Can Anti‐Aufbau DFT Calculations Estimate Singlet Excited State Aromaticity? Correspondence on "Dibenzoarsepins: Planarization of 8π‐Electron System in the Lowest Singlet Excited State". (8th May 2020)

• Record Type: Journal Article
• Authors: Karadakov, Peter B.; Saito, Shohei
• Is Part Of: Angewandte Chemie. Volume 132:Number 24(2020)
• Page Start: 9312
• Page End: 9314
• Publication Date: 2020-05-08
• Subjects: anti-aufbau DFT -- arsepines -- Baird's rule -- excited-state aromaticity -- NICS; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202001934
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: The simple anti‐aufbau DFT approach for estimating singlet excited state aromaticity suggested in a recent Communication published in this journal is shown to produce incorrect results because it targets a linear combination of the singlet and triplet configurations involving the HOMO and LUMO rather than the first singlet excited state. If the S1 state of a molecule is dominated by the HOMO→LUMO excitation, a comparably simple but theoretically consistent and qualitatively correct approximation to the S1 wavefunction can be achieved by performing a small "two electrons in two orbitals" CASSCF(2, 2) calculation which can be followed by the evaluation of magnetic aromaticity criteria such as NICS. Abstract : The simple anti‐aufbau DFT approach for estimating singlet excited state aromaticity suggested in a recent Communication is shown to produce incorrect results because it targets a linear combination of the singlet and triplet configurations involving the HOMO and LUMO rather than the first singlet excited state.