However, recent studies have identified OH(-) hydration complexes that bear little structural similarity to proton hydration complexes. The reason for this may be attributed to the century-old notion that a hydrated OH(-) can be regarded as a water molecule missing a proton, and that the transport mechanism of such a 'proton hole' can be inferred from that of an excess proton by simply reversing hydrogen bond polarities. In contrast, hydroxide ion mobility in basic solutions has received far less attention, even though bases and base catalysis play important roles in many organic and biochemical reactions and in the chemical industry. Detailed investigations have led to a clear understanding of the proton transport mechanism at the molecular level. On a qualitative level, this behaviour has long been explained by 'structural diffusion' the continuous interconversion between hydration complexes driven by fluctuations in the solvation shell of the hydrated ions. Structural and energetic parameters clearly suggest that it might be possible to prepare and characterize the HRgOH2 (+) species (except HHeOH2 (+)) using electron bombardment matrix isolation technique in a way similar to that of the preparation of (Rg2H)(+) or mixed (RgHRg('))(+) cations.Ĭompared to other ions, protons (H(+)) and hydroxide ions (OH(-)) exhibit anomalously high mobilities in aqueous solutions. The calculated values of topological properties within the framework of quantum theory of atoms-in-molecules are found to be consistent with the bond length values. Nevertheless, this 2-body dissociation channel connected through the relevant transition state is associated with a finite barrier, which in turn would prevent the metastable species in transforming to global minimum products. All the calculated results suggest that the HRgOH2 (+) species are stable enough with respect to all the dissociation channels, except the 2-body dissociation path (H3O(+) + Rg). Structure, harmonic vibrational frequencies, stability, and charge distribution of HRgOH2 (+) species as obtained using density functional theory, second order Mo̸ller-Plesset perturbation theory, and coupled-cluster theory based methods are reported in this work. A possibility of existence of new species through insertion of a rare gas atom in hydronium ion resulting into HRgOH2 (+) cation (Rg = He, Ar, Kr, and Xe) has been explored by using various ab initio quantum chemical techniques.
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