A pair of cobalt(II) complexes with formulas of [Co(3,5,6-tcpa)(2,2 '-bpy)Cl] (1A) and [Co(3,5,6-tcpa)2(2,2 '- bpy)]n (1B) have been cocrystallized by the solvothermal reaction of cobalt chloride hexahydrate with triclopyr (systematic name 2-((3,5,6-trichloropyridin-2-yl) oxy)acetic acid, abbreviation 3,5,6-Htcpa) and 2,2 '-bipyridine (2,2 '-bpy). Single-crystal X-ray diffraction analysis indicated that both 1A and 1B crystallized in triclinic system, space group P1 (no. 2). Compound 1A is mononuclear and 3,5,6-tcpa anion in it is a bidentate chelate ligand. In contrast, 1B is a 1D double-stranded chain structure in which 3,5,6-tcpa are bidentate bridging-mu 2 linkers. The non-covalent interactions of Cl center dot center dot center dot Cl halogen bonds, C-H center dot center dot center dot O/Cl hydrogen bonds as well as 7L center dot center dot center dot 7L stacking interactions play an important part in their crystal packing, which have been confirmed by the careful Hirshfeld surface analyses. After deeply structural analyses, it was proposed that flexible conformation alteration of 3,5,6-tcpa might be in charge of the cocrystallization phenomenon of 1A and 1B. In addition, the magnetic characterizations suggested antiferromagnetic coupling between neighbouring cobalt(II) centers in 1B.

Abstract A new copper(II) complex [Cu(3,5,6-tcpa)(2,2′-bipy)Cl] (1) has been obtained through the one-pot hydrothermal reaction of copper chloride dihydrate with triclopyr (systematic name 2-((3,5,6-trichloropyridin-2-yl)oxy)acetic acid, abbreviation 3,5,6-Htcpa) and 2,2′-bipyridine (2,2′-bipy) coligands. 1 has crystallized in triclinic crystal system, P 1 ‾ $\overline{1}$ space group. The central copper(II) ion displayed a distorted square–pyramidal geometry and was connected by one chlorido co-ligand (Clˉ), one 3,5,6-tcpa anionic chelator and one chelating 2,2’-bipy ligand to afford a mononuclear structure. 1 is further extended into a 3D network by the non-covalent interactions of H⋯Cl, H⋯O hydrogen bonds, aromatic π⋯π stacking together with Cl⋯Cl halogen bond interactions. The co-crystallization process, the crystal structure of 1 as well as the Hirshfeld surface analysis for 1 have been analyzed and described. In addition, the flexible conformation of phenoxy methylene group among 1, triclopyr acid and its previously reported co-crystallized compound also have been carefully compared and discussed.