Oxidation of Thioanisoles and Methyl Phenyl Sulfoxides by Oxo(phosphine)ruthenium(IV) Complexes

John Henry Acquaye; James G. Muller; Kenneth J. Takeuchi

doi:10.1021/ic00054a008

Oxidation of Thioanisoles and Methyl Phenyl Sulfoxides by Oxo(phosphine)ruthenium(IV) Complexes

John Henry Acquaye
, James G. Muller
, Kenneth J. Takeuchi

Chemistry

SUNY Buffalo

Research output: Contribution to journal › Article › peer-review

64 Scopus citations

Abstract

The oxo(phosphine)ruthenium(IV) complexes [Ru(bpy)₂(O)PR₃](ClO₄)2 (bpy = 2,2′-bipyridine; PR₃ = P(C₆H₅)₃, P(p-C₆H₄OCH₃)₃, P(p-C₆H₄CH₃)3, P(p-C₆H₄F)₃₎ P(C₆H₅)(p-C₆H₄CF₃)₂, P(p-C₆H₄CF₃)₃) cleanly oxidize sulfides to sulfoxides and in separate experiments oxidize sulfoxides to sulfones. The substrate oxidations are second order overall, first order in substrate concentration and first order in ruthenium concentration. Through the use of para-substituted thioanisoles and para-substituted methyl phenyl sulfoxides, linear free energy relationship analyses of the kinetics of substrate oxidations by [Ru(bpy)₂(O)P(C₆H₅)₃](ClO₄)₂ were conducted. For the oxidation of sulfides to sulfoxides, an excellent correlation (R² = 0.99) was obtained between log (k_x/k_H) and the σ-values for the substituents of para-substituted thioanisoles (ρ = −1.56). For the oxidation of sulfoxides to sulfones, a good correlation (R² = 0.98) was obtained between log (k_x/k_H) and the σ⁺ values for the substituents of para-substituted methyl phenyl sulfoxides (ρ = −0.42). In addition, the kinetic isotope effect for the oxidation of thioanisole and methyl-d₃ phenyl sulfide produced k_H/k_D = 1.14, and the oxidation of methyl phenyl sulfoxide and methyl-d₃ phenyl sulfoxide resulted in an inverse isotope effect of k_H/k_D = 0.64. Finally, through the use of [Ru(bpy)₂(O)PR₃]-(ClO₄)₂ complexes, Hammett-type analyses of the kinetics of thioanisole oxidation and methyl phenyl sulfoxide oxidation by the [Ru(bpy)₂(O)PR₃](ClO₄)₂ complexes afford a different approach in analysis of the mechanism of sulfide and sulfoxide oxidation. Hammett correlations of log (k_x/k_H) versus Σσ (where σ is the Hammett substituent constant for each of the para substituents on the triphenylphosphine ligands) also show linear relationships The slopes of these plots gave ρ = 0.49 (R² = 0.99) for the oxidation of thioanisole and ρ = 0.37 (R² = 0.99) for the oxidation of methyl phenyl sulfoxide by the [Ru(bpy)₂(O)PR₃] (ClO₄)₂ complexes. The results of all our experiments suggest that the rate-determining step in the oxidation of thioanisole by [Ru(bpy)₂(O)P(C₆H₅)₃](ClO₄)₂ involve primarily single-electron transfer, whereas the rate-determining step of the oxidation of methyl phenyl sulfoxide involves primarily an S_N2 mechanism.

Original language	English
Pages (from-to)	160-165
Number of pages	6
Journal	Inorganic Chemistry
Volume	32
Issue number	2
DOIs	https://doi.org/10.1021/ic00054a008
State	Published - 1993

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@article{8a5676ec748a4616a04f51a47b1c5986,

title = "Oxidation of Thioanisoles and Methyl Phenyl Sulfoxides by Oxo(phosphine)ruthenium(IV) Complexes",

