Crystal structure of 5,6-didehydrodibenzo[a,e]cyclo-octene

Abstract

The structure of 5,6-didehydrobenzo[a,e]cyclo-octene C₁₆H₁₀ has been determined from single-crystal X-ray analysis by direct methods. The crystals are monoclinic, space group P2₁/c, Z= 8, a= 10.130(7), b= 12.434(2), c= 17.031 (5)Å, β= 99.05(4)°. Full-matrix least-squares refinement based on 1 517 reflexions with intensities I > 2σ(I) and 527 non-significant ones in the range 2σ(I) > I > σ(I) converged to R(R_W)= 0.053 (0.064) without and to R(R_W)= 0.086 (0.066) including non-significant reflexions. The geometry of the two independent molecules A and B is slightly different, A being planar within 0.031 Å, B within 0.174 Å. The benzene rings in B are tilted by 9.9°. The mean angular deformation of the acetylenic bonds is 26.0°.