The electron distribution of the hydroxide ion in lithium hydroxide

Abstract

Analysis of recently published X-ray and neutron diffraction data for LiOH reveals that there are pronounced non-spherical deformations of the electrondensity about the oxygen pseudo-atom. Comparison with a theoretical calculation of the electron density for the isolated hydroxide ion shows that these deformations are due to 7r-like bonding of the oxygen to the neighbouring hydrogen pseudo-atom. The observed features have shapes consistent with the non-spherical electron distribution of an isolated hydroxide ion undergoing rigid-body libration and translation. It is shown that an important effect of the rigid-body libration is a reversal in sign of the effective quadrupole component of the oxygen pseudo-atom electron density.

Lithium Hydroxide Phase Transition under High Pressure: An Ab Initio Molecular Dynamics Study

“…[26,27] In the layered structure, shown in Figure 1, the separation among the hydroxyl groups (and in particular between the intermolecular O···D distances) is large, and no hydrogen bond is formed. As a matter of fact, in the infrared and Raman spectra, the OÀD stretching mode is observed as a sharp peak with a tiny splitting ( % 10 cm…”

“…Under ambient conditions, lithium hydroxide crystallizes in the tetragonal space group P4/nmm with two asymmetric units per cell. [26,27] In the layered structure, shown in Figure 1, the separation among the hydroxyl groups (and in particular between the intermolecular O···D distances) is large, and no hydrogen bond is formed. As a matter of fact, in the infrared and Raman spectra, the OÀD stretching mode is observed as a sharp peak with a tiny splitting ( % 10 cm À1 ) between the g and u factor group components.…”

“…[23][24][25] The crystal exhibits a stable phase under ambient conditions (phase II) that has been fully characterized as a layered structure with the Li + cations tetrahedrally coordinated to the oxygen atoms of the hydroxyl groups. [26,27] The latter are not involved in hydrogen bonds. At ambient pressure, a transition has been observed to occur at 648 K (phase I).…”

“…[21,40,41] Starting from the experimental structure [26,27] of lithium hydroxide, a first MTD simulation was conducted at ambient temperature and pressure to ascertain if the method was indeed capable of identifying the available metastable states. The volume of the cell box was monitored along the simulation run, and its evolution is displayed in Figure 2.…”

2D calculation of anharmonic OH vibrations in a layered hydroxide crystal

“…LiOH is the sample crystal used in the present study. X-ray and neutron diffraction studies [2][3][4] have shown that this layered structure contains neutral anion-cation-anion sheets, where the OH − groups in neighboring sheets are oriented towards each other in an antiparallel fashion ͑Fig. 1͒.…”