Oxysulfur Compounds Derived from Dimethyl Disulfide:  An ab Initio Study

Abstract

The optimized geometries of oxysulfur compounds derived from dimethyl disulfide were calculated at the MP2/6-31G* level, and the relative energies of isomers in the CH 3 S 2 OCH 3 , CH 3 S 2 O 2 CH 3 , CH 3 S 2 O 3 CH 3 , and CH 3 S 2 O 4 CH 3 series were compared. All these derivatives are characterized by long S-S bonds or long sulfenyl or sulfinyl S-O bonds for sulfur-oxygen-bridged isomers. According to the geometrical parameters calculated for vic-disulfoxide 4RR in the CH 3 S 2 O 2 CH 3 series, this compound is better described as two interacting sulfinyl radicals, and the obtained results substantiate the experimental scheme proposed by Clennan 28 for the intramolecular singlet oxygen addition on disulfides. The UV spectra of all these isomers were evaluated at a standard ab initio level: despite underestimated wavelengths, their evolution (wavelengths and molar extinction coefficients) is consistent with experiment and indicates a strong influence of the σ S-S ,n S f σ* S-S transition for sulfur-sulfur-bridged isomers and of n S ,n O f σ* S-O transitions for sulfur-oxygenbridged isomers. As a result, these compounds will be cleaved photochemically by S-S or alternatively by sulfenyl or sulfinyl S-O bond cleavage, leading to oxysulfur radicals. The numerous experimental data on oxysulfur molecules and radicals are discussed in light of the predicted stability and photochemical reactivity of both classes of molecules. The validity of this standard method of evaluation of UV spectra was further assessed by a more accurate calculation on a known stable model compound, methyl methanethiosulfinate (2), by use of an extensive configuration interaction treatment (MRSDCI formalism).

Transient infrared spectra of CH3SOO and CH3SO observed with a step-scan Fourier-transform spectrometer

“…CH 3 S͑O͒OSCH 3 might be produced from reactions of CH 3 SO+ CH 3 SO or CH 3 SOO+ CH 3 S. Lacombe et al 64 also demonstrated that the self-reaction of CH 3 SO might produce CH 3 S͑O͒OSCH 3 and CH 3 S͑O͒S͑O͒CH 3 , CH 3 SO + CH 3 SO → CH 3 S͑O͒OSCH 3 ͑8͒ ⌬H = − 68 kJ mol −1 , The two additional intense bands of CH 3 S͑O͒OSCH 3 are predicted at 759 and 623 cm −1 , beyond our detection limit.…”

Direct Observation of Photochromic Dynamics in the Crystalline State of an Organorhodium Dithionite Complex

“…Complex 2 contains new oxysulfide species O 2 SOSO with an oxo bridge between the two S atoms: S1 has two terminal O atoms, while S2 has only one terminal O atom and is asymmetric (Figure 1, right). The O 2 SOSO type of oxysulfur and oxysulfide compounds is unknown to date but has been theoretically calculated [13] . The bridging S1ÀO5 and S2ÀO5 bonds in 2 differ significantly in length (S1ÀO5 1.709(5), S2ÀO5 1.636(6) ), and the latter has double-bond character.…”

Direct Observation of Photochromic Dynamics in the Crystalline State of an Organorhodium Dithionite Complex

“…The m-O 2 SSO 2 ligand in 1 has a weak S À S bond of 2.330(2) . The O 2 SOSO type of oxysulfur and oxysulfide compounds is unknown to date but has been theoretically calculated [13] . Complex 2 contains new oxysulfide species O 2 SOSO with an oxo bridge between the two S atoms: S1 has two terminal O atoms, while S2 has only one terminal O atom and is asymmetric (Figure 1, right).…”