A COMPUTATIONAL STUDY OF BINARY GAS-PHASE COMPLEXES OF PROPARGYLIMINE, A RECENTLY DETECTED MOLECULE IN THE INTERSTELLAR MEDIUM, WITH THE MOLECULES HF AND H2O

In the present work, a computational study is performed in order to clarify the possible magnetic nature of gold. For such purpose, gas phase Au2 (zero charge) is modelled, in order to calculate its gas phase formation enthalpy. The calculated values were compared with the experimental value obtained by means of Knudsen effusion mass spectrometric studies [5]. Based on the obtained formation enthalpy values for Au2, the compound with two unpaired electrons is the most probable one. The calculated ionization energy of modelled Au2 with two unpaired electrons is 8.94 eV and with zero unpaired electrons, 11.42 eV. The difference (11.42-8.94 = 2.48 eV = 239.29 kJmol-1), is in very good agreement with the experimental value of 226.2 ± 0.5 kJmol-1 to the Au-Au bond7. So, as expected, in the specie with none unpaired electrons, the two 6s1 (one of each gold atom) are paired, forming a chemical bond with bond order 1. On the other hand, in Au2 with two unpaired electrons, the s-d hybridization prevails, because the relativistic contributions. A molecular orbital energy diagram for gas phase Au2 is proposed, explaining its paramagnetism (and, by extension, the paramagnetism of gold clusters and nanoparticles).

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2-Deoxyribose Radicals in the Gas Phase and Aqueous Solution. Transient Intermediates of Hydrogen Atom Abstraction from 2-Deoxyribofuranose

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20051769 ◽

2005 ◽

Vol 70 (11) ◽

pp. 1769-1786 ◽

Cited By ~ 4

Author(s):

Luc A. Vannier ◽

Chunxiang Yao ◽

František Tureček

Keyword(s):

Aqueous Solution ◽

Hydrogen Atom ◽

Gas Phase ◽

Computational Study ◽

Hydrogen Atom Abstraction ◽

Oh Radical ◽

Free Energies ◽

Intramolecular Hydrogen ◽

Solvation Free Energies ◽

Transient Intermediates

A computational study at correlated levels of theory is reported to address the structures and energetics of transient radicals produced by hydrogen atom abstraction from C-1, C-2, C-3, C-4, C-5, O-1, O-3, and O-5 positions in 2-deoxyribofuranose in the gas phase and in aqueous solution. In general, the carbon-centered radicals are found to be thermodynamically and kinetically more stable than the oxygen-centered ones. The most stable gas-phase radical, 2-deoxyribofuranos-5-yl (5), is produced by H-atom abstraction from C-5 and stabilized by an intramolecular hydrogen bond between the O-5 hydroxy group and O-1. The order of radical stabilities is altered in aqueous solution due to different solvation free energies. These prefer conformers that lack intramolecular hydrogen bonds and expose O-H bonds to the solvent. Carbon-centered deoxyribose radicals can undergo competitive dissociations by loss of H atoms, OH radical, or by ring cleavages that all require threshold dissociation or transition state energies >100 kJ mol-1. This points to largely non-specific dissociations of 2-deoxyribose radicals when produced by exothermic hydrogen atom abstraction from the saccharide molecule. Oxygen-centered 2-deoxyribose radicals show only marginal thermodynamic and kinetic stability and are expected to readily fragment upon formation.

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A vibrational spectroscopic and computational study of the structures of protonated imidacloprid and its fragmentation products in the gas phase

Physical Chemistry Chemical Physics ◽

10.1039/d0cp06069k ◽

2021 ◽

Vol 23 (5) ◽

pp. 3377-3388

Author(s):

Kelsey J. Menard ◽

Jonathan Martens ◽

Travis D. Fridgen

Keyword(s):

Computational Chemistry ◽

Gas Phase ◽

Vibrational Spectroscopy ◽

Computational Study ◽

Unimolecular Decomposition ◽

Decomposition Products

Vibrational spectroscopy and computational chemistry studies were combined with the aim of elucidating the structures of protonated imidacloprid (pIMI), and its unimolecular decomposition products.

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Abundances in the Gaseous Galactic Halo

Highlights of Astronomy ◽

10.1017/s1539299600020049 ◽

1998 ◽

Vol 11 (1) ◽

pp. 86-89

Author(s):

Ulysses J. Sofia

Keyword(s):

Interstellar Medium ◽

Gas Phase ◽

High Velocity ◽

Galactic Halo ◽

Solar Neighborhood ◽

Local Interstellar Medium ◽

The Galaxy ◽

Metal Abundances ◽

High Velocity Clouds

Abstract The well measured gas-phase abundances in the low halo suggest that this region of the Galaxy has total (gas plus dust) metal abundances which are close to those in the solar neighborhood. The gas-phase abundances in the halo are generally higher than those seen in the disk, however, this affect is likely due to the destruction of dust in the halo clouds. Observations of high velocity clouds (HVCs) in the halo suggest that these clouds have metal abundances which are substantially lower than those measured for the local interstellar medium. These determinations, however, are often of lower quality than those for the low halo because of uncertainties in the hydrogen abundances along the sightlines, in the incorporation of elements into dust, and in the partial ionization of the clouds.

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