Propeller-like conformation of diphenylacetic acid

摘要

Crystal structure of diphenylacetic acid has been solved by X-ray diffraction. The crystals are monoclinic, space group P2(1)/c, with a = 12.254(4) angstrom, b = 7.2260(8) angstrom, c = 17.521(4) angstrom, beta = 133.38(1)degrees, Mr = 212.24, V = 1127.6(5) angstrom(3), Z = 4 and R = 0.045. A strong hydrogen bond links the molecules in dimers. The dimers are connected by weaker C-H center dot center dot center dot pi and pi center dot center dot center dot pi 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.