A method to obtain an organic mixed‐valence state with long‐range delocalization is proposed, which enables the selective generation of half‐filled (n/2‐charged) polycations from linearly bridged oligomers with n electron‐donating units. When π‐extended phenylenediamine units are connected by meta‐xylylene‐type spacers, the resulting oligomers adopt non‐folded structures in the neutral state owing to the non‐conjugating and flexible nature of the spacer, whereas the structure shows a drastic change into a one‐dimensional columnar stack upon oxidation to the corresponding half‐filled polycations. Although they are nano‐sized discrete molecules, they can mimic the electronic structure of crystalline organic conductors in a mixed‐valence state. The key for the oligomer design is adoption of the best‐matched spacer that facilitates formation of the singly charged pimer in the dichromophoric system whereas the corresponding doubly charged π‐dimer is disfavored. [ABSTRACT FROM AUTHOR]