Are Multicentre Bond Indices and Related Quantities Reliable Predictors of Excited-State Aromaticity?

0533432 - ÚCHP 2021 RIV CH eng J - Journal Article
Ponec, Robert - Cooper, D.L. - Karadakov, P.B.
Are Multicentre Bond Indices and Related Quantities Reliable Predictors of Excited-State Aromaticity?
Molecules. Roč. 25, č. 20 (2020), č. článku 4791. E-ISSN 1420-3049
Institutional support: RVO:67985858
Keywords : excited-state aromaticity reversals * multicentre bond indices * molecular similarity
OECD category: Physical chemistry
Impact factor: 4.412, year: 2020
Method of publishing: Open access
https://www.mdpi.com/1420-3049/25/20/4791

Systematic scrutiny is carried out of the ability of multicentre bond indices and the NOEL-based similarity index dAB to serve as excited-state aromaticity criteria. These indices were calculated using state-optimized complete active-space self-consistent field wavefunctions for several low-lying singlet and triplet states of the paradigmatic molecules of benzene and square cyclobutadiene and the inorganic ring S2N2. The comparison of the excited-state indices with aromaticity trends for individual excited states suggested by the values of magnetic aromaticity criteria show that whereas the indices work well for aromaticity reversals between the ground singlet and first triplet electronic states, addressed by Baird’s rule, there are no straightforward parallels between the two sets of data for singlet excited states. The problems experienced while applying multicentre bond indices and dAB to singlet excited states are explained by the loss of the information inherently present in wavefunctions and/or pair densities when calculating the first-order density matrix.
Permanent Link: http://hdl.handle.net/11104/0311815