Peroxo-, Oxo-, and Hydroxo-Bridged Dicopper Complexes:  Observation of Exogenous Hydrocarbon Substrate Oxidation

Obias, Honorio V.; Lin, Yin; Murthy, Narasimha N.; Pidcock, Elna; Solomon, Edward I.; Ralle, Martina; Blackburn, Ninian J.; Neuhold, Yorck-Michael; Zuberbühler, Andreas D.; Karlin, Kenneth D.

doi:10.1021/ja981878h

Cited by 197 publications

(224 citation statements)

References 22 publications

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“…[25,31,115Ϫ121] Copper complexes incorporating L 16 (Scheme 7; R ϭ Me, phenyl) provide important insight into these reactions. [31,118,119] The above results are corroborated by investigations on tridentate ligands carried out in this laboratory. Copper(I) and copper(II) complexes of Me 5 dien (1,1,4,7,7-pentamethyldiethylethylenetriamine; Scheme 7) have previously been structurally characterized.…”

Section: Bridging Ligands Derived From Tren and Derivativessupporting

confidence: 71%

“…A mixture of these two species was also observed in solution. [31] Very recently, it has been shown that introduction of two 6-methylpyridyl groups into the tmpa ligand (substituted tmpa, R 1 ϭ H, R 2 , R 3 ϭ Me; Scheme 2) prevents the formation of trans-µ-1,2-peroxo-bridged dicopper(II) species in a trigonal-bipyramidal structure, probably due to the steric requirements of the two 6-methylpyridyl groups. Instead, formation of a brown bis(µ-oxo)dicopper(III) complex, [Cu 2 (O) 2 (Me 2 -tmpa) 2 ](PF 6 ) 2 ·(CH 3 ) 2 CO, is observed, the crystal structure of which has been reported.…”

Section: Structurally Characterized Copper Peroxo Superoxo and Oxo mentioning

confidence: 99%

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Reactivity of Copper(I) Complexes Towards Dioxygen

Schindler

2000

Eur. J. Inorg. Chem.

256

189

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Efforts to model the reactions of copper enzymes with dioxygen with low molecular weight complexes have been quite successful during recent years. Guided by Nature, intriguing model systems for the active sites of such proteins have been developed. In the course of these investigations, it has been discovered that a whole variety of copper−dioxygen adducts form when simple copper(I) complexes are oxidized with dioxygen. The course of these reactions depends on the temperature, the ligands present, and the solvent. The effects of these parameters (especially the effect of ligand modification) on the reactivity of copper(I) complexes towards dioxygen are discussed in detail in this review.

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Section: Bridging Ligands Derived From Tren and Derivativessupporting

confidence: 71%

Section: Structurally Characterized Copper Peroxo Superoxo and Oxo mentioning

confidence: 99%

Reactivity of Copper(I) Complexes Towards Dioxygen

Schindler

2000

Eur. J. Inorg. Chem.

256

189

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“…Similar spectroscopic features have been described for the copper(I) complexes of related bis[(2-pyrid-2-yl)ethyl]amine ligands after low-temperature oxygenation [25,26] and are characteristic for a Cu [20] compound 2 starts to decompose after 8 min of O 2 uptake at 195 K, as evident from a decrease in the intensity of the absorption bands at 364, 430, 510, and 650 nm. The decomposition of 2 results in the formation of m-hydroxy benzaldehyde after benzylic hydroxylation with subsequent N-dealkylation (Scheme 2).…”

supporting

confidence: 71%

Benzylic Ligand Hydroxylation Starting from a Dicopper μ‐η²:η² Peroxo Intermediate: Dramatic Acceleration of the Reaction by Hydrogen‐Atom Donors

2011

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Radicals in directed pathways: The μ‐η2:η2 peroxo CuII2 intermediate 1 shows a much faster benzylic ligand hydroxylation than systems without phenol. This novel reactivity can be further accelerated by addition of external H‐atom donors such as TEMPO‐H. The results imply initial H‐atom transfer leading to the formation of phenoxyl radicals. A highly reactive copper oxyl intermediate is then formed, which inserts oxygen into the benzylic CH bond.

