Proton and electron transfers in O•H•O and C•H•O hydrogen-bridged ions: their role in the dissociation chemistry of ionized acetol, CH3C(=O)CH2OH•+

1996 ◽  
Vol 74 (6) ◽  
pp. 1078-1087 ◽  
Author(s):  
Paul J.A. Ruttink ◽  
Peter C. Burgers ◽  
Johan K. Terlouw
Keyword(s):  
Charge Transfer ◽  
Ab Initio ◽  
Hydrogen Transfer ◽  
Valence Bond ◽  
Radical Cations ◽  
Low Energy ◽  
Ion Molecule Reactions ◽  
Proton Transfers ◽  
Dissociation Chemistry ◽  
A Charge

Low-energy acetol ions CH3C(=O)CH2OH•+, 1, dissociate to CH3C(H)OH+ and HC=O• by a double hydrogen transfer (DHT), a common reaction among oxygen-containing radical cations. Recent experimental work has shown that the isotopologue CH3C(=O)CH2OD•+ specifically loses HC=O• to produce CH3C(D)OH+. This finding refutes an earlier postulated attractive mechanism based on the behaviour of 1 in ion-molecule reactions. Using ab initio MO calculations (at the CEPA//RHF/DZP level of theory complemented with valence bond (VB) methods), a low-energy pathway was traced that may explain all of the available experimental observations. It is shown that the unimolecular chemistry of 1 can be understood in terms of two proton transfers, taking place in intermediate O•H•O and C•H•O bonded hydrogen-bridged radical cations. The two protons originate from the same moiety and a charge transfer complex is therefore implicated and shown to be involved. These concepts of proton and charge transfer may well be more generally applicable and they do correctly predict the unimolecular chemistry of ionized acetoin, CH3C(=O)CH(CH3)OH•+ and related α-ketols. Key words: ab initio calculations, hydrogen-bridged ions.

Molecular Calculations of Interplanar Electronic Interactions in a Ybacu2O6+δ Cluster as a Function of the Oxygen Concentration.

1990 ◽  
Vol 209 ◽  
Author(s):  
J. A. Cogordan ◽  
L. E. Sansores ◽  
A. A. Valladares
Keyword(s):  
Charge Transfer ◽  
Ab Initio ◽  
Population Analysis ◽  
Oxygen Stoichiometry ◽  
Mulliken Population Analysis ◽  
Mulliken Population ◽  
Electronic Interactions ◽  
A Charge ◽  
Molecular Calculations ◽  
Scf Calculations

ABSTRACTMolecular ab initio SCF calculations on a cluster formed by Y, Cu(2)-O(2)-O(3) plane, Ba-O(1) plane and Cu(1)-O(4) chains are reported. The computations were performed for five different sets of lattice parameters of YBACu2O6+δ Each of these sets correspond to a values of the oxygen stoichiometry. Mulliken population analysis results show a charge transfer to the Cu(2)-O(2)-O(3) plane when the oxygen stoichiometry is increased from six to seven.

Ab initio study of charge transfer in low-energy collisions ofSi4+with helium

1997 ◽  
Vol 55 (2) ◽  
pp. 1064-1068 ◽  
Author(s):  
P. C. Stancil ◽  
B. Zygelman ◽  
N. J. Clarke ◽  
D. L. Cooper
Keyword(s):  
Charge Transfer ◽  
Ab Initio ◽  
Low Energy ◽  
Ab Initio Study

In-crystal ionic polarizabilities derived by combining experimental and ab initio results

1985 ◽  
Vol 398 (1815) ◽  
pp. 377-393 ◽  
Keyword(s):  
Refractive Index ◽  
Charge Transfer ◽  
Ab Initio ◽  
Empirical Model ◽  
Ionic Polarizability ◽  
Model Calculations ◽  
Ionic Solids ◽  
A Charge ◽  
Refractive Index Data ◽  
Environmental Dependence

