μ-Peroxodicobalt(III) complexes containing aromatic ligands

Ortego, J. Dale; Seymour, Mark

doi:10.1016/s0277-5387(00)81063-3

Cited by 20 publications

(5 citation statements)

References 17 publications

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“…While much effort has been directed on the effect of the size of the chain linked to the pyridyl ring, the influence of functional groups that induce cross-conjugation have attracted limited attention. For instance, in 2,2‘-dipyridyl ketone (pyCOpy = dpk) and in 2,2‘-dipyridylamine (pyNHpy = dpamH) the bridging groups not only induce cross-conjugation but also render the ligands reactive. , The ligand reactivity, in conjunction with the tendency of copper(II) to achieve coordination numbers exceeding 4, may occasionally lead to misinterpretation of the spectra. The effects of ligand reactivity on the spectra of coordination compounds are better understood when a series of similarly structured compounds become available and this is accomplished by employing coligands differing in substituents far away from the coordination site.…”

Section: Introductionmentioning

confidence: 99%

Influence of the Bridging Group of Cross-Conjugated Nitrogenous Bases on the Spectra and Structure of Solvatochromic Mixed-Ligand Copper(II) Chelates Containing β-Ketoenols

1998

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The concomitant reaction of copper(II) with a heterocyclic nitrogenous cross-conjugated Lewis base (2,2′-dipyridyl ketone, dpk, or 2,2′-dipyridylamine, dpamH) and the anion of a 2-substituted 1,3-dione, β -, e.g. X-acac -(X ) H, Me, Cl, CN, NO 2 ) affords mixed-ligand chelates. The composition and structure of the chelates depend on the group linking the pyridyl rings. Chelation renders the 2,2′-dipyridyl ketone susceptible to nucleophilic attack by protic molecules. It also depends on the group attached to the β-dionato moiety since electron attracting substituents facilitate ligation of a water molecule when the 2,2′-dipyridylamine is present. Spectroscopic observations indicated square pyramidal or distorted tetragonal stereochemistries of the ensuing mixed-ligand chelates with the carbonyl oxygens and the pyridyl nitrogens forming the basal plane. Confirmation was acquired by X-ray structure determination of representative chelates. The compound [Cu(NC-acac)dpamH(H 2 O) OClO 3 ] crystallizes in the Pnma space group with Z ) 8 (i.e. four molecules per cell), a ) 17.996(1) Å, b ) 13.972(1) Å, c ) 7.801(1) Å. The copper atom is 2.401(3) Å from the oxygen of the water molecule and 2.60(2) Å from an oxygen atom of the ClO 4group. The chelate [Cu(NC-acac)dpC(OH)OCH 3 (OClO 3 ), resulting from the addition of methanol to the carbon atom bridging the pyridyl rings, crystallizes in the P2 1 /n space group with a ) 10.661-(1) Å, b ) 14.987(2) Å, c ) 13.963(1) Å, β ) 110.57(3)°, Z ) 4. An oxygen of the ClO 4group is in apical position, and it is 2.634(8) Å from the copper atom. The etheric oxygen is distanced 2.615(2) Å from the copper atom, and the O-Cu-O angle of these weak bonds is only 154.4(2)°. In these chelates the nitrogenous bases adopt the boat conformation with the pyridyl rings forming dihedral angles of approximately 33°.

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Section: Introductionmentioning

confidence: 99%

Influence of the Bridging Group of Cross-Conjugated Nitrogenous Bases on the Spectra and Structure of Solvatochromic Mixed-Ligand Copper(II) Chelates Containing β-Ketoenols

1998

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“…XRD analysis of crystals grown from a high concentrated Co{i‐N 4 } acetonitrile solution at room temperature after exposure to air confirmed formation of a peroxo‐bridged dimer Co 2 (O 2 ){i‐N 4 } 2 (Figure 5C) as an additional diamagnetic Co−O 2 intermediate. The bridging μ 2 ‐peroxo binding mode is commonly observed in Cu containing enzymes known for their O 2 activation capability, [68,69] as well as in biomimetic synthetic Cu and Co complexes [25,26,70–72] . In the herein received structure of Co 2 (O 2 ){i‐N 4 } 2 each Co III atom is coordinated in‐plane by the four N‐donor atoms of one macrocyclic ligand and axially by the bound μ ‐peroxo and acetonitrile ligands.…”

Section: Resultsmentioning

confidence: 88%

“…The bridging μ 2 -peroxo binding mode is commonly observed in Cu containing enzymes known for their O 2 activation capability, [68,69] as well as in biomimetic synthetic Cu and Co complexes. [25,26,[70][71][72] In the herein received structure of Co 2 (O 2 ){i-N 4 } 2 each Co III atom is coordinated in-plane by the four N-donor atoms of one macrocyclic ligand and axially by the bound μ-peroxo and acetonitrile ligands. Similar coordination behavior was postulated for the cyclam-based Co complex and structurally proven for a sulfur-containing cyclam-analog.…”

