Discrete Binuclear Cobalt(III) Bis-dioximates with Wheel-and-Axle Topology as Building Blocks To Afford Porous Supramolecular Metal–Organic Frameworks

Abstract

Three binuclear and one mononuclear cobalt(III) dioximates with the compositions [Co2(dmgH)4(bpy)Cl2]·1.5dmf (1), [Co2(nioxH)4(bpy)Cl2]·0.5H2O (2), [Co2(dmgH)4(bpe)Cl2]·0.5H2O (3), and [Co(dmgH)2(bpy)Cl]·H2O (4) (where dmgH2 = dimethylglyoxime, nioxH2 = 1,2-cyclohexanedionedioxime, bpy = 4,4′-bipyridine, bpe = 1,2-bis(4-pyridyl)ethane, and dmf = N,N-dimethylformamide) were prepared by replacement of water molecule in Co(III) mononuclear dioximates by bpy and bpe ligands. All compounds were characterized by single-crystal X-ray diffraction and spectroscopic techniques. In all complexes Co(III) atoms have an identical octahedral N5Cl environment formulated by four nitrogen atoms of two mono-deprotonated oxime ligands in a square planar mode, and the nitrogen atom of the bpy/bpe molecules and chloride atom in the axial positions. In 1–3 bpy/bpe exobidentate spacer ligands serve as bridging “rods” and unite two planar cobalt(III) bis-dioximates in binuclear complex with wheel-and-axle topology. The packing of...