Cobalt and nickel coordination polymers containing 3-pyridylnicotinamide and five-membered ring dicarboxylates

Cobalt and nickel coordination polymers containing the conformationally flexible 3-pyridylnicotinamide (3-pna) ligand and a five-membered ring-based dicarboxylate ligand have been prepared and structurally characterized via single-crystal X-ray diffraction. [Co(tpdc)(3-pna)]n (1) was prepared using 2,5-thiophenedicarboxylic acid (H2tpdc). This material shows a 2-D layer structure containing {Co2(OCO)2} dimers linked by tpdc and 3-pna ligands. Compound 1 manifests an underlying 3,5-connected (426)(42678) 3,5L2 topology. The isostructural pair of solids [Co(D-cam)(3-pna)(H2O)2]n (2) and [Ni(D-cam)(3-pna)(H2O)2]n (3) was obtained from the chiral D-camphorate (D-cam) ligand. These two materials possess acentric ribbon coordination polymer motifs. Compound 1 manifests antiferromagnetic coupling concomitant with Kramers doublet formation. Thermal properties of these materials are also discussed.