Is Se–Se bond cleavage the most favourable process in electron attachment to diselenides? The importance of asymmetry

Gámez, José A.; Yáñez, Manuel

doi:10.1039/c0cc04675b

Cited by 14 publications

(8 citation statements)

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“…More seminal works are those by Bachrach on the general issue of nucleophilic substitution to organosulfides and organoselenides. Particularly interesting are the very recent contributions by Yáñez − about the reduction of diselenides investigated with highly accurate ab initio calculations. Yáñez et al also reported results on the reactivity of disulfide and diselenide derivatives toward F – and CN – nucleophiles.…”

Section: Introductionmentioning

confidence: 99%

Addition–Elimination or Nucleophilic Substitution? Understanding the Energy Profiles for the Reaction of Chalcogenolates with Dichalcogenides

Bortoli

Wolters

Orian

et al. 2016

J. Chem. Theory Comput.

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We have quantum chemically explored the mechanism of the substitution reaction between CH3X(-) and the homo- and heterodichalcogenides CH3X'X″CH3 (X, X', X″ = S, Se, Te) using relativistic density functional theory at ZORA-OLYP/TZ2P and COSMO for simulating the effect of aqueous solvation. In the gas phase, all substitution reactions proceed via a triple-well addition-elimination mechanism that involves a stable three-center intermediate. Aqueous solvation, in some cases, switches the character of the mechanism to double-well SN2 in which the stable three-center intermediate has become a labile transition state. We rationalize reactivity trends and some puzzling aspects of these elementary reactions, in particular, vanishing activation energies and ghost three-center intermediates, using the activation strain model (ASM).

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Section: Introductionmentioning

confidence: 99%

Addition–Elimination or Nucleophilic Substitution? Understanding the Energy Profiles for the Reaction of Chalcogenolates with Dichalcogenides

Bortoli

Wolters

Orian

et al. 2016

J. Chem. Theory Comput.

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“…In order to better understand the phenomena observed experimentally, many theoretical studies have been carried out, modeling organoselenium antioxidants − and thio- and selenouracils , by density functional methods. Recently Gámez et al − have published a series of studies on electron capture and bond cleavage in disulfides and diselenides using high-level conventional electronic structure methods.…”

Section: Introductionmentioning

confidence: 99%

Systematic Study of the Performance of Density Functional Theory Methods for Prediction of Energies and Geometries of Organoselenium Compounds

Heverly‐Coulson

Boyd

2011

J. Phys. Chem. A

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A variety of density functional theory (DFT) methods are paired with Pople basis sets of varying sizes and evaluated for use with organoselenium compounds. The ability of each method to predict reliable geometries and energies is determined through comparison with quadratic configuration interaction with single and double excitations (QCISD) results. The recommended procedure for accurate prediction of energies and geometries is to use the B3PW91 functional with the 6-311G(2df,p) basis set. The B3PW91/6-31G(d,p) level of theory gives almost identical geometries as larger basis sets, so geometries can be predicted at this level for computational efficiency.

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“…Having two electrons in the highest bonding sigma orbital and one electron in the lowest antibonding sigma orbital results in the formation of a half bond (bond order = 0.5) and hence these 2c‐3e bond is also known as hemi bond or half bond. The typical symbol for such anionic systems is (RX.˙.XR) •‐ in which X denotes S, Se, N, P, and so on and R denotes Ph, CH 3 , and other functional groups . Electron capture dissociation (ECD) with Fourier transform ion cyclotron mass spectrometry (FTICR MS) has been used for direct measurement of sulfur and selenium centered 2c‐3e bond complexes …”

Section: Introductionmentioning

confidence: 99%

Effect of excess electron on structure, bonding, and spectral properties of sulfur/selenium based dichalcogen systems

Kumar

Maity

2018

Int J of Quantum Chemistry

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First principle based quantum chemical methods are employed to characterize structure, bonding, and spectral properties of sulfur and selenium based dichalcogen systems in presence of an excess electron. Inter molecular two-center three-electron (2c-3e) bonding between two chalcogen (X) atoms is described in the systems of the type (R-X) 2•-(R = Ph, PhCH 2 X = S, Se). In addition, effect of electron withdrawing (-NO 2 ) and electron donating (-CH 3 ) groups in phenyl ring on the stability of these 2c-3e bonded systems is also studied in water medium applying a macroscopic hydration model. Molecular parameters and binding energy of the neutral, (R-X) 2 and reduced, (R-X) 2 •dichalcogen systems are compared. Search for minimum energy structures of these open shell doublet systems are carried out applying various density functionals with dispersion corrections and MP2 method considering 6-311++G (d,p) set of basis functions for all atoms. Effect of water medium is introduced through a macroscopic solvation model based on density (SMD). Frontier molecular orbitals based analysis is carried out for showing the definite presence of 2c-3e bond between two chalcogen atoms in these radical anions of sulfur and selenium based aromatic dichalcogen systems. Excited state calculations are performed on all these systems using Time Dependent Density Functional Theory (TDDFT). UV-Vis spectra are simulated and effect of solvent water on the absorption maximum of these radical anions is discussed. This study illustrates that the combination of electronic effect and geometrical flexibility decides the strength of two-center three-electron bond in these systems. K E Y W O R D S 2c-3e bond, antioxidant, chalcogen, density functional theory, excess electron, hemi bond, radical anion, selenium, sulfur 1 | INTRODUCTIONSulfur and selenium are present in amino acids, peptides, and proteins, essential for various biological redox reactions. Selenocystine and selenomethonine systems can act as an antioxidant by killing harmful peroxides in organisms, and these are also responsible for protection against inflammation and cancer. [1][2][3] Sulfur and selenium based diaryl dichalcogenes are eco-friendly oxidizing agents and demanding drugs in pharmaceutical chemistry mainly for their antioxidant properties. [4] One electron reduction of neutral disulfides and diselenides may lead to the formation of two-center three-electron (2c-3e) bonded radical anion systems. [5][6][7][8][9][10][11][12][13] The extra electron in such systems is accommodated in the lowest unoccupied molecular orbital which is often an antibonding sigma orbital. Due to the presence of this electron in a repulsive antibonding orbital, such three electron bonded species are not very stable and may dissociate easily. Having two electrons in the highest bonding sigma orbital and one electron in the lowest antibonding sigma orbital results in the formation of a half bond (bond order = 0.5) and hence these 2c-3e bond is also known as hemi bond or half bond. The typical symbol for s...

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Is Se–Se bond cleavage the most favourable process in electron attachment to diselenides? The importance of asymmetry

Abstract: Accurate ab initio calculations reveal that, in contrast with what has been commonly assumed up to now, electron attachment to diselenides does not always result in a Se-Se bond fission and, in general, the mechanism behind the bond fission may involve the crossing of several states.

Cited by 14 publications

References 31 publications

Addition–Elimination or Nucleophilic Substitution? Understanding the Energy Profiles for the Reaction of Chalcogenolates with Dichalcogenides

Addition–Elimination or Nucleophilic Substitution? Understanding the Energy Profiles for the Reaction of Chalcogenolates with Dichalcogenides

Systematic Study of the Performance of Density Functional Theory Methods for Prediction of Energies and Geometries of Organoselenium Compounds

Effect of excess electron on structure, bonding, and spectral properties of sulfur/selenium based dichalcogen systems

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