Spectroscopic Detection and Structure of Hydroxidooxidosulfur (HOSO) Radical, An Important Intermediate in the Chemistry of Sulfur-Bearing Compounds

Abstract

The rotational spectrum of hydroxidooxidosulfur, HOSO, an intermediate of particular interest in the combustion of sulfur-rich fuels, has been determined to high accuracy from gas-phase measurements. Detection of specific isotopic species using isotopically enriched gases suggests that HOSO is formed in our discharge nozzle via the reaction H + SO 2 (+M) → HOSO (+M). A precise experimental r 0 geometry has also been derived from the isotopic analysis; HOSO has a cis configuration, but the subtle structural question of its planarity remains unresolved. From the derived spectroscopic constants, in situ and remote sensing for this fundamental radical can now be undertaken in a variety of environments, including in combustion reactors, the troposphere of Earth, and Io, the innermost Galilean moon of Jupiter.

Coupled-Cluster Study of the Lower Energy Region of the Ground Electronic State of the HSO2 Potential Energy Surface

“…36 According to their analysis, this result could indicate (a) a planar geometry for the sp-HOSO isomer; (b) a vibrationally averaged planar structure, or (c) a dihedral angle for the sp-HOSO minimum smaller than those reported by theoretical calculations. However, the same authors also report a small negative inertial defect as a possible experimental evidence for a slightly nonplanar structure.…”

Fundamental Vibrational Frequencies and Spectroscopic Constants of cis- and trans-HOCS, HSCO, and Isotopologues via Quartic Force Fields

“…Similarly, HOCS and HSCO are also viable candidates for Special Issue: William C. Swope Festschrift detection in space, and the related HOSO radical is believed to be present in combustion flames. 7,24 The HOCS and HSCO potential energy surfaces are slightly more complicated than their corresponding cations. Like HOCO + , HOCS + and HSCO + both only exist as trans conformers with the heavy-atom bond angle approaching 180°.…”

Hydrogen bonding in the hydroxysulfinyl radical-formic acid-water system: A theoretical study

“…In parentheses are the CCSD/aug‐cc‐pVDZ parameters, and in bold are experimental parameters from Refs. . Bond lengths are in Å.…”

“…The experimental parameters available for all monomeric species and for the formic acid dimer are written in bold in Figure and Supporting Information Figure SI‐1, respectively. The very recent work of McCarthy et al presents a report on the experimental geometry of the HOSO radical, studied by Fourier transform (FT) microwave spectroscopy. The calculated values at the B3LYP level and experimental structural parameters are in fairly well agreement.…”

“…The first experimental evidence for the existence of the HOSO radical in the gas phase was provided through its identification by the neutralization‐reionization mass spectrometry method . Several years later, it was also detected in many other experiments using matrix isolation methods and FT microwave spectroscopy . Theoretical investigations have been conducted with the goal of characterizing the structure, harmonic vibrational frequencies, and thermochemistry, whereas little attention has been paid to the reactions of this radical and its ability to form complexes .…”