Electron photodetachment from mercaptyl anions (RS-). Electron affinities of mercaptyl radicals and the sulfur-hydrogen bond strength in mercaptans

Janousek, Bruce K.; Reed, Kenneth J.; Brauman, John I.

doi:10.1021/ja00529a040

Cited by 82 publications

(49 citation statements)

References 7 publications

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“…The reported experimental D(S‐H) values are larger than D(CH 3 S‐H) by 0.7‐1.2 kcal mol −1 with the error limits of 2 kcal mol −1 (Refs. 34–36) and < E av > = 33.9 kcal mol −1 was assigned to the major channel of both reactions. The spectra 18 from reactions (4) and (5) were refitted using the new model bands and the distributions were analyzed neglecting channel (b).…”

Section: Resultsmentioning

confidence: 99%

Reactions of OH and OD radicals with simple thiols and sulfides studied by infrared chemiluminescence of isotopic water products: Reaction OH + CH₃SH revisited

Butkovskaya

Setser

2021

Int J of Chemical Kinetics

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Vibrational excitation of the H2O, HOD, and D2O product molecules from the reactions of OH and OD radicals with CH3SH, CH3C(O)SH, (CH3)3CSH, H2S, and CH3SCH3 was determined by modeling the infrared emission spectra using a renovated and extended set of model spectroscopic bands. Using the deuterated reactant, CH3SD, it was possible to separate spectra of abstraction from C‐ and S‐sites, which allowed measurement of branching fractions and kinetic isotope effects for individual channels. For the OH + CH3SH reaction, branching fractions of 0.13 ± 0.03 (C─H) and 0.87 ± 0.03 (S─H) were obtained. The vibrational energy released to water from abstraction of H‐atoms from the C─H and S─H sites of the reactant molecules is described. The results reported in this paper take precedence over an earlier study of CH3SH. The vibrational energy partitioning between the stretch and bend modes of water molecules from the reactions of the thiols and related reactions of H2S and CH3SCH3 are discussed. The mechanism for the OH + CH3SSCH3 reaction was confirmed to be addition followed mainly by decomposition to CH3SH and CH3SO.

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Section: Resultsmentioning

confidence: 99%

Reactions of OH and OD radicals with simple thiols and sulfides studied by infrared chemiluminescence of isotopic water products: Reaction OH + CH₃SH revisited

Butkovskaya

Setser

2021

Int J of Chemical Kinetics

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“…The reaction enthalpy –Δ H o 0 = D 0 (HO‐H) – D 0 (R‐H) was obtained from the bond dissociation energies (BDE) of sulfur compounds and D 0 (HO‐H) = 118.08 ± 0.03 kcal mol −1 . The D 0 (CH 3 C(O)S‐H) and D 0 ((CH 3 ) 3 CS‐H) obtained by electrochemical methods are given in Table . The C–H BDEs in the methyl groups of these compounds are not known, but are expected to be at least 5–6 kcal mol −1 higher than those for S–H (as, for example ,94 kcal mol −1 in CH 3 SH or 95.3 in CH 3 COOH,); hence, abstraction from the methyl groups is a minor channel and was ignored.…”

Section: Resultsmentioning

confidence: 99%

Rate constants and vibrational distributions for water‐forming reactions of OH and OD radicals with thioacetic acid, 1,2‐ethanedithiol and tert‐butanethiol

Butkovskaya

Setser

2019

Int J of Chemical Kinetics

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Reactions of OH and OD radicals with CH3C(O)SH, HSCH2CH2SH, and (CH3)3CSH were studied at 298 K in a fast‐flow reactor by infrared emission spectroscopy of the water product molecules. The rate constants (1.3 ± 0.2) × 10−11 cm3 molecule−1 s−1 for the OD + CH3C(O)SH reaction and (3.8 ± 0.7) × 10−11 cm3 molecule−1 s−1 for the OD + HSCH2CH2SH reaction were determined by comparing the HOD emission intensity to that from the OD reaction with H2S, and this is the first measurement of these rate constants. In the same manner, using the OD + (C2H5)2S reference reaction, the rate constant for the OD + (CH3)3CSH reaction was estimated to be (3.6 ± 0.7) × 10−11 cm3 molecule−1 s−1. Vibrational distributions of the H2O and HOD molecules from the title reactions are typical for H‐atom abstraction reactions by OH radicals with release of about 50% of the available energy as vibrational energy to the water molecule in a 2:1 ratio of stretch and bend modes.

