Dioxygen Reactivity of Copper(I) Complexes with Tetradentate Tripodal Ligands Having Aliphatic Nitrogen Donors: Synthesis, Structures, and Properties of Peroxo and Superoxo Complexes

Komiyama, K.; Furutachi, Hideki; Nagatomo, Shigenori; Hashimoto, Akifumi; Hayashi, Hideki; Fujinami, Shuhei; Suzuki, Masatatsu; Kitagawa, Teizo

doi:10.1246/bcsj.77.59

Cited by 125 publications

(137 citation statements)

References 62 publications

(24 reference statements)

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“…Because no dioxygen adduct from oxygenation in solution of a tetra-N-functionalized cyclam copper(i) complex has been characterized, we have to rely on comparisons with other tetradendate systems described in the literature. In this regard, the aliphatic tetramine ligands derived from tris(2-aminoethyl)amine (tren) [7,77] or tris(2-pyridylmethyl)-A C H T U N G T R E N N U N G amine (tmpa) [5,78,79] can be considered as good models for the immobilized cyclams, although these are not macrocyclic derivatives. The average Cu···O distance is quite similar (1.86 AE 0.01 ) to the Cu À O bond lengths for copper dioxygen complexes characterized by X-ray crystallography.…”

Section: Resultsmentioning

confidence: 99%

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Exceptional Affinity of Nanostructured Organic–Inorganic Hybrid Materials towards Dioxygen: Confinement Effect of Copper Complexes

Brandès

David

Suspène

et al. 2007

Chemistry A European J

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We report the exceptional reactivity towards dioxygen of a nanostructured organic-inorganic hybrid material due to the confinement of copper cyclam within a silica matrix. The key step is the metalation reaction of the ligand, which can occur before or after xerogel formation through the sol-gel process. The incorporation of a Cu(II) center into the material after xerogel formation leads to a bridged Cu(I)/Cu(II) mixed-valence dinuclear species. This complex exhibits a very high affinity towards dioxygen, attributable to auto-organization of the active species in the solid. The remarkable properties of these copper complexes in the silica matrix demonstrate a high cooperative effect for O(2) adsorption; this is induced by close confinement of the two copper ions leading to end-on mu-eta(1):eta(1)-peroxodicopper(II) complexes. The anisotropic packing of the tetraazamacrocycle in a lamellar structure induces an exceptional reactivity of these copper complexes. We show for the first time that the organic-inorganic environment of copper complexes in a silica matrix fully model the protecting role of protein in metalloenzymes. For the first time an oxygenated dicopper(II) complex can be isolated in a stable form at room temperature, and the reduced Cu(2) (I,I) species can be regenerated after several adsorption-desorption cycles. These data also demonstrate that the coordination scheme and reactivity of the copper cyclams within the solid are quite different from that observed in solution.

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Section: Resultsmentioning

confidence: 99%

“…2 + peroxodicopper(II) with tmpa [78] or tren [77] tetradentate ligands. These structures have shown an end-on trans binding of the peroxide ion with a Cu···Cu separation of 4.36 for tmpa and 4.47 for functionalized tren.…”

Section: Resultsmentioning

confidence: 99%

Exceptional Affinity of Nanostructured Organic–Inorganic Hybrid Materials towards Dioxygen: Confinement Effect of Copper Complexes

Brandès

David

Suspène

et al. 2007

Chemistry A European J

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“…Such species have been found in the reactions of O 2 with heme proteins and models (6,7) as well as with one copper enzyme (8) and several synthetic copper and nickel complexes (9)(10)(11)(12)(13)(14)(15)(16). Such species have also been invoked in the mechanisms for nonheme iron enzymes, but only indirect evidence has been obtained to date (39)(40)(41).…”

Section: Discussionmentioning

confidence: 99%

“…Crystallographic evidence for an analogous formulation has also recently been reported for a copper enzyme peptidylglycine ␣-hydroxylating monooxygenase (PHM) (8). Furthermore, synthetic copper(I) and nickel(I) complexes react with O 2 to give rise to copper and nickel superoxo species (9)(10)(11)(12)(13)(14)(15)(16) 2 was prepared by using the same procedure in the presence of 10 eq of D 2 O. All manipulations with complex 1 and solutions thereof were carried out under inert atmosphere by using a glovebox filled with nitrogen.…”

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confidence: 99%

Intermediates in the oxygenation of a nonheme diiron(II) complex, including the first evidence for a bound superoxo species

