scholarly journals Vibrational spectroscopic and quantum theoretical study of host-guest interactions in clathrates: I. Hofmann type clathrates

2000 ◽  
Vol 65 (5-6) ◽  
pp. 417-430 ◽  
Author(s):  
Biljana Minceva-Sukarova ◽  
Liljana Andreeva ◽  
Ljupco Pejov ◽  
Vladimir Petrusevski
Keyword(s):  
Guest Molecule ◽  
Theoretical Study ◽  
Far Infrared ◽  
Spectroscopic Properties ◽  
Host Lattice ◽  
Hydrogen Atoms ◽  
Crystalline Field ◽  
Theoretical Approaches ◽  
Guest Species ◽  
Insight Into

Hofmann type clatharates are host-guest compounds with the general formula M(NH3)2M'(CN)4.2G, in which M(NH3)2M'(CN)4 is the host lattice and G is benzene, the guest molecule. In previous studies, host-guest interactions have been investigated by analyzing the RT and LNT vibrational (infrared, far infrared and Raman) spectra of these clathrates. All the observed changes in the vibrational spectra of these clathrates are referred to a host-guest interaction originating from weak hydrogen bonding between the ammonia hydrogen atoms from the host lattice and the p electron cloud of the guest (benzene) molecules. In order to obtain an insight into the relative importance of the local crystalline field vs. the anharmonicity effects on the spectroscopic properties of the guest species upon enclathration, as well as to explain the observed band shifts and splittings, several quantum theoretical approaches are proposed.

Ab initio Study of the Potential Curves for CO (X1Σ+), CH (X2Π) and OH (X2Π)

1994 ◽  
Vol 59 (6) ◽  
pp. 1241-1250 ◽  
Author(s):  
Martina Bittererová ◽  
Stanislav Biskupič ◽  
Hans Lischka ◽  
Viliam Klimo
Keyword(s):  
Potential Energy ◽  
Energy Surface ◽  
Spectroscopic Properties ◽  
Ab Initio Study ◽  
Theoretical Approaches ◽  
Functional Methods ◽  
Diatomic Systems ◽  
Insight Into ◽  
Selection Of ◽  
Potential Curves

Calculations on spectroscopic properties of the diatomic systems CO, CH, and OH have been carried out by the multiconfiguration SCF, single reference and multireference single and double excitation CI, and average coupled pair functional methods. An evaluation of the different theoretical approaches is performed in order to get better insight into the selection of appropriate procedures for the calculation of the potential energy surface of the H + CO system.

scholarly journals Molecular Hydrogen as a Lewis Base in Hydrogen Bonds and Other Interactions

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3294 ◽  
Author(s):  
Sławomir J. Grabowski
Keyword(s):  
Hydrogen Bonds ◽  
Molecular Hydrogen ◽  
Spectroscopic Properties ◽  
Lewis Base ◽  
Basis Set ◽  
Orbital Method ◽  
Topological Parameters ◽  
Theoretical Approaches ◽  
Strength Of Interaction ◽  
Moller Plesset

The second-order Møller–Plesset perturbation theory calculations with the aug-cc-pVTZ basis set were performed for complexes of molecular hydrogen. These complexes are connected by various types of interactions, the hydrogen bonds and halogen bonds are most often represented in the sample of species analysed; most interactions can be classified as σ-hole and π-hole bonds. Different theoretical approaches were applied to describe these interactions: Quantum Theory of ‘Atoms in Molecules’, Natural Bond Orbital method, or the decomposition of the energy of interaction. The energetic, geometrical, and topological parameters are analysed and spectroscopic properties are discussed. The stretching frequency of the H-H bond of molecular hydrogen involved in intermolecular interactions is considered as a parameter expressing the strength of interaction.

Through-Space Transmission of 19F-13C Coupling Via an Intermediate Bond. An Experimental and Theoretical Study

1987 ◽  
Vol 40 (12) ◽  
pp. 1923 ◽  
Author(s):  
ID Rae ◽  
ID Rae ◽  
A Staffa ◽  
A Staffa ◽  
AC Diz ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Lone Pair ◽  
Electron Excitation ◽  
Carbonyl Groups ◽  
Polarization Propagator ◽  
Close Proximity ◽  
Fermi Contact ◽  
Intramolecular Hydrogen ◽  
Intermediate Bond ◽  
Insight Into

In order to obtain a deeper insight into the title effect, several compounds with an F atom very close to a C-H of a nearby functional group were synthesized and the relevant couplings measured. The most conspicuous case was that of 8-fluoro-2-hydroxynaphthalene-1-carbaldehyde where a close proximity between the F and H atoms is the result of fluorine-oxygen repulsion and the formation of an intramolecular hydrogen bond between the hydroxyl and carbonyl groups. The experimental four-bond J(F,CHO) coupling is 26.2 Hz. A compound very similar to this one, but without the OH group, was chosen on which to perform a polarization propagator analysis of the through-space (TS) coupling pathways, at the RPA-INDO level. The expression for the TS coupling in terms of the projected polarization propagator and perturbators was numerically analysed. It is found that this coupling is completely dominated by a TS component of the Fermi contact (FC) term, the main features of which are: ( i ) It decays exponentially with the F-H distance; (ii) Its main contribution comes from an electron excitation involving the F lone-pair, the C-H bond of the CHO moiety and its corresponding antibonding orbital;(iii) The π-type lone-pair does not contribute to the TS coupling pathway of the FC term.

Where Are the Hydrogen Atoms in [(η5-C5H5)(PH3)2W(H2SiMe2)]+? A Theoretical Study

2004 ◽  
Vol 23 (12) ◽  
pp. 2944-2948 ◽  
Author(s):  
Krishna K. Pandey ◽  
Matthias Lein ◽  
Gernot Frenking
Keyword(s):  
Theoretical Study ◽  
Hydrogen Atoms

A systematic neutron reflectometry study on hydrogen absorption in thin Mg1-xAlx alloy films Special issue on Neutron Scattering in Canada.

2010 ◽  
Vol 88 (10) ◽  
pp. 723-728 ◽  
Author(s):  
H. Fritzsche ◽  
E. Poirier ◽  
J. Haagsma ◽  
C. Ophus ◽  
E. Luber ◽  
...  
Keyword(s):  
Hydrogen Absorption ◽  
Scattering Length ◽  
Catalyst Layer ◽  
Neutron Reflectometry ◽  
Hydrogen Distribution ◽  
Hydrogen Atoms ◽  
Alloy Films ◽  
Negative Scattering Length ◽  
Insight Into ◽  
Optimum Alloy

In this article, we show how neutron reflectometry (NR) can provide deep insight into the absorption and desorption properties of commercially promising hydrogen storage materials. NR benefits from the large negative scattering length of hydrogen atoms, which changes the reflectivity curve substantially, so that NR can determine not only the total amount of stored hydrogen but also the hydrogen distribution along the film normal, with nanometer resolution. To use NR, the samples must have smooth surfaces, and the film thickness should range between 10 and 200 nm. We performed a systematic study on thin Mg1–xAlx alloy films (x = 0.2, 0.3, 0.4, 0.67) capped with a Pd catalyst layer. Our NR experiments showed that Mg0.7Al0.3 is the optimum alloy composition with the highest amount of stored hydrogen and the lowest desorption temperature. All the thin films expand by about 20% because of hydrogen absorption, and the hydrogen is stored only in the MgAl layer with no hydrogen content in the Pd layer.

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