5,12-Diaminotetracenes: The Impact of Orbital Interactions between the Acene π System and Amino Groups on Their Electronic States.

5,12-Diamino-substituted tetracenes with various N-substituents have been prepared, and their molecular structural changes upon oxidation have been evaluated in association with their electronic structures. The N-substituents influence both the electronic and molecular structures of the oxidized species of 5,12-diaminotetracenes. The tetracene moiety of 5,12-bis(N,N-dianisylamino)tetracene retained its planarity during the course of two successive one-electron oxidations, whereas 5,12-bis(N,N-dimethylamino)tetracene and 5,12-bis(N-anisyl-N-methylamino)tetracene underwent substantial structural changes into butterfly like structures through a simultaneous two-electron oxidation process. The molecular structures in the oxidized states were closely related to the nature of the highest occupied orbitals, which were characterized by the extent of mixing between the fragment orbitals for the teracene moiety and the substituted amino groups in 5,12-diaminotetracenes. As a consequence, the present work revealed that the extent of folding deformation of the acene moiety in the oxidized diaminoacenes could be fine-tuned by varying the N-substituents.