrocycle than OEiBC, 54 although porphyrinic macrocycles should not be thought of as the rigid disks by which they are so often depicted.…”

Section: Background On Nickel(i) and On Methyl Com Reductase (Mcr)mentioning

confidence: 99%

Overview of ligand versus metal centered redox reactions in tetraaza macrocyclic complexes of nickel with a focus on electron paramagnetic resonance studies

Telser

2010

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

Complexos de cobre(II) (3d 9 , S = 1/2) são estáveis e amplamente investigados por espectroscopia de ressonância paramagnética eletrônica (EPR). Já o isoeletrônico níquel(I) é muito menos comum e muito menos estudado. No entanto, níquel(I) tem interesse biológico, uma vez que o sítio ativo da metil coenzima M redutase (MCR) , S = 1/2) complexes are stable and widely investigated by electron paramagnetic resonance (EPR) spectroscopy. In contrast, isoelectronic nickel(I) is much less common and much less investigated. Nickel(I), however, is of biological interest as the active site of methyl coenzyme M reductase (MCR) contains a tetraaza macrocyclic ligand, F 430 , which coordinates Ni I in its active form, MCR red1 . As result, the redox behavior and spectroscopy of tetraaza macrocyclic complexes of nickel is of importance in biomimetic chemistry. Such efforts are complicated by the difficulty in generating Ni I from their stable, Ni II , precursors. Reduction of Ni II macrocyclic complexes can afford Ni I in certain cases, but in many other cases can lead instead to reduction of the macrocycle to generate an organic radical anion. Previous studies on the formation of tetraaza macrocyclic complexes of Ni I are discussed in terms of the competition between metal-centered and ligandcentered reduction. EPR results are particularly important in making the distinction between these two reduction processes, as formation of Ni I gives characteristic EPR spectra similar to those for Cu II , while ligand-centered reduction gives narrow EPR spectra at g = 2.00, typical of organic radicals. Even if metal-centered reduction occurs, the geometry of the resulting Ni I macrocyclic complex is highly variable and, as a result, the EPR spectral appearance is highly variable. In this case, the comparison is between the extremes of spectra typical for tetragonally distorted complexes (dx2-y2 1 ground state, which includes tetragonally distorted octahedral, square pyramidal and square planar geometries) and those for trigonal bipyramidal complexes (dz2 1 ground state). Previous work on Cu II was related to the situation for Ni I . The different types of EPR spectra for such systems are specifically discussed using previously unpublished examples of several tetraaza macrocyclic complexes of nickel, including F 430 and MCR itself.

show abstract

Porphyrin Dimers Linked by Conjugated Butadiyne Bridges: Preparations, Spectra, Voltammetry and Reductive Spectroelectrochemistry of {[M(OEP)](μ-C₄)[M(OEP)]}(M₂≡H₄, Co₂, Ni₂, Cu₂, Zn₂, Pd₂, Pt₂, Co/Ni, Ni

Arnold

Heath

James

1999

J. Porphyrins Phthalocyanines

View full text Add to dashboard Cite

A series of derivatives M 2 P 2 ( M 2 ≡ H 4, Co 2, Ni 2, Cu 2, Zn 2, Pd 2, Pt 2, Co / Ni , Ni / Cu , Ni / Zn ) of the ligand meso,meso′-bis(octaethylporphyrinyl)butadiyne has been prepared and characterized by 1 H NMR, FT Raman and visible absorption spectroscopies as well as by cyclic and a.c. voltammetry in CH 2 Cl 2 solution at 20 and −40 °C. The electronic spectra exhibit multiple Soret bands and the voltammetry reveals successive one-electron reductions indicating the accessibility of ‘mixed valence’ π-radical anions and π-dianions. Using in situ thin layer spectroelectrochemistry, the UV to near-IR spectra of [ M 2 P 2]1− and [ M 2 P 2]2− ( M as above) were recorded at ≤ −40 °C. Apart from the Co complexes (reduced at the metal ion), the bis(porphyrin) anions have spectra which include sharp, intense near-IR bands (ε = 50 000–200 000 M−1cm−1) at c. 4500 and 11 500 cm−1([ M 2 P 2]1−) and 9500 cm−1([ M 2 P 2]2−). An empirically constructed semiquantitative frontier orbital model explains the observed electronic absorption bands. Inter-porphyrin conjugation, mediated by the butadiyne bridge, is responsible for the Soret band multiplicity. The near-IR bands of the anions are assigned to long-axis polarized π → π* transitions within the newly occupied upper manifold of the two-porphyrin eight-orbital framework. The small comproportionation constants found for the diporphyrin monoanions contradict the usual assumption that electronically coupled dimers should have a large voltammetric separation between the first and second redox steps.

show abstract

Reactions of the nickel(I) octaethylisobacteriochlorin anion with alkyl halides

Cited by 65 publications

References 0 publications

Metal carbonyl anions as model metal-centered nucleophiles in aromatic and vinylic substitution reactions

Metal carbonyl anions as model metal-centered nucleophiles in aromatic and vinylic substitution reactions

Overview of ligand versus metal centered redox reactions in tetraaza macrocyclic complexes of nickel with a focus on electron paramagnetic resonance studies

Porphyrin Dimers Linked by Conjugated Butadiyne Bridges: Preparations, Spectra, Voltammetry and Reductive Spectroelectrochemistry of {[M(OEP)](μ-C₄)[M(OEP)]}(M₂≡H₄, Co₂, Ni₂, Cu₂, Zn₂, Pd₂, Pt₂, Co/Ni, Ni

Contact Info

Product

Resources

About

Reactions of the nickel(I) octaethylisobacteriochlorin anion with alkyl halides

Cited by 65 publications

References 0 publications

Metal carbonyl anions as model metal-centered nucleophiles in aromatic and vinylic substitution reactions

Metal carbonyl anions as model metal-centered nucleophiles in aromatic and vinylic substitution reactions

Overview of ligand versus metal centered redox reactions in tetraaza macrocyclic complexes of nickel with a focus on electron paramagnetic resonance studies

Porphyrin Dimers Linked by Conjugated Butadiyne Bridges: Preparations, Spectra, Voltammetry and Reductive Spectroelectrochemistry of {[M(OEP)](μ-C4)[M(OEP)]}(M2≡H4, Co2, Ni2, Cu2, Zn2, Pd2, Pt2, Co/Ni, Ni

Contact Info

Product

Resources

About

Porphyrin Dimers Linked by Conjugated Butadiyne Bridges: Preparations, Spectra, Voltammetry and Reductive Spectroelectrochemistry of {[M(OEP)](μ-C₄)[M(OEP)]}(M₂≡H₄, Co₂, Ni₂, Cu₂, Zn₂, Pd₂, Pt₂, Co/Ni, Ni