Mixed stacking and stoichiometry in a π-molecular complex between fluorene and 1,3,5-trinitrobenzene

The crystal structure of the title complex, fluorene-1,3,5-trinitrobenzene (1.5/2) (1.5C 13 H 10 .2C 6 H 3 N 3 O 6 ) has been determined at room temperature. The molecule crystallizes in a triclinic cell and in the P1 space group. One of the three fluorene molecules in the unit cell is located at a special position and adopts two different orientations that are related by an inversion center. Therefore, the asymmetric unit contains 1.5 fluorene molecules and two molecules of 1,3,5-trinitrobenzene. Acceptor and donor molecules are arranged in mixed stacks, one with 1:1 and the other with 2:1 trinitrobenzene:fluorene stoichiometries. This mixed arrangement and the composition of the asymmetric unit explains the global 4:3 stoichiometry. These two independent stacking directions are parallel to the c and a axes, respectively.