Crystal and molecular structure of 2,6‐bis(4‐fluorobenzylidene)cyclohexanone

Abstract

The title compound, C 20 H 16 F 2 O, crystallizes in triclinic system with P1 space group and the unit cell parameters are: a = 9.700(5), b = 11.834(6), c = 14.315(7) Å, α = 78.464(9), β = 74.394(8), γ = 86.186(9)º, V = 1551.0(1) Å 3 and Z = 4. The final R-factor is 4.8%. The cyclohexanone ring adopts a sofa conformation. The different ways of adjusting to steric repulsion results in significant differences between molecule A and B with respect to torsion angles. The steric repulsion between the aromatic groups and hydrogen atoms on the cyclohexanone ring causes increase of the values of bond angles at the C atoms joining the rings and rotation of the corresponding bond, at the expense of conjugation energy of the system. In addition to the van der

(2E,6E)-2,6-Bis(4-ethoxybenzylidene)cyclohexanone

“…It has crystallographic mirror symmetry and exhibits a butterfly-shaped geometry. Similar structures have been observed in the related substituted cyclohexanone analogues reported by Ompraba et al (2003) and Sun et al (2007). A dihedral angle of 5.46 (1)° is found between the mean planes of the two benzene rings.…”

“…For related structures, see: Du et al (2007); Liang et al (2007); Sun et al (2007); Zhou et al (2007). For background information, see: Guilford et al (1999); Ompraba et al (2003); Yu et al (2000).…”

2,6-Bis(3,4,5-trimethoxybenzylidene)cyclohexanone

“…The molecule adopts an all-trans configuration about the central olefinic bonds, exhibiting a butterfly-shaped geometry. Similar structures have been observed in the related substituted cyclohexanone analogues reported by Ompraba et al (2003) and Butcher et al (2006). The values of the C6-C7-C8-C9 and C2-C17-C18-C19 torsion angles [À34.6 (2) and 30.1 (2) , respectively] indicate deviation of the 3,4,5trimethoxyphenyl rings from the plane of the olefinic double bonds.…”