Structures and Spectroscopic Properties of Polysulfide Radical Anions: A Theoretical Perspective.
Molecules
; 28(15)2023 Jul 26.
Article
em En
| MEDLINE
| ID: mdl-37570624
ABSTRACT
The potential involvement of polysulfide radical anions Snâ¢- is a recurring theme in discussions of the basic and applied chemistry of elemental sulfur. However, while the spectroscopic features for n = 2 and 3 are well-established, information on the structures and optical characteristics of the larger congeners (n = 4-8) is sparse. To aid identification of these ephemeral species we have performed PCM-corrected DFT calculations to establish the preferred geometries for Snâ¢- (n = 4-8) in the polar media in which they are typically generated. TD-DFT calculations were then used to determine the number, nature and energies of the electronic excitations possible for these species. Numerical reliability of the approach was tested by comparison of the predicted and experimental excitation energies found for S2â¢- and S3â¢-. The low-energy (near-IR) transitions found for the two acyclic isomers of S4â¢- (C2h and C2v symmetry) and for S5â¢- (Cs symmetry) can be understood by extension of the simple HMO π-only chain model that serves for S2â¢- and S3â¢-. By contrast, the excitations predicted for the quasi-cyclic structures Snâ¢- (n = 6-8) are better described in terms of σ â σ* processes within a localized 2c-3e manifold.
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Base de dados:
MEDLINE
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2023
Tipo de documento:
Article