abstract = "The oxo(phosphine)ruthenium(IV) complexes [Ru(bpy)2(O)PR3](ClO4)2 (bpy = 2,2′-bipyridine; PR3 = P(C6H5)3, P(p-C6H4OCH3)3, P(p-C6H4CH3)3, P(p-C6H4F)3) P(C6H5)(p-C6H4CF3)2, P(p-C6H4CF3)3) cleanly oxidize sulfides to sulfoxides and in separate experiments oxidize sulfoxides to sulfones. The substrate oxidations are second order overall, first order in substrate concentration and first order in ruthenium concentration. Through the use of para-substituted thioanisoles and para-substituted methyl phenyl sulfoxides, linear free energy relationship analyses of the kinetics of substrate oxidations by [Ru(bpy)2(O)P(C6H5)3](ClO4)2 were conducted. For the oxidation of sulfides to sulfoxides, an excellent correlation (R2 = 0.99) was obtained between log (kx/kH) and the σ-values for the substituents of para-substituted thioanisoles (ρ = −1.56). For the oxidation of sulfoxides to sulfones, a good correlation (R2 = 0.98) was obtained between log (kx/kH) and the σ+ values for the substituents of para-substituted methyl phenyl sulfoxides (ρ = −0.42). In addition, the kinetic isotope effect for the oxidation of thioanisole and methyl-d3 phenyl sulfide produced kH/kD = 1.14, and the oxidation of methyl phenyl sulfoxide and methyl-d3 phenyl sulfoxide resulted in an inverse isotope effect of kH/kD = 0.64. Finally, through the use of [Ru(bpy)2(O)PR3]-(ClO4)2 complexes, Hammett-type analyses of the kinetics of thioanisole oxidation and methyl phenyl sulfoxide oxidation by the [Ru(bpy)2(O)PR3](ClO4)2 complexes afford a different approach in analysis of the mechanism of sulfide and sulfoxide oxidation. Hammett correlations of log (kx/kH) versus Σσ (where σ is the Hammett substituent constant for each of the para substituents on the triphenylphosphine ligands) also show linear relationships The slopes of these plots gave ρ = 0.49 (R2 = 0.99) for the oxidation of thioanisole and ρ = 0.37 (R2 = 0.99) for the oxidation of methyl phenyl sulfoxide by the [Ru(bpy)2(O)PR3] (ClO4)2 complexes. The results of all our experiments suggest that the rate-determining step in the oxidation of thioanisole by [Ru(bpy)2(O)P(C6H5)3](ClO4)2 involve primarily single-electron transfer, whereas the rate-determining step of the oxidation of methyl phenyl sulfoxide involves primarily an SN2 mechanism.",

author = "Acquaye, \{John Henry\} and Muller, \{James G.\} and Takeuchi, \{Kenneth J.\}",

year = "1993",

doi = "10.1021/ic00054a008",

language = "English",

volume = "32",

pages = "160--165",

journal = "Inorganic Chemistry",

issn = "0020-1669",

number = "2",

}

TY - JOUR

T1 - Oxidation of Thioanisoles and Methyl Phenyl Sulfoxides by Oxo(phosphine)ruthenium(IV) Complexes

AU - Acquaye, John Henry

AU - Muller, James G.

AU - Takeuchi, Kenneth J.

PY - 1993

Y1 - 1993

N2 - The oxo(phosphine)ruthenium(IV) complexes [Ru(bpy)2(O)PR3](ClO4)2 (bpy = 2,2′-bipyridine; PR3 = P(C6H5)3, P(p-C6H4OCH3)3, P(p-C6H4CH3)3, P(p-C6H4F)3) P(C6H5)(p-C6H4CF3)2, P(p-C6H4CF3)3) cleanly oxidize sulfides to sulfoxides and in separate experiments oxidize sulfoxides to sulfones. The substrate oxidations are second order overall, first order in substrate concentration and first order in ruthenium concentration. Through the use of para-substituted thioanisoles and para-substituted methyl phenyl sulfoxides, linear free energy relationship analyses of the kinetics of substrate oxidations by [Ru(bpy)2(O)P(C6H5)3](ClO4)2 were conducted. For the oxidation of sulfides to sulfoxides, an excellent correlation (R2 = 0.99) was obtained between log (kx/kH) and the σ-values for the substituents of para-substituted thioanisoles (ρ = −1.56). For the oxidation of sulfoxides to sulfones, a good correlation (R2 = 0.98) was obtained between log (kx/kH) and the σ+ values for the substituents of para-substituted methyl phenyl sulfoxides (ρ = −0.42). In addition, the kinetic isotope effect for the oxidation of thioanisole and methyl-d3 phenyl sulfide produced kH/kD = 1.14, and the oxidation of methyl phenyl sulfoxide and methyl-d3 phenyl sulfoxide resulted in an inverse isotope effect of kH/kD = 0.64. Finally, through the use of [Ru(bpy)2(O)PR3]-(ClO4)2 complexes, Hammett-type analyses of the kinetics of thioanisole oxidation and methyl phenyl sulfoxide oxidation by the [Ru(bpy)2(O)PR3](ClO4)2 complexes afford a different approach in analysis of the mechanism of sulfide and sulfoxide oxidation. Hammett correlations of log (kx/kH) versus Σσ (where σ is the Hammett substituent constant for each of the para substituents on the triphenylphosphine ligands) also show linear relationships The slopes of these plots gave ρ = 0.49 (R2 = 0.99) for the oxidation of thioanisole and ρ = 0.37 (R2 = 0.99) for the oxidation of methyl phenyl sulfoxide by the [Ru(bpy)2(O)PR3] (ClO4)2 complexes. The results of all our experiments suggest that the rate-determining step in the oxidation of thioanisole by [Ru(bpy)2(O)P(C6H5)3](ClO4)2 involve primarily single-electron transfer, whereas the rate-determining step of the oxidation of methyl phenyl sulfoxide involves primarily an SN2 mechanism.

