title: Crystal structure of triclopyr.
abstract: In the title compound {systematic name: 2-[(3,5,6-tri-chloro-pyridin-2-yl)-oxy]acetic acid}, the herbicide triclopyr, C7H4Cl3NO3, the asymmetric unit comprises two independent mol-ecules in which the dihedral angles between the mean plane of the carb-oxy-lic acid group and the pyridyl ring plane are 79.3 (6) and 83.8 (5)°. In the crystal, pairs of inter-molecular O-H⋯O hydrogen bonds form dimers through an R 2 (2)(8) ring motif and are extended into chains along [100] by weak π-π inter-actions [ring centroid separations = 3.799 (4) and 3.810 (4) Å]. In addition, short inter-molecular 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).
authors.affiliation: Department of Chemistry and Research Institute of Natural Sciences, Gyeongsang National University, Jinju 660-701, Republic of Korea.
authors.forename: Seonghwa
authors.initials: S
authors.lastname: Cho
authors.affiliation: Department of Chemistry and Research Institute of Natural Sciences, Gyeongsang National University, Jinju 660-701, Republic of Korea.
authors.forename: Jineun
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Chemistry and Research Institute of Natural Sciences, Gyeongsang National University, Jinju 660-701, Republic of Korea.
authors.forename: Youngeun
authors.initials: Y
authors.lastname: Jeon
authors.affiliation: Department of Chemistry and Research Institute of Natural Sciences, Gyeongsang National University, Jinju 660-701, Republic of Korea.
authors.forename: Tae Ho
authors.initials: TH
authors.lastname: Kim
keywords: crystal structure; herbicide; hydrogen-bonded dimers; non-merohedral twinning; triclopyr; π–π inter­actions