Catalytic cycle of a divanadium complex with salen ligands in O2 reduction: Two-electron redox process of the dinuclear center (salen = N,N'-ethylenebis(salicylideneamine))

K. Yamamoto, Kenichi Oyaizu, E. Tsuchida

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    Abstract

    In an attempt to provide confirmation for the postulated mechanism of O2 reduction in vanadium-mediated oxidative polymerization of diphenyl disulfide, a series of divanadium complexes containing salen ligand (salen = N,N'-ethylenebis(salicylideneamine)) were prepared, characterized, and subjected to reactivity studies toward dioxygen. A divanadium (III, IV) complex, [(salen)VOV(salen)][I3] (II), was yielded both by treatments of solutions of [(salen)VOV(salen)][BF4]2 (I) in acetonitrile with excess tetrabutylammonium iodide and by electroreduction of I followed by anion exchange with tetrabutylammonium triiodide. The complex II was characterized by a near-infrared absorption at 7.2 x 103 cm-1 (ε = 60.1 M-1 cm-1 in acetonitrile) assigned to an intervalence transfer band. A crystallographically determined V(III)-V(IV) distance of 3.569(4) Å is consonant with the classification of II as a weakly coupled Type II mixed-valence vanadium (α = 3.0 x 10-2). Oxidation of the cation [(salen)VOV(salen)]+ with O2 in dichloromethane yielded spontaneously the deep blue, mixed valent, divanadium (IV, V) species [(salen)VOVO(salen)]+ which was structurally characterized both as its triiodide (III) and perchlorate (IV) salts. Crystal data for III: triclinic space group Pl̄ (no. 2), a = 14.973(2) Å, b = 19.481(2) Å, c = 14.168(2) Å, α = 107.00 (1)°, β = 115.56(1)°, γ = 80.35(1)°, V = 3561.3(9) Å3, Z = 4, D(calc) 1.953 g/cm3, μ (MoKα) = 31.74 cm-1, final R = 0.057 and R(w) = 0.065. Crystal data for IV: triclinic space group P1̄ (no. 2), a = 11.923(3) Å, b = 14.25(1) Å, c = 11.368(7) Å, α = 112.92(5)°, β = 92.76(4)°, γ = 99.13(4)°, V = 1743(1) Å3, Z = 2, D(calc) = 1.537 g/cm3, μ (CuKα) = 57.69 cm-1, final R = 0.042 and R(W) = 0.061. The complexes III and IV were deoxygenated in strongly acidic nonaqueous media to produce [(salen)VOV(salen)]3+ as a high-valent complex whose reversible two-electron redox couple (VOV3+/VOV+) at 0.44V vs Ag/AgCl has been confirmed. Its ability to serve as a two-electron oxidant provided a unique model of a multielectron redox cycle in oxidative polymerization.

    Original languageEnglish
    Pages (from-to)12665-12672
    Number of pages8
    JournalJournal of the American Chemical Society
    Volume118
    Issue number50
    DOIs
    Publication statusPublished - 1996

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    Acetonitrile
    Vanadium
    Oxidation-Reduction
    Ligands
    Polymerization
    Electrons
    Crystals
    Dichloromethane
    Infrared absorption
    Oxidants
    Ion exchange
    Negative ions
    Positive ions
    Salts
    Oxidation
    disalicylaldehyde ethylenediamine
    Methylene Chloride
    Anions
    Cations
    Oxygen

    ASJC Scopus subject areas

    • Chemistry(all)

