Does H<sub>4</sub>SO<sub>5</sub> exist?

Murillo, Fernando; Vargas-Caamal, Alba; Pan, Sudip; Cabellos, José Luis; Mora-Fonz, Miguel J.; Muñoz-Castro, Álvaro; Restrepo, Albeiro; Merino, Gabriel

doi:10.1039/c7cp01328k

Cited by 8 publications

(6 citation statements)

References 30 publications

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“…The reaction H2O + SO4 2-(+2H + ) ↔ HSO5 3-+ H + (+2H + ) proceeds to the right with an equilibrium constant K(25°) = 9.1×10 36 , thus G o = 211 kJ/mol (50 kcal/mol) [4]. However, HSO5 3is not stable in nonacidic solution [4,5], and this was stated very clearly (in Ref. 5, on p. 11683): "…HSO5 3is stable only under strongly acidic conditions, and it collapses to the tetrahedral SO4 2structure upon neutralization."…”

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confidence: 99%

The electric conductance of dilute sulfuric acid in water: a new theoretical interpretation

Fraenkel

2021

Molecular Physics

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Modeling of sulfuric acid in solution is of much interest and importance in science and technology. Murillo et al. have recently conducted a quantum chemical (QC) study by which they computed the thermodynamic and kinetic stability of para-sulfuric acid, H4SO5 [1]. They concluded that H4SO5 is "not a viable system in solution." The correctness of their work is obviously subject to the physicochemical validity of their assumptions on the structural details of the aqueous acid and its ions (effective atomic charge, atom-atom bonding character, acid-water coordination, solvation effects, etc.), as set forth in their investigation. Thus, what is found "not viable" are the specific isolated structures as described and analysed by those authors.There are at least two major problems with the analysis of Murillo et al., related specifically to their way of dealing with H4SO5. First, the authors, through their calculation technique, regarded the acid as a stereochemically rigid structure with distinct single and double S-O bonds (see Figures in Ref. 1). In doing so, not only did they disregard the likelihood that parasulfuric acid, like other five-coordinate complex molecular arrangements [2], is a non-rigid, fluxional structure that may be visualised as a time-average of different structures of trigonal bipyramid (tbp) and square pyramid (spy) configurations [2]; but, in addition, they also ignored the electron resonance between single and double sulfur-oxygen bonds due to fast electron delocalization [2,3]. (For more discussion on fluxional behavior and electron resonance in sulfur oxide structures, see SM-2.) The above two bonding effects, namely stereochemical non-rigidity and electron resonance, may lend H4SO5 a considerable extra stability over its rigid, nonresonance structures. The latter may exist and be stable at very low temperature where the time scale of the transitions from one to another conformation/configuration may be longer than the time scale of the chemical or spectroscopic method applied to elucidate and/or detect the H4SO5 structure (e.g., Raman, NMR).

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confidence: 99%

The electric conductance of dilute sulfuric acid in water: a new theoretical interpretation

Fraenkel

2021

Molecular Physics

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“…These constraints have been sufficient to successfully explore the PESs of several molecular clusters. [22,28,[30][31][32] Once it was determined how the initial structures would be constructed, a hierarchical screening was established so that the initial structures were optimized at the PBE0/D95V level and then refined at the PBE0-D3/def2-TZVP level. [33][34][35] Each structure was characterized as a true minimum by harmonic vibrational frequency analysis.…”

Section: Computational Detailsmentioning

confidence: 99%

Acid Dissociation in (HX)_n(H₂O)_nClusters (X=F, Cl, Br, I;n=2, 3)**

et al. 2022

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In this work, we analyze the interactions between two or three hydrogen halide molecules and the same number of water moieties through a systematic exploration of their potential energy surfaces. Our results indicate that the most stable HF and HCl aggregates do not experience dissociation of any of the acid fragments, even with three water molecules. In contrast, in the HBr and HI clusters, one of the acid fragments does dissociate. While the global minimum of (HBr) 3 (H 2 O) 3 is a hydrogen-bridged bihalide anion (BrHBr À ), which is persistent at temperatures up to 203 K, the lowest energy structure of (HI) 3 (H 2 O) 3 has a separated ion pair, but the motif with a bihalide anion (IHI À ) is only 0.2 kcal mol À 1 above the global minimum. Among the more stable structures is a broad spectrum of contacts, including water⋯water, HX⋯water, and HX⋯HX hydrogen bonds, halogen bonds, ionic and long-range X⋯H contacts.

