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Unexpected Solute Occupancy and Anisotropic Polarizability in Lewis Basic Solutions

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journal contribution
posted on 30.09.2019, 19:33 by Siyan Gao, Yongli Huang, Xi Zhang, Chang Q. Sun
Density functional computation revealed that in YOH solvation (Y = Li, Na, and K), the Y+ cation locates eccentrically at the interstitial hollow site to form the Y+·4H2O unit, and the hydroxyl adds an excessive electron lone pair “:” to form a OH·H2O unit where the hydroxide stays in the the center. The surrounding four oriented H2O neighbors interact with the Y+ through Y+ ↔ H+ repulsion and Y+:O2– attraction, causing the Y+ eccentric dislocation by some 0.80 Å. The “:” turns one O:H–O bond into the O: ⇔ :O super hydrogen bond by altering H2O·4H2O into HO·4H2O. The repulsive Y+ ↔ H+ enlarges its separation and the attractive Y+:O shortens itself, showing the anisotropic polarization of the Y+ cation. The anisotropic Y+ polarizability, O: ⇔ :O compressibility, and the H–O bond contraction of the solute OH distorts the solute bonding network and disperses the O:H–O segmental phonon frequencies, as confirmed spectroscopically.