The anomalous gas phase acidity of ethyl fluoride. An abinitio investigation of the importance of hydrogen bonding between F− and sp2 and sp C—H bonds

1985 ◽  
Vol 63 (3) ◽  
pp. 708-715 ◽  
Author(s):  
M. Roy ◽  
T. B. McMahon
Keyword(s):  
Gas Phase ◽  
Quantum Chemical ◽  
Molecular Formula ◽  
Stable Isomer ◽  
Structural Isomers ◽  
Proton Abstraction ◽  
Gas Phase Acidity ◽  
Chemical Techniques ◽  
Gas Phase Ion ◽  
Hydrogen Bonded

Abinitio quantum chemical techniques have been used to investigate the structures and energetics of a number of hydrogen bonded adducts of F− and C—H bonds associated with unsaturated systems as well as their structural isomers. Examination of the possible species of molecular formula C2H4F− reveals that the most stable isomer is a hydrogen bonded adduct of F− and ethylene, while the classical β-fluoroethyl carbanion is found not to be bound with respect to dissociation into F− + C2H4. Similar examination of C2H2F− isomers shows that a hydrogen bonded F−–acetylene adduct is the most stable structure, however, the remaining α and β-fluorovinyl carbanions are found to be bound with respect to F− + C2H2. These results are used to explain the unusual gas phase acidities of ethylfluoride and vinylfluoride. Calculations on C3H4F− isomers show the hydrogen bonded adduct of F− and allene to be more stable than the classical 2-fluoropropenyl anion and on C2H2FO− isomers show the enolate of acetyl fluoride to be more stable than the hydrogen bonded adduct of F− and ketene. These latter results are used to explain the gas phase ion molecule reactivities of C3H4F− (predominantly F− transfer) and C2H2FO− (proton abstraction).

The fluoroformate ion, FCO2−. An ion cyclotron resonance study of the gas phase Lewis acidity of carbon dioxide and related isoelectronic species

1978 ◽  
Vol 56 (8) ◽  
pp. 1069-1074 ◽  
Author(s):  
Terrance Brian McMahon ◽  
Colleen Joan Northcott
Keyword(s):  
Carbon Dioxide ◽  
Gas Phase ◽  
Lewis Acidity ◽  
Ion Cyclotron Resonance ◽  
Dissociation Energies ◽  
Ion Molecule Reactions ◽  
Gas Phase Acidity ◽  
Gas Phase Ion ◽  
Carbonyl Fluoride

The gas phase ion molecule reactions of a number of potential fluoride donors with carbon dioxide and carbonyl fluoride have been studied. By determination of preferential directions of fluoride transfer the fluoride affinities of carbon dioxide and carbonyl fluoride have been bracketed and found to be 33 ± 3 kcal/mol and 35 + 3 kcal/mol respectively. In addition, from gas phase acidity studies of acetyl fluoride and 2-fluoropropene the fluoride affinities of ketene and allene have been calculated to be 38 ± 2 kcal/mol and 15 ± 2 kcal/mol respectively. The order of fluoride affinities (Lewis acidities) of carbon dioxide, ketene, and allene have been examined and explained in terms of the electron affinities of the F—C(A)(B) species (A,B=O,CH2) and the C—F bond dissociation energies. These quantities have been estimated and the latter interpreted on the basis of the π bond energies of the three compounds.

The Enthalpies of Formation ofo-,m-, andp-Benzoquinone:  Gas-Phase Ion Energetics, Combustion Calorimetry, and Quantum Chemical Computations Combined

2005 ◽  
Vol 127 (16) ◽  
pp. 6116-6122 ◽  
Author(s):  
Alireza Fattahi ◽  
Steven R. Kass ◽  
Joel F. Liebman ◽  
M. Agostinha R. Matos ◽  
Margarida S. Miranda ◽  
...  
Keyword(s):  
Gas Phase ◽  
Quantum Chemical ◽  
Combustion Calorimetry ◽  
Enthalpies Of Formation ◽  
Gas Phase Ion ◽  
Quantum Chemical Computations

scholarly journals Study of 1st and 2nd order nonlinear optical( NLO ) properties of chalcone derivative 3-(4-chlorophenyl)-1-(pyridin-3-yl) prop-2-en-1-one using quantum chemical techniques

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Ram Kumar Tiwari ◽  
Rakesh Kumar Singh
Keyword(s):  
Gas Phase ◽  
Quantum Chemical ◽  
Density Functional ◽  
Nonlinear Optical ◽  
Visible Range ◽  
Functional Theory ◽  
Nlo Properties ◽  
Nonlinear Properties ◽  
Chalcone Derivative ◽  
Chemical Techniques

The chalcone derivative 3-(4-chlorophenyl)-1-(pyridin-3-yl) prop-2-en-1-one has been investigated by quantum chemical calculations carried out using density functional theory. The nonlinear optical properties of the molecule are studied in the gas phase. The study shows that the molecule is transparent in the entire visible range. The effect of position of functional groups on the mobility of charges in push-pull type of structure has been discussed. Nonlinear properties of the molecule show that the molecule has a potential candidature for organic NLO material.

