ESR studies of the thietane and thiirane radical cations in freon matrices. Evidence for ethylene molecule extrusion from the sigma* thiirane dimer radical cation (C/sub 2/H/sub 4/S-SC/sub 2/H/sub 4//sup. +/

Journal Article · Wed Oct 28 00:00:00 EST 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00256a036· OSTI ID:5418961

Qin, X Z; Meng, Q; Williams, F

ESR spectroscopy has been used to study the structures and reactions of the radical cations produced from the three- and four-membered sulfur-containing ring compounds, thiirane and thietane, the radical cations being generated by ..gamma.. irradiation of dilute solutions of the parent compounds in Freon matrices at 77 K. With use of CFCl/sub 3/ as the matrix, the monomer radical cations have been identified and characterized as having /sup 2/B/sub 1/ ring-closed structures with the unpaired electron localized on the sulfur atom. The hyperfine coupling to the four equivalent ..beta..-hydrogens in the thietane cation (31.1 G) is normal, but the corresponding value for the thiirane cation (16.1 G) is lower by almost a factor of 2, suggesting that hyperconjugation to methylene groups is much reduced in three-membered rings. In the more mobile CFCl/sub 2/CF/sub 2/Cl and CF/sub 3/CCl/sub 3/ matrices, dimer radical cations of thiirane and thietane are produced by the combination of a monomer radical cation with a neutral molecule at low temperatures (< 100 K). ESR studies show that these dimer species are centrosymmetric, the binding between the molecules resulting from the formation of a 3-electron sigma/sup 2/sigma*/sup 1/ S-S bond. Both of the dimer cations are unstable above 105 K in the CFCl/sub 2/CF/sub 2/Cl matrix, the thietane dimer radical cation decomposing to give the 2-thietanyl radical as a result of hydrogen atom or proton transfer, whereas the thiirane dimer radical cation undergoes a novel reaction involving the extrusion of an ethylene molecule.

• Research Organization: Univ. of Tennessee, Knoxville
• OSTI ID: 5418961
• Journal Information: J. Am. Chem. Soc.; (United States), Vol. 109:22
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ORGANIC SULFUR COMPOUNDS
CHEMICAL REACTIONS
MOLECULAR STRUCTURE
CATIONS
DIMERS
ELECTRON SPIN RESONANCE
EXPERIMENTAL DATA
FREONS
MATRIX ISOLATION
RADICALS
CHARGED PARTICLES
DATA
HALOGENATED ALIPHATIC HYDROCARBONS
INFORMATION
IONS
MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
RESONANCE
400201* - Chemical &amp; Physicochemical Properties