The Crystal Structure of 2,4,6-Triphenylpyrylium-1,1,3,3-tetracyanopropenide, [(C23H17O)+·(C7HN4)−]

The crystal structure of an organic charge transfer salt 2,4,6-triphenylpyrylium-1,1,3,3-tetracyanopropenide has been determined by means of X-ray diffraction. The crystals are monoclinic in the space group P21/a. The unit cell dimensions are: a=13.024, b=21.357, c=8.324Å, β=94.56°. The cation and the anion are nearly planar and form an “ion-pair.” The crystal is built up from infinite columns stacked by these ion-pairs along the c axis. Between two adjacent anions in the neighboring columns, a weak hydrogen bond (C–H···N 3.265 (5), H···N 2.185(4) Å) is present. The charge transfer interaction between the anion and the cation seems to have less influence on the crystal structure than the electrostatic force or the hydrogen bonding.