Home – Home – Jornals – Journal of Structural Chemistry 2009 number 4

Based on the data of the Cambridge Structural Databank, we analyzed the conformations of 139 4-X-C₆H₄-C₆H₄-4′-Y molecules (X, Y = H, F, Cl, Br, I, CH₃, OH, COOH, NH₂, NO₂, CN) and intermolecular contacts formed by these molecules in 95 homo- and heteromolecular crystals. As would be expected, the percent of planar and almost planar molecules (the angle between the planes of the phenyl fragments (ϕ) is 0-5°) in the group was higher (37%) than in biphenyl containing any substituents in the 3,3′,4,4′,5,5′-positions (26%). The percent of almost planar molecules increased considerably when X = OH (48% among molecules having at least one OH group), while equal substituents (X = Y) did not lead to a substantial increase in the relative content of conformers with ϕ in this range. In the given group of crystal structures, the specific intermolecular contacts (hydrogen bonds, Hal…Hal and Hal…N≡C contacts, etc.) often led to the formation of infinite molecular chains or their fragments (trimers and dimers). The structures containing molecules with an NH₂ group typically formed layered (2D) and framework (3D) H associates.