Ionic dissociation of hydrogen bromide in water clusters: a computational study

Conley, Clinton T.; Fang, Tao

doi:10.1016/s0009-2614(99)00018-4

Cited by 64 publications

(59 citation statements)

References 12 publications

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“…2 However, results of a molecular mechanics calculation suggested that HCl should ionize spontaneously on an ice surface. 3 Other computational results are in general agreement that a cluster of four water molecules will dissociate a single adsorbed HX 4,5 (and other references in ref 6), but the system must first assume a favorable coordination geometry, requiring mobility that may be missing at surfaces of clusters, ice particles, and ice films at low temperatures. Recently, detailed reports suggesting the retention of a high fraction of molecular HCl for dilute coverage of ice films (refs 7 and 8, reactive ion scattering) and ice nanocrystals (ref 6, FTIR spectra) up to 90 K seemed to establish rough limits to the kinetic stabilization of molecular HX at an ice surface.…”

Section: Introductionsupporting

confidence: 57%

Comparative FTIR Spectroscopy of HX Adsorbed on Solid Water: Ragout-Jet Water Clusters vs Ice Nanocrystal Arrays

et al. 2005

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In addition to revealing the stretch-mode bands of the smallest mixed clusters of HCl and HBr (HX) with water, the ragout-jet FTIR spectra of dense mixed water-acid supersonic jets include bands that result from the interaction of HX with larger water clusters. It is argued here that low jet temperatures prevent the water-cluster-bound HX molecules from becoming sufficiently solvated to induce ionic dissociation. The molecular nature of the HX can be deduced directly from the observed influence of changing from HCl to HBr and from replacing H2O with D2O. Furthermore, the band positions of HX are roughly coincidental with bands assigned to molecular HCl and HBr adsorbed on ice nanocrystal surfaces at temperatures below 100 K. It is also interesting that the HX band positions and widths approximate those of HX bound to the surface of amorphous ice films at <60 K. Though computational results suggest the adsorbed HX molecules observed in the jet expansions are weakly distorted by single coordination with surface dangling-oxygen atoms, on-the-fly trajectories indicate that the cluster skeletons undergo large-amplitude low-frequency vibrations. Local HX solvation, the extent of proton sharing, and the HX vibrational spectra undergo serious modulation on a picosecond time scale.

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Section: Introductionsupporting

confidence: 57%

Comparative FTIR Spectroscopy of HX Adsorbed on Solid Water: Ragout-Jet Water Clusters vs Ice Nanocrystal Arrays

et al. 2005

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“…126 124,125 and suggest that solvation of the I Ϫ -like moiety occurs in the (CH 2 I-I)H 2 O and ͓CH 2 I(OH)͔H 2 O RCs. Figure 8 shows a comparison of the stabilization energies of the RCs and the reaction enthalpies for the CH 2 I(OH)ϩnH 2 O ͑where nϭ0,1,2,3,4) reactions plotted along with the relative energy for the barrier to reaction from the RCs to their respective TS as a function of H 2 O molecules.…”

Section: And Solvation Of the Hi Leaving Groupmentioning

confidence: 99%

Efficient dehalogenation of polyhalomethanes and production of strong acids in aqueous environments: Water-catalyzed O–H-insertion and HI-elimination reactions of isodiiodomethane (CH2I–I) with water

Kwok

Zhao

Guan

et al. 2004

The Journal of Chemical Physics

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A combined experimental and theoretical study of the ultraviolet photolysis of CH2I2 in water is reported. Ultraviolet photolysis of low concentrations of CH2I2 in water was experimentally observed to lead to almost complete conversion into CH2(OH)2 and 2HI products. Picosecond time-resolved resonance Raman spectroscopy experiments in mixed water/acetonitrile solvents (25%-75% water) showed that appreciable amounts of isodiiodomethane (CH2I-I) were formed within several picoseconds and the decay of the CH2I-I species became substantially shorter with increasing water concentration, suggesting that CH2I-I may be reacting with water. Ab initio calculations demonstrate the CH2I-I species is able to react readily with water via a water-catalyzed O--H-insertion and HI-elimination reaction followed by its CH2I(OH) product undergoing a further water-catalyzed HI-elimination reaction to make a H2C=O product. These HI-elimination reactions produce the two HI leaving groups observed experimentally and the H2C=O product further reacts with water to produce the other final CH2(OH)2 product observed in the photochemistry experiments. These results suggest that CH2I-I is the species that reacts with water to produce the CH2(OH)2 and 2HI products seen in the photochemistry experiments. The present study demonstrates that ultraviolet photolysis of CH2I2 at low concentration leads to efficient dehalogenation and release of multiple strong acid (HI) leaving groups. Some possible ramifications for the decomposition of polyhalomethanes and halomethanols in aqueous environments as well as the photochemistry of polyhalomethanes in the natural environment are briefly discussed.

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“…This structure has not been identified as the energy minimum of the n ϭ 4 complex, so that a goal of future work will be to refine calculations to establish whether its preferential formation is driven by thermochemistry or kinetics. This compact, tricyclic isomer is strongly reminiscent of the charge-separated form of the HBr⅐(H 2 O) 4 cluster (41)(42)(43)(44), where calculations suggest that three bridging water molecules separate the Br Ϫ and H 3 O ϩ ion pair in a C 3 symmetry species (45).…”

mentioning

confidence: 99%

Spectroscopic Determination of the OH ⁻ Solvation Shell in the OH ⁻ ·(H ₂ O) _n Clusters

Robertson

Diken

Price

et al. 2003

Science

365

209

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There has been long-standing uncertainty about the number of water molecules in the primary coordination environment of the OH- and F- ions in aqueous chemistry. We report the vibrational spectra of the OH-.(H2O)n and F-.(H2O)n clusters and interpret the pattern of OH stretching fundamentals with ab initio calculations. The spectra of the cold complexes are obtained by first attaching weakly bound argon atoms to the clusters and then monitoring the photoinduced evaporation of these atoms when an infrared laser is tuned to a vibrational resonance. The small clusters (n

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Ionic dissociation of hydrogen bromide in water clusters: a computational study

Cited by 64 publications

References 12 publications

Comparative FTIR Spectroscopy of HX Adsorbed on Solid Water: Ragout-Jet Water Clusters vs Ice Nanocrystal Arrays

Comparative FTIR Spectroscopy of HX Adsorbed on Solid Water: Ragout-Jet Water Clusters vs Ice Nanocrystal Arrays

Efficient dehalogenation of polyhalomethanes and production of strong acids in aqueous environments: Water-catalyzed O–H-insertion and HI-elimination reactions of isodiiodomethane (CH2I–I) with water

Spectroscopic Determination of the OH ⁻ Solvation Shell in the OH ⁻ ·(H ₂ O) _n Clusters

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Ionic dissociation of hydrogen bromide in water clusters: a computational study

Cited by 64 publications

References 12 publications

Comparative FTIR Spectroscopy of HX Adsorbed on Solid Water: Ragout-Jet Water Clusters vs Ice Nanocrystal Arrays

Comparative FTIR Spectroscopy of HX Adsorbed on Solid Water: Ragout-Jet Water Clusters vs Ice Nanocrystal Arrays

Efficient dehalogenation of polyhalomethanes and production of strong acids in aqueous environments: Water-catalyzed O–H-insertion and HI-elimination reactions of isodiiodomethane (CH2I–I) with water

Spectroscopic Determination of the OH − Solvation Shell in the OH − ·(H 2 O) n Clusters

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Spectroscopic Determination of the OH ⁻ Solvation Shell in the OH ⁻ ·(H ₂ O) _n Clusters