Notizen: Quantum Chemical Investigations on the Structure of the Gas Phase Ion Solvates M+(DMF-CH3+)

1975 ◽  
Vol 30 (12) ◽  
pp. 1792-1793
Author(s):  
B. M. Rode ◽  
R. Ahlrichs
Keyword(s):  
Charge Transfer ◽  
Complex Formation ◽  
Ab Initio ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Basis Sets ◽  
Polarization Effects ◽  
Stabilization Energies ◽  
Gas Phase Ion ◽  
Scf Calculations

Abstract The structure of the dimethylformamide fragment (DMF-CH3+) and its complexes with Li+ and Na+ being observed in low pressure gas phase solvation has been investigated by means of ab initio SCF calculations with two different basis sets. Stabilization energies, charge transfer and polarization effects upon complex formation are discussed.

Structural Isomers of C70

1992 ◽  
Vol 270 ◽  
Author(s):  
Krishnan Raghavachari
Keyword(s):  
Ab Initio ◽  
Ground State ◽  
Quantum Chemical ◽  
Energy Difference ◽  
Structural Isomers ◽  
Chemical Techniques ◽  
Isomeric Structures

ABSTRACTAlternative isomeric structures of C70 have been investigated using semiempirical and ab initio quantum chemical techniques. As in the case of C60, these isomers are characterized by the presence of pentagonal rings adjacent to each other. The lowest energy alternative isomer of C70 has only one pair of edge-sharing pentagons and lies ≈ 1.4 eV higher in energy than the ground state. This energy difference is smaller than that for the lowest energy alternative isomer of C60 which contains two pairs of adjacent pentagons and lies ≈ 2.0 eV higher in energy than its ground state.

The gas phase hydrogen-bonded dimers of HOCl: A high-level quantum chemical study

2009 ◽  
Vol 110 (8) ◽  
pp. 1489-1499 ◽  
Author(s):  
Hossein Roohi ◽  
Ali-Reza Nowroozi ◽  
Fazlola Eshghi
Keyword(s):  
Gas Phase ◽  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
High Level ◽  
Hydrogen Bonded

An investigation of the ion–molecule interactions of protonated glycine with ammonia by high pressure mass spectrometry and ab initio calculations

2005 ◽  
Vol 83 (11) ◽  
pp. 1978-1993 ◽  
Author(s):  
Ronghu Wu ◽  
Terry B McMahon
Keyword(s):  
Mass Spectrometry ◽  
High Pressure ◽  
Potential Energy ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Gas Phase ◽  
Energy Surface ◽  
Stable Isomer ◽  
Molecule Interactions ◽  
Gas Phase Ion

The thermochemistry of gas-phase ion molecule interactions and the structures of various clusters between protonated glycine (GlyH+), glycine, and ammonia have been studied by high pressure mass spectrometry (HP-MS) and ab initio calculations. For the association reactions of GlyH+ with NH3, Gly(NH3)H+ with NH3, and (Gly)2H+ with NH3, the enthalpy changes experimentally determined are –23.2, –18.3, and –19.1 kcal mol–1 (1 cal = 4.184 J), respectively. For all clusters investigated, the measured binding enthalpies are in excellent agreement with those obtained from ab initio calculations at the B3LYP/6-311+G(d,p) level of theory. Different isomers of each of these clusters have been obtained and the corresponding binding energies have been computed. The potential energy surface for isomerization of the clusters of protonated glycine with ammonia has also been computed at the same level. For this cluster, the three most stable isomers all involve a proton transfer from protonated glycine to ammonia. According to the calculated potential energy surface, the barrier between GN4, the least stable isomer, and the most stable isomer (GN1) is 11.5 kcal mol–1 at 298 K. Thus, this isomerization will be facile given the exothermicity of the association reaction. Therefore, a statistical distribution of isomers will be present under thermal equilibrium conditions. Single point energy calculations at the MP2(full)/6-311++G(2d,2p)//B3LYP/6-311+G(d,p) level of theory reveal that the isomer GN2 in which glycine has a zwitterionic structure has the same energy as the most stable non-zwitterionic isomer GN1. NH4+ evidently may stabilize the zwitterionic structure of glycine. In contrast, N2H7+ and GlyH+ are not as effective in stabilizing the zwitterionic structure of glycine. This likely results from the more localized charge in NH4+ giving rise to stronger hydrogen bonds with the carboxylate moiety of zwitterionic glycine. This conjecture is supported by the computational results.Key words: high pressure mass spectrometry, glycine, gas-phase ion thermochemistry, ab initio calculations, cluster structure.

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