Filling of solvent shells about ions. 1. Thermochemical criteria and the effects of isomeric clusters

Meot‐Ner, Michael; Speller, C. V.

doi:10.1021/j100283a006

Cited by 208 publications

(127 citation statements)

References 6 publications

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“…The trends ( Table 3) strongly suggest that in the gas-phase the n=4 cluster in fact must involve an outer-sphere arrangement of the fourth water. This shell-closure at n=3 was inferred by Moet-Ner and Speller [27] based on their thermochemical analysis of the stepwise attachment of water to HO − . These authors also noted possible artifacts in a much earlier work [28] that did not show the shell effect.…”

Section: Discussionmentioning

confidence: 66%

The hydration state of HO−(aq)

Asthagiri

Pratt

Kress

et al. 2003

Chemical Physics Letters

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The HO − (aq) ion participates in myriad aqueous phase chemical processes of biological and chemical interest. A molecularly valid description of its hydration state, currently poorly understood, is a natural prerequisite to modeling chemical transformations involving HO − (aq). Here it is shown that the statistical mechanical quasichemical theory of solutions predicts that− is the dominant inner shell coordination structure for HO − (aq) under standard conditions. Experimental observations and other theoretical calculations are adduced to support this conclusion. Hydration free energies of neutral combinations of simple cations with HO − (aq) are evaluated and agree well with experimental values.

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Section: Discussionmentioning

confidence: 66%

The hydration state of HO−(aq)

Asthagiri

Pratt

Kress

et al. 2003

Chemical Physics Letters

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“…Three distinct lines of investigation, theory (22), experiments (18,23), and the present simulations (and also ref. Ϫ is a prominent subgrouping within larger inner shell structures.…”

Section: Resultsmentioning

confidence: 77%

Hydration and mobility of HO^-(aq)

Asthagiri

Pratt

Kress

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

150

148

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The hydroxide anion plays an essential role in many chemical and biochemical reactions. But a molecular-scale description of its hydration state, and hence also its transport, in water is currently controversial. A preeminent challenge in liquid-state physics is the understanding of aqueous phase chemical transformations on a molecular scale. Water undergoes limited autoprotolysis, which is enhanced in the presence of highly charged metal ions such as Be 2ϩ (1, 2). Understanding the hydration and transport of the autoprotolysis products, H ϩ and HO Ϫ , presents unique and interesting challenges for molecular-scale theories of solutions and for simulations. In this paper we focus on HO Ϫ (aq).Because H ϩ and HO Ϫ constitute the underlying aqueous matrix, it is not unreasonable to expect that their transport in water is different from the transport of other aqueous ions. This anomalous diffusion of the H ϩ (aq) and HO Ϫ (aq) has received extensive scrutiny over the years (for example, refs. 3-5), but recently ab initio molecular dynamics (AIMD) capabilities have evolved to provide new information on the solution condition and transport of these species. Over a similar period, the statistical mechanical theory of liquids (especially water) has also become more sophisticated (for example, ref. 6). These two approaches can be complementary, but in typical practice they remain imperfectly connected (but see refs. 2 and 7-11).In an initial AIMD study (12) Ϫ species was 2-3 ps, but statistical characterization was sketchy.Discussions of a transport mechanism for HO Ϫ (aq) typically focus on Agmon's (14, 15) extraction of an activation energy for hydroxide transport from the temperature dependence of the experimental mobilities. Near room temperature that empirical parameter is about 3 kcal͞mol, but it increases by roughly a factor of 2 for slightly lower temperatures. As a mechanical barrier this value, about 5-6 k B T, may be low enough to require some subtlety of interpretation (16); the observed temperature sensitivity of the activation energy, and particularly its increase with decreasing temperature, supports that possibility. We note that a standard inclusion of a tunneling correction would be expected to lead to a decrease of activation energy with decreasing temperature.Ref. 13 framed the consideration of HO Ϫ transport in terms of classical transition state theory and extracted an activation energy from the gas-phase study of Novoa et al. (17). Ref. 13 also considered the importance of tunneling in lowering the barrier for proton transfer by performing path integral calculations. Their combined value of 3

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“…[55] Eigen has postulated, furthermore, that a negative cluster ion HO − (H 2 O) 3 is the first hydrated shell with a C 3 symmetry, corresponding to the H 3 O + (H 2 O) 3 positive ion. [54] The stability of HO − (H 2 O) n has been estimated by several methods such as the use of the van't Hoff plot for HO − (H 2 O) n (n = 0-7), [17,56] high-resolution vibrational spectroscopy of HO − (H 2 O) n (n = 1-5) [57] and ab initio calculations of H 0 and G 0 for HO − (H 2 O) n (n = 1-4) [18] and similar calculations for the structure of HO − (H 2 O) 3 . [18,57,58] The high intensity discontinuity at the HO − (H 2 O) 3 observed in our experimental system ( Fig.…”

Section: Formation Of Ion-induced Water Clusters and First Hydrated Smentioning

confidence: 99%

Observations of different core water cluster ions Y⁻(H₂O)_n (Y = O₂, HO_x, NO_x, CO_x) and magic number in atmospheric pressure negative corona discharge mass spectrometry

Sekimoto

Takayama

2010

J. Mass Spectrom.

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Reliable mass spectrometry data from large water clusters Y(-)(H(2)O)(n) with various negative core ions Y(-) such as O(2)(-), HO(-), HO(2)(-), NO(2)(-), NO(3)(-), NO(3)(-)(HNO(3))(2), CO(3)(-) and HCO(4)(-) have been obtained using atmospheric pressure negative corona discharge mass spectrometry. All the core Y(-) ions observed were ionic species that play a central role in tropospheric ion chemistry. These mass spectra exhibited discontinuities in ion peak intensity at certain size clusters Y(-)(H(2)O)(m) indicating specific thermochemical stability. Thus, Y(-)(H(2)O)(m) may correspond to the magic number or first hydrated shell in the cluster series Y(-)(H(2)O)(n). The high intensity discontinuity at HO(-)(H(2)O)(3) observed was the first mass spectrometric evidence for the specific stability of HO(-)(H(2)O)(3) as the first hydrated shell which Eigen postulated in 1964. The negative ion water clusters Y(-)(H(2)O)(n) observed in the mass spectra are most likely to be formed via core ion formation in the ambient discharge area (760 torr) and the growth of water clusters by adiabatic expansion in the vacuum region of the mass spectrometers (≈1 torr). The detailed mechanism of the formation of the different core water cluster ions Y(-)(H(2)O)(n) is described.

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Filling of solvent shells about ions. 1. Thermochemical criteria and the effects of isomeric clusters

Cited by 208 publications

References 6 publications

The hydration state of HO−(aq)

The hydration state of HO−(aq)

Hydration and mobility of HO^-(aq)

Observations of different core water cluster ions Y⁻(H₂O)_n (Y = O₂, HO_x, NO_x, CO_x) and magic number in atmospheric pressure negative corona discharge mass spectrometry

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Filling of solvent shells about ions. 1. Thermochemical criteria and the effects of isomeric clusters

Cited by 208 publications

References 6 publications

The hydration state of HO−(aq)

The hydration state of HO−(aq)

Hydration and mobility of HO-(aq)

Observations of different core water cluster ions Y−(H2O)n (Y = O2, HOx, NOx, COx) and magic number in atmospheric pressure negative corona discharge mass spectrometry

Contact Info

Product

Resources

About

Hydration and mobility of HO^-(aq)

Observations of different core water cluster ions Y⁻(H₂O)_n (Y = O₂, HO_x, NO_x, CO_x) and magic number in atmospheric pressure negative corona discharge mass spectrometry