Tris(thianthrene)(2+) bis­(dodeca­methyl­carba-closo-dodeca­borate) dichloro­methane tetra­solvate: a crossed triple-decker π-trimer dication

The title compound, (3C₁₂H₈S₂)²⁺·2C₁₃H₃₆B₁₁⁻·4CH₂Cl₂, contains an unusual cation–radical association comprising a π-­trimer dication of crossed thianthrenes. The thianthrene mol­ecular planes are essentially cofacial, but the S...S axes of adjacent mol­ecules are orthogonal to each other. The outer thianthrenes (both located on mirror planes bisecting the units at the S atoms) are bent slightly towards the inner and planar thianthrene (residing on a 2/m symmetry element with the S atoms on the twofold rotation axis), with close noncovalent separations of 3.1 Å indicating strong inter­planar inter­actions within the trimeric dication. Bond-length analysis indicates that the 2+ charge is delocalized over the three stacked thianthrenes with the maximum charge on the central unit. The crossed monomer arrangement is attributed to the frontier-orbital symmetry that allows various π-bonding orientations between thianthrene mol­ecules. The CB₁₁(CH₃)₁₂⁻ counter-ion resides on a mirror plane. One of the CH₂Cl₂ solvent mol­ecules resides on a twofold rotation axis, whereas the other is located on a mirror plane.