This paper provides evidence from kinetic experiments and electronic structure calculations of a significantly reduced S-H bond strength in the Mo(micro-SH)Mo function in the homogeneous catalyst model, CpMo(micro-S)(2)(micro-SH)(2)MoCp (1, Cp = eta(5)-cyclopentadienyl). The reactivity of 1 was explored by determination of a rate expression for hydrogen atom abstraction by benzyl radical from 1 (log(k(abs)/M(-)(1) s(-)(1)) = (9.07 +/- 0.38) - (3.62 +/- 0.58)/theta) for comparison with expressions for CH(3)(CH(2))(7)SH, log(k(abs)/M(-)(1) s(-)(1)) = (7.88 +/- 0.35) - (4.64 +/- 0.54)/theta, and for 2-mercaptonaphthalene, log(k(abs)/M(-)(1) s(-)(1)) = (8.21 +/- 0.17) - (4.24 +/- 0.26)/theta (theta = 2.303RT kcal/mol, 2sigma error). The rate constant for hydrogen atom abstraction at 298 K by benzyl radical from 1 is 2 orders of magnitude greater than that from 1-octanethiol, resulting from the predicted (DFT) S-H bond strength of 1 of 73 kcal/mol. The radical CpMo(micro-S)(3)(micro-SH)MoCp, 2, is revealed, from the properties of slow self-reaction, and exclusive cross-combination with reactive benzyl radical, to be a persistent free radical.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/ja049321r | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Molecular Photoelectrocatalysis for Radical Reactions.
Acc Chem Res
January 2025
State Key Laboratory of Physical Chemistry of Solid Surfaces, Key Laboratory of Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, and Discipline of Intelligent Instrument and Equipment, Xiamen University, Xiamen 361005, P. R. China.
ConspectusMolecular photoelectrocatalysis, which combines the merits of photocatalysis and organic electrosynthesis, including their green attributes and capacity to offer novel reactivity and selectivity, represents an emerging field in organic chemistry that addresses the growing demands for environmental sustainability and synthetic efficiency. This synergistic approach permits access to a wider range of redox potentials, facilitates redox transformations under gentler electrode potentials, and decreases the use of external harsh redox reagents. Despite these potential advantages, this area did not receive significant attention until 2019, when we and others reported the first examples of modern molecular photoelectrocatalysis.
View Article and Find Full Text PDFNickel(II)-hydrazineylpyridine catalyzed regioselective synthesis of α-benzyl substituted β-hydroxy ketones a Fenton free radical reaction.
Org Biomol Chem
January 2025
Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee-247667, Uttarakhand, India.
Ni(II)-hydrazineylpyridine (Ni(II)-PyH)-catalyzed regioselective synthesis of α-benzyl substituted β-hydroxy ketones from α,β-unsaturated ketones and alcohols is reported a Fenton free-radical reaction. This protocol enables facile access to desired products in good to excellent yields in 12 h using toluene solvent at room temperature to 100 °C. The structural analysis of the products was confirmed by H, C-NMR, GC-MS, and HRMS data.
View Article and Find Full Text PDFNovel Dithiocarbamic Flavanones with Antioxidant Properties-A Structure-Activity Relationship Study.
Int J Mol Sci
December 2024
Department of Chemistry, Alexandru Ioan Cuza University of Iasi, 11 Carol I Blvd., 700506 Iasi, Romania.
The antioxidant properties of some 3-dithiocarbamic flavanones were investigated. Based on a previous study, we selected three frameworks that proved to be the most active ones. By varying the nature of the substituent at the para-position of flavanone ring , a structure-activity relationship study on radical scavenging activities was performed.
View Article and Find Full Text PDFCombining synchrotron vacuum-ultraviolet photoionization mass spectrometry and gas chromatography-mass spectrometry for isomer-specific mechanistic analysis with application to the benzyl self-reaction.
Nat Commun
December 2024
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, PR China.
Elucidating the formation mechanism of polycyclic aromatic hydrocarbons (PAHs) is crucial to understand processes in the contexts of combustion, environmental science, astrochemistry, and nanomaterials synthesis. An excited electronic-state pathway has been proposed to account for the formation of 14π aromatic anthracene in the benzyl (b-CH) self-reaction. Here, to improve our understanding of anthracene formation, we investigate CH bimolecular reactions in a tubular SiC microreactor through an isomer-resolved method that combines in situ synchrotron-radiation VUV photoionization mass spectrometry and ex-situ gas chromatography-mass spectrometry.
View Article and Find Full Text PDFHeterocoupling Two Similar Benzyl Radicals by Dual Photoredox/Cobalt Catalysis.
Angew Chem Int Ed Engl
December 2024
College of Chemistry, Pingyuan Laboratory, Zhengzhou University, 100 Science Avenue, Zhengzhou, 450001, Henan, P. R. China.
Transition-metal-regulated radical cross coupling enables the selective bonding of two distinct transient radicals, whereas the catalytic method for sorting two almost identical transient radicals, especially similar benzyl radicals, is still rare. Herein, we show that leveraging dual photoredox/cobalt catalysis can selectively couple two similar benzyl radicals. Using easily accessible methylarenes and phenylacetates (benzyl N-hydroxyphthalimide (NHPI) esters) as benzyl radical sources, a range of unsymmetrical 1,2-diarylethane classes via the 1°-1°, 1°-2°, 1°-3°, 2°-2°, 2°-3° and 3°-3° couplings were obtained with broad functional group tolerance.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!