Mechanism of Oxidation of (Meso-5, 7, 7, 12, 14, 14-Hexamethyl-1, 4, 8, 11-Tetraazacyclotetradecane)Nickel(II) by H2O Free Radicals in Aqueous Solutions. A Pulse Radiolysis Study

Avraham Meshulam; Dan Meyerstein; Haim Cohen; Rudi Van Eldik

doi:10.1021/ic00037a031

Mechanism of Oxidation of (Meso-5, 7, 7, 12, 14, 14-Hexamethyl-1, 4, 8, 11-Tetraazacyclotetradecane)Nickel(II) by H₂O Free Radicals in Aqueous Solutions. A Pulse Radiolysis Study

Avraham Meshulam, Dan Meyerstein, Haim Cohen, Rudi Van Eldik

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Abstract

The title complex NiL²⁺ is oxidized in aqueous solutions in the pH range 3-7 in the presence of stabilizing anions X, X = HCO₂^-, SO₄^2-, and H₂PO₄^-, by HO₂^· free radicals to Ni^IIILX₂. The dependence of the rate of formation on [NiL²⁺] and X indicates that the H0₂_· radical reacts with a [NiL²⁺] complex in the ion pair [NiL²⁺, X], forming the final products. The volumes of activation of the oxidation processes were measured; an analysis of the data indicates that the ion pairs involved are contact ion pairs. The results indicate that in the presence of appropriate transition-metal complexes the superoxide free radical is a potent oxidizing agent and suggest that this might cause some of the aspects of its toxicity.

Original language	English
Pages (from-to)	2151-2156
Number of pages	6
Journal	Inorganic Chemistry
Volume	31
Issue number	11
DOIs	https://doi.org/10.1021/ic00037a031
State	Published - 1992
Externally published	Yes

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title = "Mechanism of Oxidation of (Meso-5, 7, 7, 12, 14, 14-Hexamethyl-1, 4, 8, 11-Tetraazacyclotetradecane)Nickel(II) by H2O Free Radicals in Aqueous Solutions. A Pulse Radiolysis Study",

abstract = "The title complex NiL2+ is oxidized in aqueous solutions in the pH range 3-7 in the presence of stabilizing anions X, X = HCO2-, SO42-, and H2PO4-, by HO2· free radicals to NiIIILX2. The dependence of the rate of formation on [NiL2+] and X indicates that the H02· radical reacts with a [NiL2+] complex in the ion pair [NiL2+, X], forming the final products. The volumes of activation of the oxidation processes were measured; an analysis of the data indicates that the ion pairs involved are contact ion pairs. The results indicate that in the presence of appropriate transition-metal complexes the superoxide free radical is a potent oxidizing agent and suggest that this might cause some of the aspects of its toxicity.",

author = "Avraham Meshulam and Dan Meyerstein and Haim Cohen and {Van Eldik}, Rudi",

year = "1992",

doi = "10.1021/ic00037a031",

language = "אנגלית",

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pages = "2151--2156",

journal = "Inorganic Chemistry",

issn = "0020-1669",

publisher = "American Chemical Society",

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T1 - Mechanism of Oxidation of (Meso-5, 7, 7, 12, 14, 14-Hexamethyl-1, 4, 8, 11-Tetraazacyclotetradecane)Nickel(II) by H2O Free Radicals in Aqueous Solutions. A Pulse Radiolysis Study

AU - Meshulam, Avraham

AU - Meyerstein, Dan

AU - Cohen, Haim

AU - Van Eldik, Rudi

PY - 1992

Y1 - 1992

N2 - The title complex NiL2+ is oxidized in aqueous solutions in the pH range 3-7 in the presence of stabilizing anions X, X = HCO2-, SO42-, and H2PO4-, by HO2· free radicals to NiIIILX2. The dependence of the rate of formation on [NiL2+] and X indicates that the H02· radical reacts with a [NiL2+] complex in the ion pair [NiL2+, X], forming the final products. The volumes of activation of the oxidation processes were measured; an analysis of the data indicates that the ion pairs involved are contact ion pairs. The results indicate that in the presence of appropriate transition-metal complexes the superoxide free radical is a potent oxidizing agent and suggest that this might cause some of the aspects of its toxicity.

AB - The title complex NiL2+ is oxidized in aqueous solutions in the pH range 3-7 in the presence of stabilizing anions X, X = HCO2-, SO42-, and H2PO4-, by HO2· free radicals to NiIIILX2. The dependence of the rate of formation on [NiL2+] and X indicates that the H02· radical reacts with a [NiL2+] complex in the ion pair [NiL2+, X], forming the final products. The volumes of activation of the oxidation processes were measured; an analysis of the data indicates that the ion pairs involved are contact ion pairs. The results indicate that in the presence of appropriate transition-metal complexes the superoxide free radical is a potent oxidizing agent and suggest that this might cause some of the aspects of its toxicity.

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JO - Inorganic Chemistry

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Mechanism of Oxidation of (Meso-5, 7, 7, 12, 14, 14-Hexamethyl-1, 4, 8, 11-Tetraazacyclotetradecane)Nickel(II) by H₂O Free Radicals in Aqueous Solutions. A Pulse Radiolysis Study

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