Polymorphism of mer‐μ‐oxalato‐bis[chloridotripyridinecobalt(II)] pyridine disolvate

Single crystals of a triclinic polymorphic form of mer‐μ‐oxalato‐bischloridotripyridinecobalt(II)] pyridine disolvate, Co₂(C₂O₄)Cl₂(C₅H₅N)₆]·2C₅H₅N, have been prepared by solvothermal methods. The structure and geometric parameters strongly resemble those of the previously reported monoclinic polymorph Bolte (2006). Acta Cryst. E 62 , m597–m598]. In both polymorphic forms, the dinuclear complex molecules are located on a crystallographic centre of inversion, with the Co^II cations in a distorted octahedral environment consisting of a chloride ligand, three pyridine ligands and a chelating bis‐bidentate oxalate ligand. This last serves as a bridging ligand between two Co^II cations. The polymorphs differ in the mutual orientation of their pyridine ligands in the dinuclear molecules and in their intermolecular connectivity. In the triclinic polymorph, C—H...O, C—H...Cl, C—H...π and π–π interactions link the dinuclear molecules into a three‐dimensional structure. Pyridine solvent molecules are attached to this structure via weak interactions.