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“…This conclusion was supported by the absence of one O═S═O vibrational band at 1,150 cm −1 , which is a characteristic of H 2 SO 4 . Murillo et al [44] explored the possible existence of H 4 SO 5 and found that the computed free energy barrier for the transformation of H 4 SO 5 into the H 2 SO 4 ─H 2 O complex is only 3.8 kcal mol −1 . These authors further proposed that in the gas phase, dehydration of H 4 SO 5 is an autocatalytic reaction as the water molecule produced by the decomposition of one H 4 SO 5 molecule induces further dissociation.…”

Section: Sulfuric Acidmentioning

confidence: 99%

Standoff Raman spectroscopy for future Europa Lander missions

Sharma

Porter

Misra

et al. 2020

J Raman Spectroscopy

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Near Infrared Mapping Spectrograph data from the Galileo spacecraft and cryogenic laboratory reflectance measurements on hydrated compounds identified the presence of mixtures of hydrous magnesium sulfate, sulfuric acid, and hydrogen peroxide on the surface of Europa. Standoff Raman spectroscopy is ideally suited for exploring terrestrial Europa analog sites and Europa because of its ability to unambiguously identify minerals, organic compounds, and biomarkers inside ice. In the present work, we evaluated the performance of a standoff Raman system at various distances by measuring Raman spectra of hydrogen peroxide, sulfuric acid, and hydrous sulfate minerals, which are predicted to be present on Europa's surface. To simulate Europa's surface environment, Raman spectra of MgSO4·7H2O, FeSO4·7H2O, gypsum (CaSO4·2H2O), dry ice (CO2‐ice), and polycyclic aromatic hydrocarbons (PAHs) naphthalene and anthracene inside crushed H2O‐ice, shaved H2O‐ice, and a clear H2O‐ice block have also been measured. The PAHs were selected in this study because of their presence in the interstellar medium, comets, and meteorites. The results show that it will be possible to map out the non‐ice components on the surface and subsurface of Europa analog sites and Europa up to a distance of 120 m from a static lander and to a depth of ~10 cm inside ice. We have evaluated the performance of a standoff Raman system at various distances by measuring Raman spectra of hydrogen peroxide, sulfuric acid, and hydrous sulfate minerals, which are predicted to be present on Europas surface. To simulate Europas surface environment, Raman spectra of MgSO4·7H2O, FeSO4·7H2O, gypsum (CaSO4·2H2O), dry ice (CO2‐ice), and polycyclic aromatic hydrocarbons (PAHs) naphthalene and anthracene inside crushed H2O‐ice, shaved H2O‐ice, and H2O‐ice block have been measured.

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Does H₄SO₅ exist?

Cited by 8 publications

References 30 publications

The electric conductance of dilute sulfuric acid in water: a new theoretical interpretation

The electric conductance of dilute sulfuric acid in water: a new theoretical interpretation

Acid Dissociation in (HX)_n(H₂O)_nClusters (X=F, Cl, Br, I;n=2, 3)**

Standoff Raman spectroscopy for future Europa Lander missions

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Does H4SO5 exist?

Cited by 8 publications

References 30 publications

The electric conductance of dilute sulfuric acid in water: a new theoretical interpretation

The electric conductance of dilute sulfuric acid in water: a new theoretical interpretation

Acid Dissociation in (HX)n(H2O)nClusters (X=F, Cl, Br, I;n=2, 3)**

Standoff Raman spectroscopy for future Europa Lander missions

Contact Info

Product

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About

Does H₄SO₅ exist?

Acid Dissociation in (HX)_n(H₂O)_nClusters (X=F, Cl, Br, I;n=2, 3)**