Synthesis and electron spin resonance spectroscopy of organo-sulfur radical cations

Date
1986
Authors
Law, Wing
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Altmetrics
Authors
Research Projects
Organizational Units
Chemistry
Organizational Unit
Journal Issue
Series
Department
Chemistry
Abstract

A series of new radical cations in 1,4-dithiin, 1,4-benzodithiin, 2,3-dihydro-1,4-dithiin, 1,4-dithiepin, 1,2-dithietane, 1,2-dithiolane, 1,2-dithiane series were prepared. The SOMO of 1,4-dithiin, 1,4-benzodithiin, 2,3-dihydro-1,4-dithiin radical cations were found to be symmetrical while the SOMO of cyclic 1,2-disulfide radical cations were found to be antisymmetrical. 2,3-Dihydro-1,4-dithiin, 1,4-dithiepin radical cations were found to have conformational preference at low temperature and the activation parameters for the ring inversion processes were obtained. For 1,2-bis(isopropylthio)cyclohexene radical cation, the unusually low value of (DELTA)H('(NOT=)) for the cyclohexene ring inversion was explained by secondary interactions between the isopropyl groups and the (alpha) methylene groups. Sulfur-centered radical cations were found to be capable of showing sizable long range couplings in the radical cations of 2,5-dithiabicyclo 4.2.1 non-3-ene, 2,3-dithiabicyclo 2.2.1 heptane, 2,3-dithiabicyclo 2.2.2 octane. It is established from all the ESR results that the hfs of a hydrogen (beta) to a sulfur atom with spin density arises predominantly from angle-dependent hyperconjugation. For disulfide radical cations (not including 1,2-dithietane radical cations), a value of 35 G was calculated for the constant B which is a measure of the magnitude of this interaction. For 1,2-dithietane radical cations, a (sigma)-delocalized electronic structure for the 3-electron bond is proposed to explain the unusual conformational preference and the unusually low values of a('H);Sulfur-centered radical cations were generated by oxidative rearrangement. Thus, 2,2-dialkyl-1,3-dithiolanes rearranged to form 2,3-dihydro-1,4-dithiin radical cations when treated with either H(,2)SO(,4) or Al(,2)Cl(,6)/CH(,2)Cl(,2). Similarly, 2,3-dialkyl-1,3-benzodithioles rearranged to form the 1,4-benzodithiin radical cations. Diaryl disulfides underwent oxidative rearrangement to form benzodithiete and thianthrene radical cations. Methylbenzyl disulfides underwent oxidative rearrangement to form polymethylbenzodithiete and 2,6-dimethylanthrancene radical cations.

Comments
Description
Keywords
Citation
Source