AB - The oxo(phosphine)ruthenium(IV) complexes [Ru(bpy)2(O)PR3](ClO4)2 (bpy = 2,2′-bipyridine; PR3 = P(C6H5)3, P(p-C6H4OCH3)3, P(p-C6H4CH3)3, P(p-C6H4F)3) P(C6H5)(p-C6H4CF3)2, P(p-C6H4CF3)3) cleanly oxidize sulfides to sulfoxides and in separate experiments oxidize sulfoxides to sulfones. The substrate oxidations are second order overall, first order in substrate concentration and first order in ruthenium concentration. Through the use of para-substituted thioanisoles and para-substituted methyl phenyl sulfoxides, linear free energy relationship analyses of the kinetics of substrate oxidations by [Ru(bpy)2(O)P(C6H5)3](ClO4)2 were conducted. For the oxidation of sulfides to sulfoxides, an excellent correlation (R2 = 0.99) was obtained between log (kx/kH) and the σ-values for the substituents of para-substituted thioanisoles (ρ = −1.56). For the oxidation of sulfoxides to sulfones, a good correlation (R2 = 0.98) was obtained between log (kx/kH) and the σ+ values for the substituents of para-substituted methyl phenyl sulfoxides (ρ = −0.42). In addition, the kinetic isotope effect for the oxidation of thioanisole and methyl-d3 phenyl sulfide produced kH/kD = 1.14, and the oxidation of methyl phenyl sulfoxide and methyl-d3 phenyl sulfoxide resulted in an inverse isotope effect of kH/kD = 0.64. Finally, through the use of [Ru(bpy)2(O)PR3]-(ClO4)2 complexes, Hammett-type analyses of the kinetics of thioanisole oxidation and methyl phenyl sulfoxide oxidation by the [Ru(bpy)2(O)PR3](ClO4)2 complexes afford a different approach in analysis of the mechanism of sulfide and sulfoxide oxidation. Hammett correlations of log (kx/kH) versus Σσ (where σ is the Hammett substituent constant for each of the para substituents on the triphenylphosphine ligands) also show linear relationships The slopes of these plots gave ρ = 0.49 (R2 = 0.99) for the oxidation of thioanisole and ρ = 0.37 (R2 = 0.99) for the oxidation of methyl phenyl sulfoxide by the [Ru(bpy)2(O)PR3] (ClO4)2 complexes. The results of all our experiments suggest that the rate-determining step in the oxidation of thioanisole by [Ru(bpy)2(O)P(C6H5)3](ClO4)2 involve primarily single-electron transfer, whereas the rate-determining step of the oxidation of methyl phenyl sulfoxide involves primarily an SN2 mechanism.

UR - https://www.scopus.com/pages/publications/0001059402

U2 - 10.1021/ic00054a008

DO - 10.1021/ic00054a008

M3 - Article

AN - SCOPUS:0001059402

SN - 0020-1669

VL - 32

SP - 160

EP - 165

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 2

ER -

Oxidation of Thioanisoles and Methyl Phenyl Sulfoxides by Oxo(phosphine)ruthenium(IV) Complexes

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