Diverse Structures and Ferro-/Ferri-/Antiferromagnetic Interactions of Pyridyltetrazole Coordination Polymers with Polycarboxylate Auxiliary Ligands

Metal salts and 3/4-pyridyltetrazoles (3/4-Hptz) react with oxalic acid (H(2)ox), 1,2,4,5-benzenetetracarboxylic acid (H(4)btec), isophthalic acid (H(2)ip), and 1,2,3,4-butanetetracarboxylic add (H(4)btca) to afford six coordination polymers, namely, [Cu(4-ptz)(ox)(0.5)] (1), [Cu(4-Hptz)-(btec)(0.5)](n) (2), [Co-2(3-ptz)(ip)(OH)(H2O)](n), (3), {[Co-1.5(3-ptz)-(btca)(0.5)(H2O)]center dot H2O}(n) (4), {[Co-3(4-ptz)(2)(btca)(H2O)(3)]center dot 2H(2)O} (5), and {[Cd-2(4-ptz)(2)(btca)(0.5)(H2O)(3)]center dot DME center dot 4H(2)O} (6). Their structures were characterized by EA, IR, PXRD, TGA, and single-crystal XRD. 3/4 Pyridyltetrazoles display mu(2), mu(3)-, and mu(5)-coordination modes in them. Complex 1 is a 3D MOF constructed from a 2D (4,4) [Cu(4-ptz)](n) grid pillared by an oxalate spacer. Complex 2 displays a 2D network containing a square planar Cul and elongated octahedral Cu2 centers. Complex 3 shows a 2D network containing mu(5)-ptz, mu(3)-ip, and mu(3)-OH. Complex 4 exhibits a 3D MOF assembled by a 2D [Co-1.5(btca)(0.5)](n) network pillared by a 3-ptz spacer. Complex 5 displays a 3D porous MOF with nanosized rectangular tunnels. Complex 6 features a 3D porous MOF built by 2D [Cd-2(4-ptz)(btca)(0.5)](n) network pillared by a 4-ptz spacer. Variable-temperature magnetic susceptibility and magneto-structural correlation studies indicate that five Cu-II/Co-II complexes present remarkable magnetic coupling diversity from ferro-, to ferri-, to antiferromagnetic interactions. Complex 1 shows strong antiferromagnetic behavior originating from the oxalate-bridging Cull dimer (J(ox) = 94.7 cm(-1)) and the tetrazole-bridging Cull dimer (J(ptz) =-61.0 cm(-1)). Complex 2 presents a weak ferromagnetic interaction (J = 0.82 cm(-1)) originating from the magnetic orbital orthogonality between square planar Cu-II and octahedral Cu-II centers. Complex 3 displays ferrimagnetic coupling in the Co-3(mu(3)-OH) triangle. Two btca Co-II complexes show antiferromagnetic interactions originating from carboxyl-bridging trinuclear Co-II clusters with the theta values of-17.08 K for 4 and 8.6 K for S. The thermal behaviors of these nitrogen-rich tetrazole complexes are investigated. Anhydrous complexes 1-3 containing rigid polycarboxylates are thermally stable to 250-300 C and then decompose explosively, whereas complexes 4-6 with flexible butanetetracarboxylate decompose smoothly.