On the structure of “tetraphenyldipyranyl ether”

The reaction product of 2,6-diphenylpyrylium perchlorate with water in presence of bases, which earlier was assigned the structure of α,α',α″,α″-tetraphenyl-γ,γ'-dipyranyl ether, is identified now as 2,6-dipyranylidene-1, 5-diphenylpentenedione-1,5 from its chemical and spectral properties and by X-ray analysis.Crystals are monoclinic, space group P2₁/n with Z =4 in a unit cell of dimensions a =24.088, b= 9.323, c = 11.289 Å, β = 95.30°. The structure was solved by direct method and refined isotropically to R = 0.126 for 2423 reflections.