Gennady L. Gutsev

The valence and dipole-bound states of the cyanomethide ion, CH2CN−

Abstract The electronic and geometrical structures of the cyanomethyl radical, CH 2 CN, and cyanomethide ion, CH 2 CN − , are investigated with the Hartree-Fock method, Moller-Plesset perturbation theory and coupled cluster theory. It is found that the lowest singlet and triplet dipole-bound states ( 1 B 1 and 3 B 1 ) of the anion correspond to a σ-attachment of the extra electron to the ground ( 2 B 1 , C 2v state of the CH 2 CN radical. The ground valence ( 1 A′, C s ) anionic state results from a π-attachment, which leads to some pyramidalization of the flat configuration of the neutral parent. The calculated electron affinities of CH 2 CN with respect to both anionic states are in good agreement with the experimental data.

Relationship between the dipole moments and the electron affinities for some polar organic molecules

Abstract The electronic and geometrical structures of fourteen polar molecules are investigated with the Hartree-Fock (HF) method and the second-order Moller-Plesset (MP2) perturbation theory. The molecules are: formaldehyde, H 2 CO, propanol, CH 3 CH 2 CHO, pivalaldehyde, (CH 3 ) 3 CCHO, butanal, CH 3 CH 2 CH 2 CHO, acetaldehyde, CH 3 CHO, 2-butanone, CH 3 CH 2 COCH 3 , trifluoromethylbenzene, C 7 H 5 F 3 , cyclohexanone, C 6 H 10 O, acetone, CH 3 COCH 3 , cyclopentanone, C 5 H 8 O, cyclobutanone, C 4 H 6 O, methylacrylonitrile, CH 2 CCH 3 CN, acrylonitrile, CH 2 CHCN, acetonitrile, CH 3 CN. The electron affinities corresponding to the formation of the dipole-bound states of the anions are calculated. For all the molecules considered, except formaldehyde, the molecules are found to be able to support dipole-bound states.

A theoretical study on the structure of acetonitrile (CH3CN) and its anion CH3CN

Abstract The electronic and geometrical structures of the CH3CN molecule and its anion CH3CN− are calculated at the UHF, UMP2, UMP4, CASSCF and CASPT2 levels of theory. The anion CH3CN− is confirmed to possess a dipole-bound state. The electron affinity (EA) of CH3CN is computed to be ≈ 6 meV. The potential energy surfaces (PES) of both the neutral and anionic species are computed as functions of the distance between carbon atoms of the CH3 and CN constituents. It is found that the neutral molecule possesses the avoiding crossing between two lowest singlet states having different dissociation limits, namely CH3(doublet) + CN(doublet) and CH3+(singlet) + CN−(singlet). The anionic PES is always lower than the neutral one and possesses an appreciable barrier of ≈ 0.8 eV at the distance range of 2.0–2.5 A between the CH3 and CN groups. This barrier separates the dipole-bounded and “normal” bound states of the CH3CN− anion. After passing the barrier there is a local minimum at the anion PES with respect to which the adiabatic EA of the neutral CH3CN molecule is negative of ≈ −1.6 eV.

The electronic and geometrical structure of aluminum fluoride anions AlF−n, n=1–4, and electron affinity of their neutral parents

The electronic and geometrical structure of AlF−, AlF−2, AlF−3, and AlF−4 as well as their neutral parents are determined at the unrestricted Hartree–Fock (UHF) and second‐order unrestricted Mo/ller–Plesset (UMP2) levels of theory. The results of the calculations are used for estimating the adiabatic electron affinity (E.A.) of the neutrals and fragmentation energies of both the neutrals and anions. All these characteristics were also recomputed using the UMP2/6‐31+G* geometry at the fourth‐order UMP4 level of theory. According to the results of the single‐, double, triple‐, and quadruple‐excitation fourth‐order Mo/ller–Plesset (MP4SDTQ) calculations, the AlF molecule in the ground state has no positive E.A., AlF2 possesses a rather high E.A. value of 1.90 eV, and AlF3 has a smaller E.A. of 0.93 eV, whereas the last member in the series AlF4 possesses an extremely high E.A. of 7.96 eV. Such a large value is related to high stability of the anion towards fragmentation opposite to the neutral AlF4 whose dis...

The structure of the CF−4 anion and the electron affinity of the CF4 molecule

The electronic and geometrical structure of the CF−4 anion and its neutral parent, CF4, are calculated with the second‐order Moller–Plesset perturbation theory. Several diffuse sp shells were added to the standard 6‐31+G* basis when calculating the potential energy surface of the CF4+e− system. It was found that the CF4 molecule does not attach an additional electron in the ground state, i.e., the molecule possesses a zero vertical electron affinity under the Born–Oppenheimer approximation. The optimized C3v and C2v configurations of the anion are transition states, whereas its Cs configuration corresponds to a local minimum and is thermodynamically stable by 20 kcal/mol. The CF4 molecule has the negative adiabatic electron affinity of −1.22 eV with respect to this configuration of the anion.