Doubly mononuclear cocrystal and oxalato-bridged binuclear copper compounds containing flexible 2-((3,5,6-trichloropyridin-2-yl)oxy)acetate tectons: Synthesis, crystal analysis and magnetic properties

[Display omitted] •Two new copper compounds 1 and 2 containing flexible 3, 5, 6-Htcpa ligands have been synthesized and characterized.•1 is a doubly mononuclear cocrystal and 2 is an oxalato-bridged binuclear structure.•Magnetic measurements indicated both weak antiferromagnetic coupling behavior in 1 and 2.•2 can be obtained with 1 as one of the starting marerials associated with greatly conformational variation. Two new copper compounds, namely [Cu(3,5,6-tcpa)2(H2O)4]·[Cu(3,5,6-tcpa)2(H2O)2] (1) and [Cu2(3,5,6-tcpa)2(2,2′-bipy)2(oxa)]·2EtOH (2) (3,5,6-Htcpa = 2-((3,5,6-trichloro pyridin-2-yl)oxy)acetic acid, 2,2′-bipy = 2,2′-bipyridine, oxa = oxalate dianion), have been synthesized by solvothermal method and systematically characterized. Single-crystal X-ray diffraction analysis show that 1 is an interesting double mononuclear cocrystal and consists of two discrete and stereochemically different complexes: one octahedral, the other tetrahedral about the copper centres. While for 2, two equivalent copper ions are in square pyramidal geometry and linked by oxalate anion forming a novel binuclear cluster. The OH···O hydrogen bonds, Cl···Cl halogen bonds and/or π···π stacking interactions play an important part in construction of the 3D networks for 1 and 2. The magnetic measurements indicate that there is weak antiferromagnetic coupling between two copper ions in 1 and 2. Notably, compound 2 also can be obtained in a higher yield with 1 as one of the starting material and the driving force for this transition process have been carefully discussed.