X-ray analyses of 2a 2+ (BF 4 -) 2 and 1a + BF 4 -using a single crystal obtained by recrystallization from CH 2 Cl 2 /Et 2 O revealed that there are the shortest intermolecular C•••C contacts of 3.3799(19) Å for 1a + BF 4 -and 3.189(5) Å for 2a 2+ (BF 4 -) 2 , respectively, both of which are smaller than the sum of the vdW radii of carbon atoms (3.4 Å) (Figure ). The value for 2a 2+ is smaller than that for 1a + . Therefore, obvious intramolecular interactions due to - stacking between cation units were expected for the cyclophane-type dications. Another feature of the packing structure is that, in cyclophane-type dication salt 2a 2+ (BF 4 -) 2 , two chromophores in the crystal are facing each other and stacked in a parallel manner, unlike that of monocation salt 1a + BF 4 -(Figure ). Compared to the dihedral angle  [11.15(6)°] between the triarylmethyl moieties for 1a + BF 4 -, the smaller value [7.71( )°] was observed for 2a 2+ (BF 4 -) 2 , i.e., cation units are almost overlapped in parallel thanks to the cyclophane structure. These results show that the molecular design of the introduction of the highly planar -system is effective for stacking of the cationic units.