Crystal structure of triclopyr

Abstract

In the title compound {systematic name: 2-[(3,5,6-trichloropyridin-2-yl)oxy]acetic acid}, the herbicide triclopyr, C7H4Cl3NO3, the asymmetric unit comprises two independent molecules in which the dihedral angles between the mean plane of the carboxylic acid group and the pyridyl ring plane are 79.3 (6) and 83.8 (5)°. In the crystal, pairs of intermolecular O—H...O hydrogen bonds form dimers through anR22(8) ring motif and are extended into chains along [100] by weak π–π interactions [ring centroid separations = 3.799 (4) and 3.810 (4) Å]. In addition, short intermolecular Cl...Cl contacts [3.458 (2) Å] connect the chains, yielding a two-dimensional architecture extending parallel to (020). The crystal studied was found to be non-merohedrally twinned with the minor component being 0.175 (4).