Abstract
A supermolecule-continuum approach with water clusters up to n = 16 H2O molecules has been used to predict the absolute hydration free energies at 298 K (ΔGhyd) of both hydrogen (H•) and hydride (H-) to be 4.6 ± 1 and -78 ± 3 kcal/mol, respectively. These values are combined with a high accuracy prediction of the gas-phase electron affinity (ΔGgas,298K = -16.9 kcal/mol) to determine the aqueous electron affinity of H•of 99.5 ± 3 kcal/mol, which yields a reduction potential for H•vs SHE of -0.03 ± 0.15 V. This value is in agreement within 0.2 V with most estimates obtained using a wide variety of approaches. These results can be used to improve the absolute hydricity scale in water which provides additional insights into how a putative hydride interacts with solvent but do not change the ability to predict the relative reactivity of two species using relative hydricity scales.
Original language | English |
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Pages (from-to) | 6084-6095 |
Number of pages | 12 |
Journal | Journal of Physical Chemistry A |
Volume | 124 |
Issue number | 29 |
DOIs | |
Publication status | Published - Jul 23 2020 |
ASJC Scopus subject areas
- Physical and Theoretical Chemistry