Spectroscopic identification of a number of radiation—produced alkane radical cations

<div> <div> <div> <p>A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N- containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl) and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios and reaction efficiencies are reported. </p> </div> </div> </div>

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Acetylene Radical-Cations in Carbon-Carbon Bond Forming Reactio ns

Mini-Reviews in Organic Chemistry ◽

10.2174/1570193x14666170208101802 ◽

2017 ◽

Vol 14 (3) ◽

Cited By ~ 3

Author(s):

Aleksander V. Vasilyev

Keyword(s):

Radical Cations ◽

Carbon Bond ◽

Bond Forming ◽

Carbon Carbon Bond

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Properties and Reactivity of First and Second Row Hydrides. IV. Interactions Between Hydrides and Their Radical Ions

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19930001 ◽

1993 ◽

Vol 58 (1) ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Rudolf Zahradník

Keyword(s):

Radical Cations ◽

Stabilization Energy ◽

Hydrogen Atom Abstraction ◽

Type Ii ◽

Radical Ions ◽

Reaction Products ◽

Ion Molecule Reactions ◽

Heats Of Reaction ◽

Experimental Values ◽

Easy Differentiation

The energies and heats of ion-molecule reactions have been calculated (MP4/6-31G**//6-31G** or better level) and compared with the experimental values obtained from the heats of formation. Two main types of reactions have been studied: (i) AHn + AHn+• ↔ AHn+1+ + AHn-1• (A = C to F and Si to Cl), (ii) AHn + BHm+• ↔ AHn+1+ + BHm-1• or AHn-1+• + BHm+1+ (A and B = C to F). In contrast to (i), processes of type (ii) permit easy differentiation between the proton transfer and hydrogen atom abstraction mechanisms. A third type of interaction involves reactions with radical anions (A = Li to F); comparison was made with analogous processes with radical cations. A brief comment is made about the influence of the level of computational sophistication on the energies and heats of reaction, as well as on the stabilization energy of a hydrogen bonded intermediate, a structure which is similar to that of the reaction products.

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Electrostatic effects on ionization equilibria: An MNDO study of proton and hydrogen transfer reactions of 4-fluorobutylamine

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19900001 ◽

1990 ◽

Vol 55 (1) ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Zdeněk Friedl ◽

Stanislav Böhm

Keyword(s):

Hydrogen Transfer ◽

Substituent Effects ◽

Radical Cations ◽

Transfer Reactions ◽

Protonated Forms ◽

Minor Part ◽

Bond Strengths ◽

Ionization Equilibria ◽

A Minor ◽

Gas Phase Basicities

The relative enthalpies of proton transfer δ ΔH0and homolytic bond strengths δDH0(B-H+) were calculated by the MNDO method for the sp and ap conformers of 4-flurobutylamine. The data obtained, along with the experimental gas phase basicities, are compared with the values predicted by the electrostatic theory. It is shown that the substituent polar effects FD on the basicities of amines are predominantly due to interactions in their protonated forms (X-B-H+) and/or radical-cations (X-B+.), those in the neutral species (X-B) playing a minor part. A contribution, which is considerably more significant in the sp conformer than in the ap conformer, arises probably also from substituent effects on the homolytic bond strength DH0(B-H+.

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A Combined ab initio and Density Functional Study of the Electronic Structure of Thymine and 2-Thiothymine Radicals

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20032322 ◽

2003 ◽

Vol 68 (12) ◽

pp. 2322-2334 ◽

Cited By ~ 1

Author(s):

Robert Vianello ◽

Zvonimir B. Maksić

Keyword(s):

Ab Initio ◽

Spin Density ◽

Density Functional ◽

Radical Cations ◽

Functional Study ◽

Theory Approach ◽

Functional Theory ◽

Adiabatic Ionization Potential ◽

Highest Occupied Molecular Orbital ◽

Positively Charged

The electronic and energetic properties of thymine (1) and 2-thiothymine (2) and their neutral and positively charged radicals are considered by a combined ab initio and density functional theory approach. It is conclusively shown that ionization of 1 and 2 greatly facilitates deprotonation of the formed radical cations thus making the proton transfer between charged and neutral precursor species thermodynamically favourable. The adiabatic ionization potential of 1 and 2 are analysed. It appears that ADIP(1) is larger than ADIP(2) by 10 kcal/mol, because of greater stability of the highest occupied molecular orbital (HOMO) of the former. It is also shown beyond any doubt that the spin density in neutral and cationic radical of 2 is almost exclusively placed on the σ-3p AO of sulfur implying that these two systems represent rather rare sigma-radicals. In contrast, the spin density of radicals of 1 is distributed over their π-network.

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