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“…The ferryl basicity of compound II that leads to the Fe IV O–H structure has attracted considerable interest. From insights developed by Bordwell [ 73 , 74 ] and applied more recently to metal-oxo species by Mayer [ 75 , 76 ], the O–H bond strength ( D (O–H)) of compound II can be determined from the one-electron reduction potential of compound I and the p K a of compound II using a Hess cycle (eq 1, Fig. 7 ).…”

Section: Mechanisms Of C–h Activation By Cytochrome P450s and Other Imentioning

confidence: 99%

Beyond ferryl-mediated hydroxylation: 40 years of the rebound mechanism and C–H activation

2016

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Since our initial report in 1976, the oxygen rebound mechanism has become the consensus mechanistic feature for an expanding variety of enzymatic C–H functionalization reactions and small molecule biomimetic catalysts. For both the biotransformations and models, an initial hydrogen atom abstraction from the substrate (R–H) by high-valent iron-oxo species (Fen=O) generates a substrate radical and a reduced iron hydroxide, [Fen−1–OH ·R]. This caged radical pair then evolves on a complicated energy landscape through a number of reaction pathways, such as oxygen rebound to form R–OH, rebound to a non-oxygen atom affording R–X, electron transfer of the incipient radical to yield a carbocation, R+, desaturation to form olefins, and radical cage escape. These various flavors of the rebound process, often in competition with each other, give rise to the wide range of C–H functionalization reactions performed by iron-containing oxygenases. In this review, we first recount the history of radical rebound mechanisms, their general features, and key intermediates involved. We will discuss in detail the factors that affect the behavior of the initial caged radical pair and the lifetimes of the incipient substrate radicals. Several representative examples of enzymatic C–H transformations are selected to illustrate how the behaviors of the radical pair [Fen−1–OH ·R] determine the eventual reaction outcome. Finally, we discuss the powerful potential of “radical rebound” processes as a general paradigm for developing novel C–H functionalization reactions with synthetic, biomimetic catalysts. We envision that new chemistry will continue to arise by bridging enzymatic “radical rebound” with synthetic organic chemistry.

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Electron photodetachment from mercaptyl anions (RS-). Electron affinities of mercaptyl radicals and the sulfur-hydrogen bond strength in mercaptans

Cited by 82 publications

References 7 publications

Reactions of OH and OD radicals with simple thiols and sulfides studied by infrared chemiluminescence of isotopic water products: Reaction OH + CH₃SH revisited

Reactions of OH and OD radicals with simple thiols and sulfides studied by infrared chemiluminescence of isotopic water products: Reaction OH + CH₃SH revisited

Rate constants and vibrational distributions for water‐forming reactions of OH and OD radicals with thioacetic acid, 1,2‐ethanedithiol and tert‐butanethiol

Beyond ferryl-mediated hydroxylation: 40 years of the rebound mechanism and C–H activation

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Electron photodetachment from mercaptyl anions (RS-). Electron affinities of mercaptyl radicals and the sulfur-hydrogen bond strength in mercaptans

Cited by 82 publications

References 7 publications

Reactions of OH and OD radicals with simple thiols and sulfides studied by infrared chemiluminescence of isotopic water products: Reaction OH + CH3SH revisited

Reactions of OH and OD radicals with simple thiols and sulfides studied by infrared chemiluminescence of isotopic water products: Reaction OH + CH3SH revisited

Rate constants and vibrational distributions for water‐forming reactions of OH and OD radicals with thioacetic acid, 1,2‐ethanedithiol and tert‐butanethiol

Beyond ferryl-mediated hydroxylation: 40 years of the rebound mechanism and C–H activation

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Reactions of OH and OD radicals with simple thiols and sulfides studied by infrared chemiluminescence of isotopic water products: Reaction OH + CH₃SH revisited

Reactions of OH and OD radicals with simple thiols and sulfides studied by infrared chemiluminescence of isotopic water products: Reaction OH + CH₃SH revisited