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One-pot cocrystallization of two pairs of cobalt(II) complexes based on flexible triclopyr and bipyridyl coligands: structural analyses, conformation comparison, non-covalent interactions and magnetic properties
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  • Junxia Li,
  • Yi-Jing Lu,
  • Keying Quan,
  • Lingbing Wu,
  • Xun Feng,
  • weizhou Wang
Junxia Li
Luoyang Normal University

Corresponding Author:[email protected]

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Yi-Jing Lu
Luoyang Normal University
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Keying Quan
Luoyang Normal University
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Lingbing Wu
Luoyang Normal University
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Xun Feng
Luoyang Normal University
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weizhou Wang
Luoyang Normal University
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Abstract

Two pairs of cobalt(II) complexes with formulas of [Co(3,5,6-tcpa)(2,2’-bipy)Cl] (1A), [Co(3,5,6-tcpa)2(2,2’-bipy)]n (1B), [Co(3,5,6-tcpa)2(4,4’-bipy)(EtOH)]n (2A) and [Co(3,5,6-tcpa)2(4,4’-bipy)(EtOH)2]n (2B) have been cocrystallized by the solvothermal reaction of cobalt chloride hexahydrate with triclopyr (2-((3,5,6-trichloropyridin-2-yl) oxy)acetic acid, 3,5,6-Htcpa) and 2,2’-bipyridine (2,2’-bipy) or 4,4’-bipyridine (4,4’-bipy) coligands. Single-crystal X-ray diffraction analysis indicated that both 1A and 1B crystallized in triclinic system, space group P (no. 2). Compound 1A is mononuclear and 3,5,6-tcpa anion in it is a bidentate chelate ligand, while 1B is a 1D double-stranded chain structure in which 3,5,6-tcpa are bidentate bridging-μ2 linkers. In contrast, 2A has orthorhombic system, space group Aea 2(no. 41) and 2B showed monoclinic system, space group I2/a (no. 15). Complex 2A displays a 1D linear chain but 2B presents a zigzag chain, and 3,5,6-tcpa are both unidentate in them. The non-covalent interactions of Cl•••Cl/O halogen bonds, H•••O/Cl hydrogen bonds and/or π•••π stacking interactions play an important part in their crystal packing, which have been confirmed by the careful Hirshfeld surface analyses. It was proposed that flexible conformation alteration of 3,5,6-tcpa might be in charge of the cocrystallization phenomenon for 1A, 1B and 2A, 2B. The magnetic characterizations suggested antiferromagnetic coupling between neighbouring cobalt(II) centers both for 1B and 2B.