Section: Orr Capability and Reactivity Towards Omentioning

confidence: 99%

How Ligand Geometry Affects the Reactivity of Co(II) Cyclam Complexes

Iffland‐Mühlhaus,

Battistella,

Siegmund

et al. 2023

Eur J Inorg Chem

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Cobalt complexes are extensively studied as bioinspired models for non‐heme oxygenases as they facilitate both the stabilization and characterization of metal‐oxygen intermediates. As an analog to the well‐known Co(cyclam) complex Co{N4} (cyclam = 1,4,8,11‐tetraazacyclotetradecane), the CoII complex Co{i‑N4} with the isomeric isocyclam ligand (isocyclam = 1,4,7,11‐tetraazacyclotetradecane) was synthesized and characterized. Despite the identical N4 donor set of both complexes, Co{i‐N4} enables the 2e‾/2H+ reduction of O2 with a lower overpotential (ηeff of 385 mV vs. 540 mV for Co{N4}), albeit with a diminished turnover frequency. Characterization of the intermediates formed upon O2 activation of Co{i‐N4} reveals a structurally identified stable µ‐peroxo CoIII dimer as the main product. A superoxo CoIII species is also formed as a minor product, as indicated by EPR spectroscopy. In further reactivity studies, the electrophilicity of these in situ generated Co‐O2 species was demonstrated by the oxidation of the O‐H bond of TEMPO‐H (2,2,6,6‐tetramethylpiperidin‐1‐ol) via a H atom abstraction process. Unlike the known Co(cyclam), Co{i‐N4} can be employed in oxygen atom transfer reactions oxidizing triphenylphosphine to the corresponding phosphine oxide highlighting the impact of geometrical modifications of the ligand while preserving the ring size and donor atom set on the reactivity of biomimetic oxygen activating complexes.

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“…haemoglobin, haemerythrin, haemocyanin and their model compounds. 1 Many biological reactions involving dioxygen are very fast with synthetic caged dioxygen carriers. Cobalt(II) complexes of polyamines, amino acids, and dipeptide ligands containing dicobalt, μ-peroxo or, μ-superoxo-bridged derivatives have been studied extensively, because of their applicability to biochemical systems.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and structural characterization of a novel peroxo bridged dinuclear cobalt(III) complex of succinimide showing three varieties of hydrogen bonding interactions

Taş

Büyükgüngör

2009

J Chem Sci

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The reaction of aqueous cobaltous nitrate hexahydrate with the anion of succinimide (sucH) in the presence of excess ethylenediamine (en) in air results in the formation of a dinuclear complex μ-peroxo-bis[bis(ethylenediamine)succinimidato-cobalt(III)] dinitrate dihydrate, 1, in good yield. Compound 1 was characterized by elemental analysis, IR, visible spectra and magnetic susceptibility studies. The explosive nature of [Co(en) 2 (suc)(μ-O 2 )Co(en) 2 (suc)](NO 3 ) 2 ⋅2H 2 O, 1, precluded its thermal characterization. Compound 1 crystallises in the monoclinic space group P2 1 /c and a half of the molecule, constitutes its asymmetric unit. In the centrosymmetric dinuclear complex 1, two Co(III) centres are linked by a planar peroxide bridge. Each cobalt atom is surrounded by four nitrogen atoms of ethylenediamine ligands, a nitrogen atom of succinimidato anion and an oxygen atom of peroxo bridge resulting in a slightly distorted {CoN 5 O} octahedron. Due to steric hindrance between the two Co(III) centres, the peroxide bridge is planar with a Co-O-O-Co torsion angle of 180°. The dinuclear complex cation, the nitrate anion and the lattice water are involved in three varieties of H-bonding interactions namely N-H⋅⋅⋅O, O-H⋅⋅⋅O and C-H⋅⋅⋅O.

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μ-Peroxodicobalt(III) complexes containing aromatic ligands

Cited by 20 publications

References 17 publications

Influence of the Bridging Group of Cross-Conjugated Nitrogenous Bases on the Spectra and Structure of Solvatochromic Mixed-Ligand Copper(II) Chelates Containing β-Ketoenols

Influence of the Bridging Group of Cross-Conjugated Nitrogenous Bases on the Spectra and Structure of Solvatochromic Mixed-Ligand Copper(II) Chelates Containing β-Ketoenols

How Ligand Geometry Affects the Reactivity of Co(II) Cyclam Complexes

Synthesis and structural characterization of a novel peroxo bridged dinuclear cobalt(III) complex of succinimide showing three varieties of hydrogen bonding interactions

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