Gas‐Phase Detection of HSOH: Synthesis by Flash Vacuum Pyrolysis of Di‐tert‐butyl Sulfoxide and Rotational‐Torsional Spectrum

Abstract

Gas-phase oxadisulfane (HSOH), the missing link between the well-known molecules hydrogen peroxide (HOOH) and disulfane (HSSH), was synthesized by flash vacuum pyrolysis of di-tert-butyl sulfoxide. Using mass spectrometry, the pyrolysis conditions have been optimized towards formation of HSOH. Microwave spectroscopic investigation of the pyrolysis products allowed-assisted by high-level quantum-chemical calculations--the first measurement of the rotational-torsional spectrum of HSOH. In total, we have measured approximately 600 lines of the rotational-torsional spectrum in the frequency range from 64 GHz to 1.9 THz and assigned some 470 of these to the rotational-torsional spectrum of HSOH in its ground torsional state. Some 120 out of the 600 lines arise from the isotopomer H(34)SOH. The HSOH molecule displays strong c-type and somewhat weaker b-type transitions, indicating a nonplanar skew chain structure, similar to the analogous molecules HOOH and HSSH. The rotational constants (MHz) of the main isotopomer (A=202 069, B=15 282, C=14 840), determined by applying a least-squares analysis to the presently available data set, are in excellent agreement with those predicted by quantum-chemical calculations (A=202 136, B=15 279, C=14 840). Our theoretical treatment also derived the following barrier heights against internal rotation in HSOH (when in the cis and trans configurations) to be V(cis) approximately equal to 2216 cm(-1) and V(trans) approximately equal to 1579 cm(-1). The internal rotational motion results in detectable torsional splittings that are dependent on the angular momentum quantum numbers J and K(a).

High-resolution infrared measurements on HSOH: Analysis of the OH fundamental vibrational mode

“…First experimental evidence of a skew chain structure, very similar to the cases of HOOH and HSSH, came from high-resolution millimeter-wave spectroscopy on HSOH and H 34 SOH [1]. The authors used flash vacuum pyrolysis of di-tert-butyl sulfoxide to produce HSOH, a novel pathway which had been introduced by Hahn et al and Behnke in 2001 [1,2].…”

FeS-Induced Radical Formation and Its Effect on Plasmid DNA

“…into HS • radicals is a new reaction, although not unexpected as H 2 S 2 is analogous in many ways to H 2 O 2 (Winnewisser et al 2003). It is possible that other sulfide free radicals, such as H 2 S 2 -that is energetically favored (Mills et al 1987), are possible reactants.…”

“…The bisulfide free radical is analogous to the hydroxyl radical OH • . And, of course, the fully protonated disulfide, H 2 S 2 , is the sulfur analog of H 2 O 2 (Winnewisser et al 2003). The formation of sulfide free radicals in aqueous solutions by a mechanism analogous to Fenton's reaction for oxygen free radicals is further suggested by comparative frontier molecular orbital considerations.…”

Mode-selective stereomutation tunneling and parity violation in HOClH+ and H2Te2 isotopomers

“…There have also been parity conserving quantum chemical studies of H 2 Te 2 [35] and HOClH + [36][37][38][39]. This ion is isoelectronic to HSOH which has been generated in mass spectroscopic experiments [40] and more recently in bulk [41]. This molecule also falls in the general series of axially chiral molecules HXYH, for which we have already presented extensive calculations of parity violation and tunneling in our previous work [21][22][23][24][25][26][27]32,33,42,43].…”