    Cite this

    @article{932512b5ac5041878c19832118268ad7,
    title = "Catalytic cycle of a divanadium complex with salen ligands in O2 reduction: Two-electron redox process of the dinuclear center (salen = N,N'-ethylenebis(salicylideneamine))",
    abstract = "In an attempt to provide confirmation for the postulated mechanism of O2 reduction in vanadium-mediated oxidative polymerization of diphenyl disulfide, a series of divanadium complexes containing salen ligand (salen = N,N'-ethylenebis(salicylideneamine)) were prepared, characterized, and subjected to reactivity studies toward dioxygen. A divanadium (III, IV) complex, [(salen)VOV(salen)][I3] (II), was yielded both by treatments of solutions of [(salen)VOV(salen)][BF4]2 (I) in acetonitrile with excess tetrabutylammonium iodide and by electroreduction of I followed by anion exchange with tetrabutylammonium triiodide. The complex II was characterized by a near-infrared absorption at 7.2 x 103 cm-1 (ε = 60.1 M-1 cm-1 in acetonitrile) assigned to an intervalence transfer band. A crystallographically determined V(III)-V(IV) distance of 3.569(4) {\AA} is consonant with the classification of II as a weakly coupled Type II mixed-valence vanadium (α = 3.0 x 10-2). Oxidation of the cation [(salen)VOV(salen)]+ with O2 in dichloromethane yielded spontaneously the deep blue, mixed valent, divanadium (IV, V) species [(salen)VOVO(salen)]+ which was structurally characterized both as its triiodide (III) and perchlorate (IV) salts. Crystal data for III: triclinic space group Pl̄ (no. 2), a = 14.973(2) {\AA}, b = 19.481(2) {\AA}, c = 14.168(2) {\AA}, α = 107.00 (1)°, β = 115.56(1)°, γ = 80.35(1)°, V = 3561.3(9) {\AA}3, Z = 4, D(calc) 1.953 g/cm3, μ (MoKα) = 31.74 cm-1, final R = 0.057 and R(w) = 0.065. Crystal data for IV: triclinic space group P1̄ (no. 2), a = 11.923(3) {\AA}, b = 14.25(1) {\AA}, c = 11.368(7) {\AA}, α = 112.92(5)°, β = 92.76(4)°, γ = 99.13(4)°, V = 1743(1) {\AA}3, Z = 2, D(calc) = 1.537 g/cm3, μ (CuKα) = 57.69 cm-1, final R = 0.042 and R(W) = 0.061. The complexes III and IV were deoxygenated in strongly acidic nonaqueous media to produce [(salen)VOV(salen)]3+ as a high-valent complex whose reversible two-electron redox couple (VOV3+/VOV+) at 0.44V vs Ag/AgCl has been confirmed. Its ability to serve as a two-electron oxidant provided a unique model of a multielectron redox cycle in oxidative polymerization.",
    author = "K. Yamamoto and Kenichi Oyaizu and E. Tsuchida",
    year = "1996",
    doi = "10.1021/ja9617799",
    language = "English",
    volume = "118",
    pages = "12665--12672",
    journal = "Journal of the American Chemical Society",
    issn = "0002-7863",
    publisher = "American Chemical Society",
    number = "50",

    }

    TY - JOUR

    T1 - Catalytic cycle of a divanadium complex with salen ligands in O2 reduction

    T2 - Two-electron redox process of the dinuclear center (salen = N,N'-ethylenebis(salicylideneamine))

    AU - Yamamoto, K.

    AU - Oyaizu, Kenichi

    AU - Tsuchida, E.