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“…Computational studies on Cu-ZSM-5 have surveyed the possible stabilization of several binuclear Cu sites in Cu-ZSM-5, including CuOO 2 OCu and CuOOOCu cores (7,23), but without spectroscopic data to discriminate among them, no assignment of the active site structure could be made. The presence of a bent CuOOOCu core in synthetic model complexes has been proposed (24)(25)(26), but to date, no such complex has been unambiguously defined. As a result, the data reported in the present study are the first to definitively characterize a mono-oxygen bridged binuclear Cu site in any system.…”

Section: Resultsmentioning

confidence: 99%

A [Cu ₂ O] ²⁺ core in Cu-ZSM-5, the active site in the oxidation of methane to methanol

Woertink

Smeets

Groothaert

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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609

653

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Driven by the depletion of crude oil, the direct oxidation of methane to methanol has been of considerable interest. Promising low-temperature activity of an oxygen-activated zeolite, Cu-ZSM-5, has recently been reported in this selective oxidation and the active site in this reaction correlates with an absorption feature at 22,700 cm ؊1 . In the present study, this absorption band is used to selectively resonance enhance Raman vibrations of this active site. 18 O2 labeling experiments allow definitive assignment of the observed vibrations and exclude all previously characterized copper-oxygen species for the active site. In combination with DFT and normal coordinate analysis calculations, the oxygen activated Cu core is uniquely defined as a bent mono-( -oxo)dicupric site. Spectroscopically validated electronic structure calculations show polarization of the low-lying singly-occupied molecular orbital of the [Cu 2O] 2؉ core, which is directed into the zeolite channel, upon approach of CH 4. This induces significant oxyl character into the bridging O atom leading to a low transition state energy consistent with experiment and explains why the bent mono-( -oxo)dicupric core is highly activated for H atom abstraction from CH 4. The oxygen intermediate of Cu-ZSM-5 is now the most well defined species active in the methane monooxygenase reaction. density functional theory ͉ dicopper(II)-oxo ͉ oxygen activation ͉ resonance Raman spectroscopy ͉ zeolite

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Peroxo-, Oxo-, and Hydroxo-Bridged Dicopper Complexes: Observation of Exogenous Hydrocarbon Substrate Oxidation

Cited by 197 publications

References 22 publications

Reactivity of Copper(I) Complexes Towards Dioxygen

Reactivity of Copper(I) Complexes Towards Dioxygen

Benzylic Ligand Hydroxylation Starting from a Dicopper μ‐η²:η² Peroxo Intermediate: Dramatic Acceleration of the Reaction by Hydrogen‐Atom Donors

A [Cu ₂ O] ²⁺ core in Cu-ZSM-5, the active site in the oxidation of methane to methanol

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Peroxo-, Oxo-, and Hydroxo-Bridged Dicopper Complexes: Observation of Exogenous Hydrocarbon Substrate Oxidation

Cited by 197 publications

References 22 publications

Reactivity of Copper(I) Complexes Towards Dioxygen

Reactivity of Copper(I) Complexes Towards Dioxygen

Benzylic Ligand Hydroxylation Starting from a Dicopper μ‐η2:η2 Peroxo Intermediate: Dramatic Acceleration of the Reaction by Hydrogen‐Atom Donors

A [Cu 2 O] 2+ core in Cu-ZSM-5, the active site in the oxidation of methane to methanol

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Benzylic Ligand Hydroxylation Starting from a Dicopper μ‐η²:η² Peroxo Intermediate: Dramatic Acceleration of the Reaction by Hydrogen‐Atom Donors

A [Cu ₂ O] ²⁺ core in Cu-ZSM-5, the active site in the oxidation of methane to methanol