A mononuclear hydroperoxo complex and its significance in catalytic oxidation mechanisms

Bayston, James H.; Winfield, ME

doi:10.1016/0021-9517(64)90120-4

Cited by 30 publications

(3 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Unless otherwise stated, compounds used were purchased from Merck or Fluka and were of the highest available purity. K 3 [Co(CN) 5 OOH] was prepared according to the method of Bayston and Winfield . The dry compound shows little or no decomposition (as shown by the change in its UV spectrum) over a period of weeks if stored below 0 °C .…”

Section: Methodsmentioning

confidence: 99%

“…Complexes of transition metals with the hydroperoxo ligand, HO 2 - , occupy an unusual position in coordination chemistry. They have been prepared in many different ways: by protonation of peroxo complexes, − by insertion of dioxygen into metal−hydrogen bonds, , by hydrogen abstraction by metal dioxygen complexes, by reduction of superoxo complexes, or simply by the reaction of the metal ion with hydrogen peroxide. − Although the complexes have in general been well characterized, there is little structural information and even fewer data on their reactivity. Nevertheless, hydroperoxo complexes are frequently postulated as intermediates in reactions involving dioxygen or hydrogen peroxide, both in catalytic systems 10,11 and in biological systems. , We are thus confronted with a series of complexes which are synthetically accessible by a number of routes, are potentially of great importance as reactive intermediates, yet are poorly understood.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reactivity of the Coordinated Hydroperoxo Ligand

et al. 1996

View full text Add to dashboard Cite

The reactivity of the hydroperoxo complex [Co(CN)(5)OOH](3)(-) has been studied in aqueous solution. The complex undergoes acid-catalyzed aquation (k = 1.89(5) x 10(-)(2) s(-)(1), pK(a) = 5.21(4), T = 20 degrees C, I = 0.1 M). Assuming an I(d) mechanism, this allows the relative affinity for Co(III) to be deduced as H(2)O(2) < H(2)O < HO(2)(-) and implies H(2)O(2) to be a very weak ligand. At neutral pH the hydroperoxo complex effects efficient oxygen atom transfer to L-methionine to give an intermediate identified as [Co(CN)(5)(L-methionine S-oxide)](2)(-), which then dissociates to [Co(CN)(5)OH(2)](2)(-) and L-methionine S-oxide. The reaction is acid catalyzed and is proposed to take place via nucleophilic attack of sulfur on the proximal oxygen of the hydroperoxo ligand with concerted loss of water. The significance of these results for the interaction of hydrogen peroxide with labile metal ions is discussed.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reactivity of the Coordinated Hydroperoxo Ligand

et al. 1996

View full text Add to dashboard Cite

show abstract

“…Metal–dioxygen species such as metal–(hydro)peroxo [M–O 2 (H)] complexes have been invoked as important reactive intermediates for various oxidative reactions in biological systems. − For examples, numerous M–O 2 (H) complexes have been reported to conduct nucleophilic reactions, including aldehyde deformylation in biomimetic models. − Several M–O 2 (H) species have been documented to readily oxidize nitriles under mild conditions (Scheme ). − In a rhodium complex with tert -butyl isocyanide and triethylphosphine ligands, it was revealed that the rhodium(III)–hydroperoxo intermediate is responsible for the nitrile activation to afford a rhodium(III)–peroxyimidato species (step a) .…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Insights into Nitrile Activation by Cobalt(III)–Hydroperoxo Intermediates: The Influence of Ligand Basicity

Son,

Jeong,

Kim

et al. 2023

JACS Au

View full text Add to dashboard Cite

The versatile applications of nitrile have led to the widespread use of nitrile activation in the synthesis of pharmacologically and industrially valuable compounds. We reported the activation of nitriles using mononuclear cobalt(III)–hydroperoxo complexes, [CoIII(Me3-TPADP)(O2H)(RCN)]2+ [R = Me (2) and Ph (2 Ph)], to form cobalt(III)–peroxyimidato complexes, [CoIII(Me3-TPADP)(R–C(NH)O2)]2+ [R = Me (3) and Ph (3 Ph)]. The independence of the rate on the nitrile concentration and the positive Hammett value of 3.2(2) indicated that the reactions occur via an intramolecular nucleophilic attack of the hydroperoxide ligand to the coordinated nitrile carbon atom. In contrast, the previously reported cobalt(III)–hydroperoxo complex, [CoIII(TBDAP)(O2H)(CH3CN)]2+ (2 TBDAP), exhibited the deficiency of reactivity toward nitrile. The comparison of pK a values and redox potentials of 2 and 2 TBDAP showed that Me3-TPADP had a stronger ligand field strength than that of TBDAP. The density functional theory calculations for 2 and 2 TBDAP support that the strengthened ligand field in 2 is mainly due to the replacement of two tert-butyl amine donors in TBDAP with methyl groups in Me3-TPADP, resulting in the compression of the Co–Nax bond lengths. These results provide mechanistic evidence of nitrile activation by the cobalt(III)–hydroperoxo complex and indicate that the basicity dependent on the ligand framework contributes to the ability of nitrile activation.

show abstract

In the Formation of Hydrogen Peroxide and Hydroperoxo Species

Towl¹

1986

Inorganic Reactions and Methods

View full text Add to dashboard Cite

A mononuclear hydroperoxo complex and its significance in catalytic oxidation mechanisms

Cited by 30 publications

References 12 publications

Reactivity of the Coordinated Hydroperoxo Ligand

Reactivity of the Coordinated Hydroperoxo Ligand

Mechanistic Insights into Nitrile Activation by Cobalt(III)–Hydroperoxo Intermediates: The Influence of Ligand Basicity

In the Formation of Hydrogen Peroxide and Hydroperoxo Species

Contact Info

Product

Resources

About