    PY - 1996

    Y1 - 1996

    N2 - In an attempt to provide confirmation for the postulated mechanism of O2 reduction in vanadium-mediated oxidative polymerization of diphenyl disulfide, a series of divanadium complexes containing salen ligand (salen = N,N'-ethylenebis(salicylideneamine)) were prepared, characterized, and subjected to reactivity studies toward dioxygen. A divanadium (III, IV) complex, [(salen)VOV(salen)][I3] (II), was yielded both by treatments of solutions of [(salen)VOV(salen)][BF4]2 (I) in acetonitrile with excess tetrabutylammonium iodide and by electroreduction of I followed by anion exchange with tetrabutylammonium triiodide. The complex II was characterized by a near-infrared absorption at 7.2 x 103 cm-1 (ε = 60.1 M-1 cm-1 in acetonitrile) assigned to an intervalence transfer band. A crystallographically determined V(III)-V(IV) distance of 3.569(4) Å is consonant with the classification of II as a weakly coupled Type II mixed-valence vanadium (α = 3.0 x 10-2). Oxidation of the cation [(salen)VOV(salen)]+ with O2 in dichloromethane yielded spontaneously the deep blue, mixed valent, divanadium (IV, V) species [(salen)VOVO(salen)]+ which was structurally characterized both as its triiodide (III) and perchlorate (IV) salts. Crystal data for III: triclinic space group Pl̄ (no. 2), a = 14.973(2) Å, b = 19.481(2) Å, c = 14.168(2) Å, α = 107.00 (1)°, β = 115.56(1)°, γ = 80.35(1)°, V = 3561.3(9) Å3, Z = 4, D(calc) 1.953 g/cm3, μ (MoKα) = 31.74 cm-1, final R = 0.057 and R(w) = 0.065. Crystal data for IV: triclinic space group P1̄ (no. 2), a = 11.923(3) Å, b = 14.25(1) Å, c = 11.368(7) Å, α = 112.92(5)°, β = 92.76(4)°, γ = 99.13(4)°, V = 1743(1) Å3, Z = 2, D(calc) = 1.537 g/cm3, μ (CuKα) = 57.69 cm-1, final R = 0.042 and R(W) = 0.061. The complexes III and IV were deoxygenated in strongly acidic nonaqueous media to produce [(salen)VOV(salen)]3+ as a high-valent complex whose reversible two-electron redox couple (VOV3+/VOV+) at 0.44V vs Ag/AgCl has been confirmed. Its ability to serve as a two-electron oxidant provided a unique model of a multielectron redox cycle in oxidative polymerization.

    AB - In an attempt to provide confirmation for the postulated mechanism of O2 reduction in vanadium-mediated oxidative polymerization of diphenyl disulfide, a series of divanadium complexes containing salen ligand (salen = N,N'-ethylenebis(salicylideneamine)) were prepared, characterized, and subjected to reactivity studies toward dioxygen. A divanadium (III, IV) complex, [(salen)VOV(salen)][I3] (II), was yielded both by treatments of solutions of [(salen)VOV(salen)][BF4]2 (I) in acetonitrile with excess tetrabutylammonium iodide and by electroreduction of I followed by anion exchange with tetrabutylammonium triiodide. The complex II was characterized by a near-infrared absorption at 7.2 x 103 cm-1 (ε = 60.1 M-1 cm-1 in acetonitrile) assigned to an intervalence transfer band. A crystallographically determined V(III)-V(IV) distance of 3.569(4) Å is consonant with the classification of II as a weakly coupled Type II mixed-valence vanadium (α = 3.0 x 10-2). Oxidation of the cation [(salen)VOV(salen)]+ with O2 in dichloromethane yielded spontaneously the deep blue, mixed valent, divanadium (IV, V) species [(salen)VOVO(salen)]+ which was structurally characterized both as its triiodide (III) and perchlorate (IV) salts. Crystal data for III: triclinic space group Pl̄ (no. 2), a = 14.973(2) Å, b = 19.481(2) Å, c = 14.168(2) Å, α = 107.00 (1)°, β = 115.56(1)°, γ = 80.35(1)°, V = 3561.3(9) Å3, Z = 4, D(calc) 1.953 g/cm3, μ (MoKα) = 31.74 cm-1, final R = 0.057 and R(w) = 0.065. Crystal data for IV: triclinic space group P1̄ (no. 2), a = 11.923(3) Å, b = 14.25(1) Å, c = 11.368(7) Å, α = 112.92(5)°, β = 92.76(4)°, γ = 99.13(4)°, V = 1743(1) Å3, Z = 2, D(calc) = 1.537 g/cm3, μ (CuKα) = 57.69 cm-1, final R = 0.042 and R(W) = 0.061. The complexes III and IV were deoxygenated in strongly acidic nonaqueous media to produce [(salen)VOV(salen)]3+ as a high-valent complex whose reversible two-electron redox couple (VOV3+/VOV+) at 0.44V vs Ag/AgCl has been confirmed. Its ability to serve as a two-electron oxidant provided a unique model of a multielectron redox cycle in oxidative polymerization.

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