Robert L. LaDuca

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.

Control of chirality and catenation in cobalt and cadmium camphorate coordination complexes

Hydrothermal reaction of either cobalt or cadmium nitrate, D-camphoric acid (H2cam), and conformationally flexible dipyridylamide ligands produced five coordination networks which were structurally characterized by single-crystal X-ray diffraction. {[Co2(DL-cam)2(bdn)]·2H2O}n (1, bdn = N,N′-(butane-1,4-diyl)dinicotinamide) possesses {Co2(OCO)4} paddlewheel dimer-based [Co2(DL-cam)2] grid layers pillared by bdn ligands into a 6-connected 41263pcu network. In contrast, the cadmium analog {[Cd2(D-cam)2(bdn)2]·5H2O}n (2) shows {Cd2(OCO)2} dimer-based [Cd2(D-cam)2] layers tethered by bdn ligands into an 8-connected 42464bcu network. {[Co2(D-cam)2(pdn)]·2H2O}n (3, pdn = N,N′-(propane-1,3-diyl)dinicotinamide) manifests a self-penetrated 446810 mab network in contrast to 1, and retains chirality. {[Cd2(D-cam)2(pdn)]·H2O}n (4) manifests {Cd2(OCO)4} paddlewheel dimer-based [Cd2(D-cam)2] grids, connected by exotridentate pbn ligands into a unique 3,7-connected 3D network with (3·52)(324456687) topology derived from a rare non-self-penetrated 4966acs topology sublattice. {[Co2(DL-cam)2(pedn)]·2H2O}n (5, pedn = N,N′-(pentane-1,5-diyl)dinicotinamide) shows a hybrid structure of discrete slabs of 3D pcu network with interleaved 2D hxl (3,6) layers at random intervals, instead of the self-penetrated mab network seen in 3. The specific coordination environments and dipyridylamide lengths result in control of topology and self-penetration in this series of coordination networks. The cadmium complexes 2 and 4 were assayed for luminescent and nitrobenzene detection properties. Thermal properties of 1–5 are also discussed.