Crystal Structure of Benzene-Solvate of Bis(benzophenone) Azine: A Color Polymorph

A crystalline complex of bis(benzophenone) azine (BBA), solvated by benzene in a BBA:benzene = 1:1 ratio, was isolated as yellow crystals, and its crystal structure was determined by single-crystal X-ray diffraction analysis at 223 K. The complex crystallizes in the triclinic crystal system in the space group P1 (#2) with the cell parameters a = 8.646(6)Å, b = 9.096(5)Å, c = 9.217(6)Å, α = 78.01(2)°, β = 64.23(2)°, γ = 67.39(2)°, Z = 1, and V = 601.9(6)Å3. Benzene is embedded in a channel running along the c-axis. The yellow color of the complex, in contrast to the colorless solvent-free crystals, is attributed to the planar geometry of the C=N-N=C moiety.