Raw computational data for the investigated diphenalenes with seven hexagonal rings which are shown in Scheme 2 of ACS Omega 10(2025)60955−60969 publication. It contains two sets of computational data: the optimized structures with vibrational frequencies, total energies, and Gibbs free energies (OPT folder), and NICS aromaticity index calculations (NICS directory).
The OPT-directory contains the calculations for the singlet states performed using the B3LYP functional (S folder), and for the triplet state by using two computational methods: UB3LYP (T folder) and RO-B3LYP (T-RO folder). The energetically most stable singlet or triplet structures (from the OPT folder) were used to prepare the Figs. 1 and 2 of the manuscript, and Tables S1-S3 of the supporting materials (SI). Geometries of optimized molecules in the form of the Cartesian xyz coordinates (extracted from *log files located in the OPT folder) are collected in Table S9 of SI.
Moreover, the HOMA aromaticity indices were calculated based on the optimised geometries (logs from the OPT folder) according the procedure described in the manuscript and used to prepare Scheme 5, Scheme 6, Figure 4 and Scheme S1, Scheme S2 as well as Table S5. The NICS directory contains data used to determine NICS aromaticity indices for the structures shown in Scheme 5, Scheme 6, Figure 4 and Tables S6-S8.
All calculations were performed using the above-mentioned B3LYP, UB3LYP, and RO-B3LYP methods, the D3 dispersion correction, and the cc-pVTZ basis set. All computational data were generated using the Gaussian 16 program.
Benzenoid hydrocarbons with two phenalene moieties, diphenalenes, comprising seven benzene rings, form three groups, with the seventh benzene ring fused to (i) zethrene, (ii) uthrene, or (iii) it links phenalene subunits. The DFT/cc-pVTZ calculations indicate that four molecules in the former group are more stable in the singlet state, four in the next in the triplet, whereas in the latter group, three are more stable as singlets and two as triplets. The singlet−triplet gap usually exceeds | ± 10| kcal/mol, but for two molecules of the (iii) group, it is close to 5 kcal/mol. For the rings at the phenalene junction, the HOMA and INICS aromaticity indices reveal a substantial decrease of aromaticity in the stable singlet state molecules. All molecules in the triplet state, and those in an excited singlet state, exhibit only a slight decline, if any. Unexpectedly, the HOMA averaged over all rings indicated the more stable singlet state to be less aromatic than the less stable triplet one, which contradicts the fairly common assumption that the greater aromaticity, the greater stability. The alternating partial spins pattern in the triplet state diphenalenes differs between the Kekuléan and non-Kekuléan ones at the phenalenes junction bond. It can be utilized to mnemotechnically predict whether an assembly of two phenalenes will have a singlet or triplet ground state.
(2026)
