Complexation of a nickel(III) macrocyclic complex by sulfate ion. A pulse radiolytic study

Cohen, Haim; Kirschenbaum, Louis J.; Zeigerson, E.; Jaacobi, Moshe; Fuchs, E; Ginzburg, Gregory; Meyerstein, Dan

doi:10.1021/ic50200a026

Cited by 36 publications

(26 citation statements)

References 6 publications

(7 reference statements)

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“…The rates in the presence of trifluoroacetate, shown in Table 3, are, as expected, lower than in the presence of acid alone because of change of redox potential by ligation (15,17,18 radical by a mechanism similar to that previously proposed for coordinated bromide (17).…”

Section: Organic Productssupporting

confidence: 81%

“…In light of the recent work on the base catalysed decomposition of Ni(II1) macrocycles (16)(17)(18)(19)(20) the results of the present work can best be explained by the following general mechani~m.~ 'The proton could also be lost from the nitrogen next to the carbon containing 2 methyl groups to give another isomer of 3. Likewise the radical in 4 could, and very likely is, also on the other nitrogen.…”

Section: Discussionmentioning

confidence: 68%

“…It is possible that the acid itself is merely a source of trifluoroacetate ion which is coordinating to the Ni(II1) and slowing the rate by lowering the redox potential (15,17,18). Thus the changes in spectra shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Later several Ni(II1) macrocyclic complexes, including 2, were generated by pulse radiolysis and their decomposition studied (17)(18)(19)(20). Although there was some disagreement as to the actual identity of all species detected, an acid inhibition term in the decomposition of the Ni(II1) complex was noted and attributed to the equilibrium given by [2], where N-H represents an amino group on the complex (17,20).…”

Section: +Imentioning

confidence: 99%

“…Complexing in the axial positions with groups such as SO,2-, OH-, and Br-stabilized the Ni(II1) complex (15,17,18). When Br-is the ligating group decomposition occurs by formation of Br.…”

Section: +Imentioning

confidence: 99%

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Kinetics and mechanism of the oxidation of cyclohexanone by a nickel(III) macrocyclic ligand complex in CH₃CN

Welsh¹,

Otutakowski²,

Henry³

1981

Can. J. Chem.

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. Can. J. Chem. 59,697 (1981). CF3C02H is not due to complexation of trifluoroacetate but is a real acid inhibition term. The isotope effect, kHlkD using 2,2,6,6-tetradeuterocyclohexanone as substrate, was 3.2. The main product found in greater than 100% yield based on Ni(II1) was the non-oxidative product, 2(cyclohexen-1-yl)cyclohexanone, which must have been formed in a radical chain reaction. A mechanism involving deprotonation of one of the coordinated nitrogens followed by rearrangement to a Ni(I1) ligand rad~cal intermediate is proposed. The ligand radical extracts a hydrogen from cyclohexanone to give [Ni(II)meso- [14]ane] and a cyclohexanone radical which initiates a radical chain reaction to give the observed dimeric product. Support for the mechanism is provided by recent stud~es of the base catalyzed decomposition of Ni(II1) complexes in aqueous and non-aqueous solvents.In the presence of CF3C02Na, the Ni(II1) complex decomposes rap~dly even in the absence of cyclohexanone. This is believed to occur via trifluoroacetoxy radicals, a mechanism which has analogy in other systems. que le facteur d'inhibition dans le CF3C02H n'est pas dii a la complexation du trifluoroacetate, mais qu'il est un facteur reel d'inhibition acide. L'effet isotopique kH/kD mesurC sur la tetradeutiro-2,2,6,6 cyclohexanone est de 3,2. Le produit principal obtenu avec un rendement superieur a 100% si I'on se base sur le Ni(II1) est un produit qui ne provient pas d'une oxydation, soit la (cyclohexene-1 y1)-2 cyclohexanone, qui a dii se former au cours d'une reaction radicalaire en chaine. On propose un mecanisme qui fait intervenir la deprotonation d'un des atomes d'azote coordonnes suivie de la transposition en un intermediaire ligand radicalaire du Ni(I1). Le ligand radicalaire arrache un atome d'hydrogkne de la cyclohexanone et conduit au [Ni(II)mCsoane [l4]] et au radical cyclohexanone qui initie la reaction radicalaire en chaine conduisant aux produits dimeres. Ce mecanisme est confirme par des etudes recentes sur la decomposition catalysie par une base de complexes de Ni(II1) dans des solvants aqueux et non aqueux.En presence de CF3C02Na, le complexe de Ni(II1) se decompose rapidement mime en I'absence de cyclohexanone. On pense que cette decomposition a lieu par I'intermtdiaire de radicaux fluoroacttoxy, un mecanisme que I'on retrouve dans d'autres systemes.[Traduit par le journal]

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Section: Organic Productssupporting

confidence: 81%

Section: Discussionmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Section: +Imentioning

confidence: 99%

“…Complexing in the axial positions with groups such as SO,2-, OH-, and Br-stabilized the Ni(II1) complex (15,17,18). When Br-is the ligating group decomposition occurs by formation of Br.…”

Section: +Imentioning

confidence: 99%

See 3 more Smart Citations

Kinetics and mechanism of the oxidation of cyclohexanone by a nickel(III) macrocyclic ligand complex in CH₃CN

Welsh¹,

Otutakowski²,

Henry³

1981

Can. J. Chem.

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Nickel: Inorganic & Coordination Chemistry

Collinson

Schröder

2005

Encyclopedia of Inorganic Chemistry

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The general features and coordination chemistry of Ni 0 to Ni IV and complexation to cyanide, N‐, P‐, O‐, S‐, and halide‐donor ligands are detailed. The reactivity of Ni II complexes in the template synthesis of macrocycles and for the oligomerization and polymerization of alkenes are highlighted. The stabilization of radical Ni I and Ni III centers is related to the associated ligand types and metal‐ion stereochemistries. The supramolecular chemistry of Ni II includes the formation of aggregates, framework polymers, and receptors. The structures of a number of Ni‐containing enzymes have been elucidated and the formation of low‐molecular weight complex mimics is discussed.

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With Nickel

Hoffman¹

1986

Inorganic Reactions and Methods

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Complexation of a nickel(III) macrocyclic complex by sulfate ion. A pulse radiolytic study

Cited by 36 publications

References 6 publications

Kinetics and mechanism of the oxidation of cyclohexanone by a nickel(III) macrocyclic ligand complex in CH₃CN

Kinetics and mechanism of the oxidation of cyclohexanone by a nickel(III) macrocyclic ligand complex in CH₃CN

Nickel: Inorganic & Coordination Chemistry

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Complexation of a nickel(III) macrocyclic complex by sulfate ion. A pulse radiolytic study

Cited by 36 publications

References 6 publications

Kinetics and mechanism of the oxidation of cyclohexanone by a nickel(III) macrocyclic ligand complex in CH3CN

Kinetics and mechanism of the oxidation of cyclohexanone by a nickel(III) macrocyclic ligand complex in CH3CN

Nickel: Inorganic & Coordination Chemistry

With Nickel

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Kinetics and mechanism of the oxidation of cyclohexanone by a nickel(III) macrocyclic ligand complex in CH₃CN

Kinetics and mechanism of the oxidation of cyclohexanone by a nickel(III) macrocyclic ligand complex in CH₃CN