Shan

Que

2005

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

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The reaction of [Fe2(-OH)2(6-Me3-TPA)2] 2؉ (1) [6-Me3-TPA, Tris(6-methyl-2-pyridylmethyl)amine] with O2 in CH2Cl2 at ؊80°C gives rise to two new intermediates, 2 and 3, before the formation of previously characterized [Fe2(O)(O2)(6-Me3-TPA)2] 2؉ (4) that allow the oxygenation reaction to be monitored one electron-transfer step at a time. Raman evidence assigns 2 and 3 as a diiron-superoxo species and a diiron-peroxo species, respectively. Intermediate 2 exhibits its (O-O) at 1,310 cm ؊1 with a ؊71-cm ؊1 18 O isotope shift. A doublet peak pattern for the 16 O 18 O isotopomer of 2 in mixedisotope Raman experiments strongly suggests that the superoxide ligand of 2 is bound end-on. This first example of a nonheme iron-superoxo intermediate exhibits the highest frequency (O-O) yet observed for a biomimetic metal-dioxygen adduct. The bound superoxide of 2, unlike the bound peroxide of 4, is readily reduced by 2,4-di-tert-butylphenol via a proton-coupled electron-transfer mechanism, emphasizing that metal-superoxo species may serve as oxidants in oxygen activation mechanisms of metalloenzymes. The discovery of intermediates 2 and 3 allows us to dissect the initial steps of dioxygen binding at a diiron center leading to its activation for substrate oxidation.nonheme diiron enzymes ͉ oxygen activation ͉ superoxo intermediate T he first step in the oxygen activation mechanisms of metalloenzymes is typically the binding of dioxygen, resulting in electron transfer from metal to O 2 to form a metal-superoxo species (1-5). This conversion is best exemplified by heme proteins and synthetic iron porphyrin complexes where there is strong crystallographic and spectroscopic evidence for an Fe III -( 1 -O 2•Ϫ ) formulation (6, 7). Crystallographic evidence for an analogous formulation has also recently been reported for a copper enzyme peptidylglycine ␣-hydroxylating monooxygenase (PHM) (8). Furthermore, synthetic copper(I) and nickel(I) complexes react with O 2 to give rise to copper and nickel superoxo species (9)(10)(11)(12)(13)(14)(15)(16) 2 was prepared by using the same procedure in the presence of 10 eq of D 2 O. All manipulations with complex 1 and solutions thereof were carried out under inert atmosphere by using a glovebox filled with nitrogen. Dichloromethane was distilled from CaH 2 under nitrogen. 2,4-di-tert-butylphenol (DTBP) was purchased from Aldrich and used as received. Saturated solutions of O 2 in CH 2 Cl 2 for the kinetic studies were prepared by bubbling the dried O 2 gas through the solvent for 10 min at room temperature. The concentration of O 2 in this saturated solution was accepted to be as reported in the literature (25) Sample Preparation. For UV-visible experiments, an anaerobic solution of 1⅐(OTf) 2 (3.3 mg) in dry CH 2 Cl 2 (3 ml) was introduced into a 1-cm-path-length cuvette and then cooled to 193 K in a Unisoku cryogenic cell holder attached to a HewlettPackard 8453A diode array spectrophotometer. O 2 gas was bubbled through the solution for 5 min, and the formation of 2 was complete within 1 h....

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“…Based on the almost perfect match between experiment and quantum chemical results for the O À O stretching frequencies we excluded the presence of a side-on coordination mode and we felt safe to assign a stable 1:1 end-on Cu-O 2 adduct, which is best described as an end-on superoxo-copper(II) species. [19] Yet, erroneous characterizations of 1:1 Cu-O 2 adduct complexes and recent discussions on the assignment of end-on superoxo-copper(II) complexes in the literature [19][20][21] made it clear that only a crystal structure of this complex would allow for the unambiguous characterization of such a 1:1 end-on Cu-O 2 adduct. [1][2][3] In spite of the observed stability of the Cu-O 2 adduct formed, numerous attempts to obtain crystals of this compound failed.…”

Section: Tren]mentioning

confidence: 99%

Crystallographic Characterization of a Synthetic 1:1 End‐On Copper Dioxygen Adduct Complex

et al. 2006

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No doubt: The high‐quality crystal structure of [Cu(TMG3tren)(O2)]SbF6 (see picture) presents the first unambiguous characterization of a bioinorganic compound in which a dioxygen molecule coordinates end‐on to a CuI ion. This species, which is best described as a superoxo copper(II) complex, serves as a model complex for initially formed Cu–O2 adducts present in a variety of active sites of copper enzymes.

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Dioxygen Reactivity of Copper(I) Complexes with Tetradentate Tripodal Ligands Having Aliphatic Nitrogen Donors: Synthesis, Structures, and Properties of Peroxo and Superoxo Complexes

Cited by 125 publications

References 62 publications

Exceptional Affinity of Nanostructured Organic–Inorganic Hybrid Materials towards Dioxygen: Confinement Effect of Copper Complexes

Exceptional Affinity of Nanostructured Organic–Inorganic Hybrid Materials towards Dioxygen: Confinement Effect of Copper Complexes

Intermediates in the oxygenation of a nonheme diiron(II) complex, including the first evidence for a bound superoxo species

Crystallographic Characterization of a Synthetic 1:1 End‐On Copper Dioxygen Adduct Complex

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