Proton affinity and gas-phase basicity of pyrogallol and phloroglucinol: a computational study

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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