From cluster to crystal: Ab initio calculations of the OH− frequency in lithium hydroxide monohydrate

doi:10.1016/0301-0104(92)80060-9

Chemical Physics

Volume 159, Issue 1, 1 January 1992, Pages 67-73

https://doi.org/10.1016/0301-0104(92)80060-9 Get rights and content

Abstract

The fundamental OH stretching frequency of the OH⁻ ion in crystalline LiOH·H₂O has been calculated by ab initio methods at the MP2 level. The experimental and calculated wavenumbers are 3575 and 3602 cm⁻¹, respectively. This frequency is shown to result from a delicate balance of several important interactions between the OH⁻ ion and its surroundings: the two cations in the (Li⁺)₂·OH⁻ cluster produce an upshift of 75 cm⁻¹ with respect to the isolated ion, while the whole nearest-neighbour cluster, (Li⁺)₂(H₂O)₂·OH⁻·OH⁻, gives a frequency downshift of −570 cm⁻¹. The crystal field outside the nearest-neighbour produces an upshift of 610 cm⁻¹. This behaviour conforms well with the frequency versus field correlation curves calculated for simple hydroxide point charge complexes.

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Cited by (12)

Synthesis of Li-Al layered double hydroxides via a mechanochemical route
2016, Applied Clay Science
Citation Excerpt :
The sample prepared at 1/2 exhibited a typical Li–Al LDH infrared pattern (Lin et al., 2010) with no other infrared bands from impurities. On the other hand, infrared bands around 3622 cm− 1 observed in the spectrum of 0.5/2 sample and bands positioned at 3566 cm− 1, 1004 cm− 1 and 866 cm− 1 observed from the spectrum of 2/2 sample were attributed to gibbsite (Alex et al., 2014) and lithium hydroxide monohydrate (Hase, 1980; Hermansson, 1992) respectively. The results confirmed that the optimal molar ratio was consistent with the molecular formula of Li–Al LDH, confirmed by XRD analysis.
In this study, we introduced a solvent-free mechanochemical route to synthesize Li–Al layered double hydroxide through a two-step grinding of LiOH and Al(OH)₃, in which the mixture powder with Li/Al molar ratio at 1/2 was first dry ground for 2 h and then wet ground for another 1 h with water addition without any heating operation. The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The products possessed highly crystalline of Li–Al LDH phase with no evident impure phases, presenting an easy and effective preparation of Li–Al LDH by using solvent-free mechanochemical approach.
The vibrating hydroxide ion in water
2011, Chemical Physics Letters
The OH⁻ ion in water is studied using a CPMD/BLYP + QM_electronic + QM_vibrational approach. The ion resides in a cage of water molecules, which are H-bonded among each other, and pinned by H-bonding to the ion’s O atom. The water network keeps the ‘on-top’ water in place, despite the fact that this particular ion-water pair interaction is non-binding. The calculated OH⁻ vibrational peak maximum is at ∼3645 cm⁻¹ (experiment ∼3625 cm⁻¹) and the shift with respect to the gas-phase is ∼ +90 cm⁻¹ (experiment +70 cm⁻¹). The waters molecules on each side of the ion (O and H) induce a substantial OH⁻ vibrational blueshift, but the net effect is much smaller than the sum. A parabolic ‘frequency-field’ relation qualitatively explains this non-additivity. The calculated ‘in-liquid’ ν(OH⁻) anharmonicity is 85 cm⁻¹.
OH bonds in electric fields: electron densities and vibrational frequency shifts
1995, Chemical Physics Letters
The changes in the electron density distribution caused by varying the OH bond length for HDO and OH⁻ in uniform electric fields are investigated and related to the frequency shifts for the uncoupled O-H stretching vibration. Numerical integration of difference density maps, Δϱ=ϱ(r_OH+ Δr_OH) -ϱ(rOH), reproduces the electronic contribution to δμ,_∥^total/ δr_OH, if the integration is carried out to a distance of ≈3.5 Å from the O atom. The frequency shift δν is proportional to $−E_{∥} × [d μ_{∥}^{permanent} (r_{oH}) /dr_{OH}] - 12 E_{∥},[δμ_{∥}^{induced} (E_{∥}, r_{OH})/δr_{OH}]$ and electron density maps corresponding to the electronic part of these terms are presented. Experimentally it has been found that the OH⁻ ion shows a frequency upshift when bound in a moderately strong field, while water molecules show a downshift. The electron density maps show why dμ_∥^permanent(roH) /dr_OH is positive for HDO and negative for OH ⁻, resulting in a downshift for bound water an an upshift for bound OH⁻. For positive fields, δμ_∥^induced/ δr_oH is positive for both HDO and OH ⁻ and gives a downshift contribution.
Non-additivity of OH frequency shifts in ion-water systems
1995, Chemical Physics Letters
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From cluster to crystal: Ab initio calculations of the OH− frequency in lithium hydroxide monohydrate

Abstract

J. Mol. Struct.

J. Chem. Phys.

Acta Crystallogr. Sect. C

J. Chem. Phys.

J. Chem. Phys.

Inorg. Chem.

Phys. Rev.

From cluster to crystal: Ab initio calculations of the OH⁻ frequency in lithium hydroxide monohydrate