A resonating broken-symmetry CI study of cationic states of phenalenyl dimeric compounds

We investigated several phenalenyl cationic dimer systems using ab initio methods. First, we examine the through-space cation dimer. The B3LYP method fails to describe the correct dissociation as in the case of usual cation dimers. On the other hand, the resonating broken symmetry configuration interaction (Res-BS CI) method based on unrestricted Hartree–Fock solutions yields the correct potential surface and correct charge distributions. Furthermore, we investigated though-bond interactions of the phenalenyl cationic dimer via acetylene and ethylene bridges. The results are considerably different from those of the though-space case, implying that these bridging units play important roles to determine charge and spin distributions. Judging from these results, different bridges-or-stacks lead to different hole behaviors, indicating the possibility of various electronic functionalities of hole-doped phenalenyl compounds. In particular, the acetylene bridge is expected to enhance the conductivity of the hole-doped phenalenyl compounds.

Graphical abstractWe investigated phenalenyl cation dimers by several ab initio methods. As in the case of simple diatomic cation dimers, the resonating configuration interaction (Res-CI) method correctly yields both the potential surface and the charge distribution of the through-space phenalenyl cation dimer, while the B3LYP and UHF methods fail to describe the potential surface and the charge distribution, respectively. On the other hands, the UHF solution reduces to the ROHF solution for the acethylene-bridged phenalynyl dimer, implying that this bridge plays a role to enhance the conductivity between phenalenyl units. In contrast, the ethylene-bridge leads to a slightly complicated Res-CI solutions based on spin-density wave types of UHF solutions.Figure optionsDownload full-size imageDownload as PowerPoint slide