Propeller-like Conformation of Diphenylacetic Acid

Abstract Crystal structure of diphenylacetic acid has been solved by X-ray diffraction. The crystals are monoclinic, space group P2₁/c, with a = 12.254(4) ?, b = 7.2260(8) ?, c = 17.521(4) ?, β = 133.38(1)°, Mr = 212.24, V = 1127.6(5) ?³, Z = 4 and R = 0.045. A strong hydrogen bond links the molecules in dimers. The dimers are connected by weaker C–H···π and π···π interactions. A calculation was performed for the isolated molecule and for the dimer within the Hartree-Fock (HF) level with a 6-311G(d) basis set. In both calculations, the minimum of the energy is achieved with the phenyl rings assuming a more symmetric arrangement around the central carboxylic plane than is experimentally observed. Graphical Abstract In diphenylacetic acid the molecules are coupled in dimers by a strong hydrogen bonds. Weaker intermolecular interactions involving the aromatic ring π systems join the dimers together. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.