Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1341123 | Polyhedron | 2005 | 6 Pages |
Biradicaloid character of three Kekulé aromatic compounds containing two phenalenyl moieties is discussed on the basis of the theoretical and experimental results. DFT calculation of the compounds reveals a small HOMO–LUMO gap with a large spatial overlap between them, leading to a singlet biradical character in a ground state and an excited triplet biradical state with a small ΔES–T. Singlet biradical character for 1 (see Fig. 1) is indicated by the X-ray crystallographic analysis, which shows dimeric pairs with substantially short non-bonding contacts of ∼3.1 Å. The ESR measurements for 1 and 3 give typical spectra for triplet species and the temperature dependence of the half-field signal indicates the thermal excitation to the triplet states.
Graphical abstractTheoretical and experimental considerations for the biradicaloid character of three phenalenyl-based compounds are described.Figure optionsDownload full-size imageDownload as PowerPoint slide