The crystal and molecular structure of the nematogenic compound N-p-methoxybenzylidene-p-phenylazoaniline (MBPAA)

Abstract

The crystalline form of N-p-methoxybenzylidine-p-phenylazoaniline (MBPAA) has a monoclinic unit cell,13; space group P2';c, with eight molecules per cell. The cell parameters are a = 9.77 (1), b = 23.65 (2), c =13; 15.64 (1) A and fJ= 112.4 (3)0. The crystal structure was solved by a combination of direct methods, packing13; considerations and trial calculations, and has been refined by block-diagonal least-squares calculations to13; R = 0.126 for 1071 photographically measured reflexions. One of the crystallographic ally independent13; molecules in the asymmetric part has been found to have partial positional disorder due to the existence of13; two rotational conformers of that part of the molecule, occurring with unequal weights. In the crystal structure13; neighbouring molecules are oriented antiparallel to each other and the molecular arrangement corresponds13; to a herringbone-like pattern.