Electronic effects and ring strain influences on the electron uptake by selenium‐containing bonds

Abstract

International audienceThe gas-phase electron attachment of thiaselena and diselena derivatives is investigated on model organic systems by ab initio calculations (level of theory MP2/DZP++). Electronic contributions favor the one-electron addition on selenium-containing compounds, with adiabatic electron affinities of 0.03, 0.24, and 0.43 eV, respectively, for dimethyldisulfide, dimethylselenenylsulfide, and dimethyldiselenide. This ensures the possibility of an excess electron binding on [BOND]Se[BOND]S[BOND] and [BOND]Se[BOND]Se[BOND] linkages. The so-formed radical anionic intermediates present a three-electrons two-centers 2c[BOND]3e bond, whose nature is confirmed by Mulliken spin densities and NBO analysis. They are stable towards dissociation, with a low barrier evaluated between about 25–60 kJ/mol. Cyclization strongly enhances dichalcogen propensity to fix an excess electron. Adiabatic electron affinities of a series of 1,2-thiaselena-cycloalkanes and 1,2-diselena-cycloalkanes are positive and range from 0.24 to 1.30 eV. This can be traced back to the release of ring strain energy upon one-electron addition: this geometrical effect is nevertheless less marked than for disulfide analogs. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 201

One‐electron addition on short‐loop selenylsulfide and diselenide‐linked biomolecules: From diethyldichalcogens to Grx3‐like selenopeptides

“…3(a)]: evolution is directed towards lenghtening only, which is justified by the universal dissymmetry of Morse curves. The latter can be found in Figure 4 in Reference [33]. In contrast, corresponding RA hemi-bonds exhibit much larger deviations, by up to 0.15 Å [n = 0 for dithia and selenylsulfide linkages, Fig.…”

“…The latter was generalized to selenylsulfide -S-Se-and diselenide -Se-Se-linkages [33]. Explicit treatment of electron correlation is mandatory for a correct evaluation of geometries and adiabatic electron affinities (AEAs) [34].…”

“…It is known that AEA in biomolecules is modulated upon cyclization and collective electrostatic components [31][32][33]39]. Both effects will be analyzed in "Contrasted Increase of Electron Affinities Upon Cyclization" and "Common Modulation Upon α-Helix Dipole" sections.…”

Electron Capture Dissociation of Disulfide, Sulfur–Selenium, and Diselenide Bound Peptides

“…Previously, Dumont et al [1] used ab initio calculations to investigate the gas-phase electron addition on selenium-containing organic compounds, dimethyldisulfide, dimethylseleneylsulfide, and dimethyldiselenide. It is found that selenium strongly enhances the electron Figure 2.…”

“…Previous studies have been mainly focused on using theoretical calculations to study the effects of electron capture on small diselenide compounds (XSeSeX'), such as CH 3 SeSeCH 3 , CH3SeSeOH, CH3SeSeF, and such [1,[32][33][34][35]. So, it is of interest to examine the ECD behavior of diselenide peptides compared with previous theoretical calculations, and also to examine the differences and similarities of the ECD fragmentation patterns among disulfide (S-S), sulfur-selenium (S-Se), and diselenide (Se-Se) peptides.…”