Cu(I)/O2 Chemistry Using a β-Diketiminate Supporting Ligand Derived from N,N-Dimethylhydrazine: A [Cu3O2]3+ Complex with Novel Reactivity

Gupta, Aalo K.; Tolman, William B.

doi:10.1021/ic202214c

Cited by 32 publications

(44 citation statements)

References 57 publications

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“…The complexes of 115 and 116 react with 2,4-di-tert-butylphenol to yield the radical coupling product 3,3',5,5'-tetratert-butyl-2,2'-biphenol, consistent with electrophilic character and H-atom abstraction reactivity similar to related bis(μ-oxo)dicopper(III) complexes [262]. In contrast, the complex supported by 117 was unreactive with phenols or DHA, but oxidized PPh 3 to O¼PPh 3 and was quenched by CO 2 [375]. Apparently, the charge and strong electron donating properties of 117 perturb the core so as to induce 'nucleophilic' reactivity similar to that identified for (trans-1,2-peroxo)dicopper complexes [264].…”

Section: Tricopper Models Of Multicopper Active Sites In Enzymessupporting

confidence: 54%

“…In studies of dioxygen activation by more than two Cu(I) sites that target possible intermediates, tricopper species often comprise the bis(μ-oxo)tricopper(II,II,III) core (114, Figure 53). Initially prepared and fully characterized upon low temperature oxygenation of Cu(I) complexes of ligands 115 [371][372][373], such cores have since been reported using several other N-donors (115)(116)(117)(118) [374][375][376]. Complex 119 was prepared by low temperature oxygenation of a tricopper(I) complex of ligand 118.…”

Section: Tricopper Models Of Multicopper Active Sites In Enzymesmentioning

confidence: 99%

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Transition Metal Complexes and the Activation of Dioxygen

Yee

Tolman

2014

Metal Ions in Life Sciences

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In order to address how diverse metalloprotein active sites, in particular those containing iron and copper, guide O₂binding and activation processes to perform diverse functions, studies of synthetic models of the active sites have been performed. These studies have led to deep, fundamental chemical insights into how O₂coordinates to mono- and multinuclear Fe and Cu centers and is reduced to superoxo, peroxo, hydroperoxo, and, after O-O bond scission, oxo species relevant to proposed intermediates in catalysis. Recent advances in understanding the various factors that influence the course of O₂activation by Fe and Cu complexes are surveyed, with an emphasis on evaluating the structure, bonding, and reactivity of intermediates involved. The discussion is guided by an overarching mechanistic paradigm, with differences in detail due to the involvement of disparate metal ions, nuclearities, geometries, and supporting ligands providing a rich tapestry of reaction pathways by which O₂is activated at Fe and Cu sites.

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Section: Tricopper Models Of Multicopper Active Sites In Enzymessupporting

confidence: 54%

Section: Tricopper Models Of Multicopper Active Sites In Enzymesmentioning

confidence: 99%

Transition Metal Complexes and the Activation of Dioxygen

Yee

Tolman

2014

Metal Ions in Life Sciences

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“…Di-{Cu 2 À O 2 } and trinuclear {Cu 3 À O 2 } intermediates [3,26] have previously been observed with N-donor ligands, but the observation of both with the same ligand is extremely rare. [27] UV/Vis spectroscopy of {Cu n ÀO 2 } species: Exposing colorless to pale-yellow solutions of complexes 1-3 in THF to dry O 2 at À80 8C caused a relatively rapid color change to purple (1), dark blue (2), and dark red-brown (3). As indicated in Table 2, all Cu I complexes exhibit a single strong absorption band in the UV region, which is likely to be an OÀCu ligand-to-metal charge-transfer (LMCT) band.…”

Section: Resultsmentioning

confidence: 99%

K⋅⋅⋅F/O Interactions Bridge Copper(I) Fluorinated Alkoxide Complexes and Facilitate Dioxygen Activation

Lum

Tahsini

Golen

et al. 2013

Chemistry A European J

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Seven E[Cu(OR)2] copper(I) complexes (E = K(+), {K(18C6)}(+) (18C6 = [18]crown-6), or Ph4P(+); R = C4F9, CPhMe(F)2, and CMeMe(F)2) have been prepared and their reactivity with O2 studied. The K[Cu(OR)2] species react with O2 in a copper-concentration-dependent manner such that 2:1 and 3:1 Cu/O2 adducts are observed manometrically at -78 °C. Analogous reactivity with O2 is not observed with the {K(18C6)}(+) or Ph4P(+) derivatives. Solution conductivity data demonstrate that these K[Cu(OR)2] complexes do not behave as 1:1 electrolytes in solution. The K(+) ions induce aggregation of multiple [Cu(OR)2](-) units through K⋅⋅⋅F/O interactions and thereby effect irreversible O2 reduction by multiple Cu centers. Bond valence analyses for the potassium cations confirm the dominance of the fluorine interactions in the coordination spheres of K(+) ions. Intramolecular hydroxylation of ligand aryl and alkyl C-H bonds is observed. Nucleophilic reactivity with CO2 is observed for the oxygenated Cu complexes and a Cu(II) carbonate has been isolated and characterized.

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“…While EXAFS modeling corroborate the metrical parameters of the X-ray structure, the more intense Cu(II) pre-edge feature at 8979 eV masks any potential lower intensity Cu(III) feature at 8981 eV [31,32]. A limited number of other T complexes formed with non-sterically demanding, bidentate ligation are known, primarily characterized through their optical spectra [42,43,93,94]. …”

Section: Monooxygenase Reactivity Of O Speciesmentioning

confidence: 97%

High-valent copper in biomimetic and biological oxidations

2016

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A long-standing debate in the Cu-O2 field has revolved around the relevance of the Cu(III) oxidation state in biological redox processes. The proposal of Cu(III) in biology is generally challenged as no spectroscopic or structural evidence exists currently for its presence. The reaction of synthetic Cu(I) complexes with O2 at low temperature in aprotic solvents provides the opportunity to investigate and define the chemical landscape of Cu-O2 species at a small molecule level of detail; eight different types are characterized structurally, three of which contain at least one Cu(III) center. Simple imidazole or histamine ligands are competent in these oxygenation reactions to form Cu(III) complexes. The combination of synthetic structural and reactivity data suggests (i) that Cu(I) should be considered as either a one or two electron reductant reacting with O2, (ii) that Cu(III) reduction potentials of these formed complexes are modest and well within the limits of a protein matrix and (iii) that primary amine and imidazole ligands are surprisingly good at stabilizing Cu(III) centers. These Cu(III) complexes are efficient oxidants for hydroxylating phenolate substrates with reaction hallmarks similar to that performed in biological systems. The remarkable ligation similarity of the synthetic and biological systems makes it difficult to continue to exclude Cu(III) from biological discussions.

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Cu(I)/O₂ Chemistry Using a β-Diketiminate Supporting Ligand Derived from N,N-Dimethylhydrazine: A [Cu₃O₂]³⁺ Complex with Novel Reactivity

Cited by 32 publications

References 57 publications

Transition Metal Complexes and the Activation of Dioxygen

Transition Metal Complexes and the Activation of Dioxygen

K⋅⋅⋅F/O Interactions Bridge Copper(I) Fluorinated Alkoxide Complexes and Facilitate Dioxygen Activation

High-valent copper in biomimetic and biological oxidations

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