It is shown that an empirical model of in-crystal polarizabilities must incorporate the environmentally induced variation of anion polarizabilities. Those of s 2 and p 6 cations can be taken to be constant. Such a model is combined with the ab initio calculation of small cation polarizabilities to extract the polarizabilities of Rb + , Cs + , Tl + , Sr 2+ , Ba 2+ and Pb 2+ from experimental refractive index data. The deficiencies of previous estimates are discussed. The function describing the environmental dependence of halide polarizabilities is found to be transferable between different crystal structures. This does not hold for chalcogenide anions. It is shown that the polarizabilities of d 10 cations are very sensitive to environment. The anisotropy of the purely electrostatic environment increases the polarizability of Ag + in AgF by 4% while model calculations suggest a much larger increase from anisotropic overlap effects. A comparison of the relative merits of an ionic polarizability and a charge-transfer picture of polarization in ionic solids is found to favour the former description.

An ab initio and experimental study of vibrational effects in low energy O++C2H2 charge-transfer collisions

2001 ◽  
Vol 115 (7) ◽  
pp. 3184-3194 ◽  
Author(s):  
Kaori Fukuzawa ◽  
Toshio Matsushita ◽  
Keiji Morokuma ◽  
Dale J. Levandier ◽  
Yu-hui Chiu ◽  
...  
Keyword(s):  
Experimental Study ◽  
Charge Transfer ◽  
Ab Initio ◽  
Low Energy

scholarly journals Trifluoromethyl-substituted tetrathiafulvalenes

2015 ◽  
Vol 11 ◽  
pp. 647-658 ◽  
Author(s):  
Olivier Jeannin ◽  
Frédéric Barrière ◽  
Marc Fourmigué
Keyword(s):  
Charge Transfer ◽  
Absorption Band ◽  
Cation Radical ◽  
Radical Cations ◽  
Oxidation Potential ◽  
Low Energy ◽  
Charge Transfer Complexes ◽  
Mesomeric Effect ◽  
Oxidation Potentials ◽  
Homo Lumo

A series of tetrathiafulvalenes functionalized with one or two trifluoromethyl electron-withdrawing groups (EWG) is obtained by phosphite coupling involving CF3-substituted 1,3-dithiole-2-one derivatives. The relative effects of the EWG such as CF3, CO2Me and CN on the TTF core were investigated from a combination of structural, electrochemical, spectrochemical and theoretical investigations. Electrochemical data confirm the good correlations between the first oxidation potential of the TTF derivatives and the σmeta Hammet parameter, thus in the order CO2Me < CF3 < CN, indicating that, in any case, the mesomeric effect of the substituents is limited. Besides, crystal structure determinations show that the deformation of the unsymmetrically substituted dithiole rings, when bearing one, or two different EWG, and attributed to the mesomeric effect of ester or nitrile groups, is not notably modified or counter-balanced by the introduction of a neighboring trifluoromethyl group. DFT calculations confirm these observations and also show that the low energy HOMO–LUMO absorption band found in nitrile or ester-substituted TTFs is not found in TTF-CF3, where, as in TTF itself, the low energy absorption band is essentially attributable to a HOMO→LUMO + 1 transition. Despite relatively high oxidation potentials, these donor molecules with CF3 EWG can be involved in charge transfer complexes or cation radical salts, as reported here for the CF3-subsituted EDT-TTF donor molecule. A neutral charge transfer complex with TCNQ, (EDT-TTF-CF3)2(TCNQ) was isolated and characterized through alternated stacks of EDT-TTF-CF3 dimers and TCNQ in the solid state. A radical cation salt of EDT-TTF-CF3 is also obtained upon electrocrystallisation in the presence of the FeCl4 − anion. In this salt, formulated as (EDT-TTF-CF3)(FeCl4), the (EDT-TTF-CF3)+• radical cations are associated two-by-two into centrosymmetric dyads with a strong pairing of the radical species in a singlet state.

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