A Spiropentasiladiene Radical Cation: Spin and Positive Charge Delocalization across Two Perpendicular SiâSi Bonds and UV-vis-NIR Absorption in the IR-B Region.
J Am Chem Soc
; 143(7): 2649-2653, 2021 Feb 24.
Article
em En
| MEDLINE
| ID: mdl-33565866
ABSTRACT
Spiroconjugation, that is, through-space orbital interactions between two perpendicular π orbitals, is a key concept in the contemporary molecular design of spirocyclic π-electron systems. We synthesized spiropentasiladiene radical cation salt 1 as a dark-green solid via the one-electron oxidation of the stable spiropentasiladiene 2. Characterization of the molecular structure combined with theoretical studies indicated that the spin and positive charge are delocalized across the two perpendicular SiâSi double bonds of 1. Two π(SiâSi) orbitals are split into HOMO and SOMO with a small energy gap owing to the second-order Jahn-Teller distortion and steric repulsion between bulky alkyl groups upon one-electron oxidation. In the UV-vis-NIR spectrum, the longest-wavelength absorption band of 1 (λmax = 1972 nm) covers the IR-B region (1400-3000 nm; 0.89-0.41 eV) despite having the smallest possible spiroconjugation motif. The unprecedented absorption band in the IR region was assigned to the HOMO â SOMO transition that arises from the delocalized π-orbitals in the spirocyclic Si5 skeleton.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
J Am Chem Soc
Ano de publicação:
2021
Tipo de documento:
Article