Sulfur-alkylation-initiated Cp∗Ru thiyl radicals

Shin, Richard; Sim, Hui Shan; Goh, Lai Yoong; Webster, Richard D.

doi:10.1016/j.jorganchem.2007.03.018

Cited by 6 publications

(3 citation statements)

References 37 publications

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“…Air oxidation of metal–thiolates can proceed through multiple steps including one- or two-electron events that are ligand- or metal-centered. Two-electron oxidations involve O-atom transfer, leading to high-valent metal oxo complexes , or metal-coordinated sulfur–oxygenates − with relevance to cysteine dioxygenase, , nitrile hydratase, ,,− and thiocyanate hydrolase. ,,, One-electron oxidations yield oxidized metal ions or thiyl radicals, − which may yield disulfide if not stabilized.…”

Section: Introductionmentioning

confidence: 99%

Metal-Stabilized Thiyl Radicals as Scaffolds for Reversible Alkene Addition via C–S Bond Formation/Cleavage

2011

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The one-electron oxidation of metal thiolates results in an increased oxidation state of the metal ion or the formation of a sulfur-based, thiyl radical in limiting extremes. For complexes with highly covalent M-S bonds, the unpaired electron may be delocalized over the metal and the sulfur, yielding a metal-stabilized thiyl radical. Oxidation of the metal thiolate precursors [Ru(DPPBT)(3)](-), [Ru-1](-), and Re(DPPBT)(3), Re-1 (DPPBT = diphenylphosphinobenzenethiolate), generates metal-stabilized thiyl radicals that react with alkenes to yield dithioether-metal products. Alkene addition to [Ru-1](+) and [Re-1](+) is symmetry-allowed due to the meridional arrangement of the DPPBT chelates. Combined bulk electrolysis and cyclic voltammetry experiments reveal the addition of alkenes to [Ru-1](+) as an irreversible process with experimentally determined rate constants ranging from 4.6(5) × 10(7) M(-1) s(-1) for electron-rich alkenes to 2.7(2) × 10(4) M(-1) s(-1) for electron-poor alkenes. Rate constants for cyclic alkenes range from 4(2) × 10(7) to 2.9(3) × 10(3) M(-1) s(-1). Chemical oxidation of [Ru-1](-) by ferrocenium hexafluorophosphate (FcPF(6)) in the presence of m-methylstyrene or p-methylstyrene yields the dithioether complexes [Ru-1·m-methylstyrene](+) and [Ru-1·p-methylstyrene](+), respectively. Each complex was crystallized and the structure determined by single-crystal X-ray diffraction. (31)P NMR of the samples reveals a major and minor product, each displaying a second-order spectrum. The oxidized intermediate [Re-1](+) binds alkenes reversibly with equilibrium binding constants that vary with the complex charge from 1.9 × 10(-11) M(-1) for n = 0 to 4.0 M(-1) for n = +1 to 2.5 × 10(9) M(-1) for n = +2. The three binding regimes are separated by 240 mV. Crystalline samples of [Re-1·C(2)H(4)](2+) are obtained upon chemical oxidation of Re-1 with silver hexafluorophosphate (AgPF(6)) in the presence of ethylene. Strategies for the addition of alkenes to other metal-stabilized thiyl radicals are suggested.

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Section: Introductionmentioning

confidence: 99%

Metal-Stabilized Thiyl Radicals as Scaffolds for Reversible Alkene Addition via C–S Bond Formation/Cleavage

2011

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“…These studies had revealed interesting reactivity features involving the acyclic S3 dithiolato ligand, eg. (i) ring closure across the S-Ru-S open 'jaw' with a,u-dibromoalkanes, transforming IeIII (Scheme 2) [38], or with metal fragments to produce di-to tetra-nuclear derivatives [42e46] and (ii) protonation and alkylation [47,48]. It was observed that the inherent electronic differences between I and II have a marked influence on the manner in which the h 3 -tpdt ligand functions as a dithiolate ligand in these reactions [49].…”

Section: Introductionmentioning

confidence: 99%

New thioether–dithiolate complexes of Cp∗Ir and some reactivity features

Goh

Pullarkat

2012

Journal of Organometallic Chemistry

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“…The Ru1ÀS1 (2.401(1) ) and the Ru1À N1 bond (2.159(2) ) in the neutralf orm 5 are shortened to 2.327(2) a nd 2.067 (7) , respectively,i n5 + .C onsistently,t he Ru1ÀP1 bond length has increased from2 .271(1) i n5 to 2.334(2) i n5 + ,r eflecting the loss of p-basicity of the Ru unit resultingfrom the oxidation. The structural data, in comparison with related thiolate complexes of Ru II[20] and Ru III [21] as well as amide and imine coordinations at Ru II[22] ,s trongly support an oxidation process of Ru II to Ru III during the conversion of 5 to 5 + .T aking these observations and the EPR spectroscopice vidence into account, the charged epletion at the Wc enter causedb yt he oxidation can preferentially be attributedt o ar edox induced change of the conjugation, which is accommodated by ag raduala lteration of the resonance structure from F to E (Scheme 3). Indeed, ac hange in the bond orders of the bridging ligand by oxidation is reflected in ad ecrease of the coupledC ÀC/CÀNb onds tretches (n as = 1529 cm À1 for 5 and 1465 cm À1 for 5 + ; n s = 1258 cm À1 for 5 and 1245cm À1 for 5 + ).…”

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confidence: 99%

Minimalistic Ditopic Ligands: An α‐S,N‐Donor‐Substituted Alkyne as Effective Intermetallic Conjugation Linker

Rüger

Timmermann

Villinger

et al. 2016

Chemistry A European J

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The capability of donor-substituted alkynes to link different metal ions in a side-on carbon donor-chelate coordination mode is extended from the donor centers S and P to the second period element N. The complex [Tp'W(CO)2 {η(2) -C2 (S)(NHBn)}] (Tp'=hydrido-tris(3,5-dimethylpyrazolyl)borate, Bn=benzyl) bearing a terminal sulfur atom and a secondary amine substituent is accessible by a metal-template synthesis. Subsequent deprotonation allowed the formation of remarkably stable heterobimetallic complexes with the [(η(5) -C5 H5 )Ru(PPh3 )] and the [Ir(ppy)2 ] moiety. Electrochemical and spectroscopic investigations (cyclic voltammetry, IR, UV/Vis, luminescence, EPR), as well as DFT calculations, and X-ray structure determinations of the W-Ru complex in two oxidation states reveal a strong metal-metal coupling but also a limited delocalization of excited states.

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Sulfur-alkylation-initiated Cp∗Ru thiyl radicals

Cited by 6 publications

References 37 publications

Metal-Stabilized Thiyl Radicals as Scaffolds for Reversible Alkene Addition via C–S Bond Formation/Cleavage

Metal-Stabilized Thiyl Radicals as Scaffolds for Reversible Alkene Addition via C–S Bond Formation/Cleavage

New thioether–dithiolate complexes of Cp∗Ir and some reactivity features

Minimalistic Ditopic Ligands: An α‐S,N‐Donor‐Substituted Alkyne as Effective Intermetallic Conjugation Linker

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