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

The title compound, (3C(12)H(8)S(2))(2)+.2C(13)H(36)B(11)(-).4CH(2)Cl(2), contains an unusual cation-radical association comprising a pi-trimer dication of crossed thianthrenes. The thianthrene molecular planes are essentially cofacial, but the S center dot center dot center dot 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 A 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 pi-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.