Diversity of Azido Magnetic Chains Constructed with Flexible Ligand 2,2′-Dipyridylamine

By employing a flexible molecule, 2,2'-dipyridylamine (dpa), as a bidentate coligand, three azide-bridged one-dimensional coordination polymers, [M(dpa)(N-3)(2)](n) (M = Cu, 1 . Cu; Co, 2 . Co) and [Ni(dpa)(OAc)(0.5)(N-3)(1.5)(H2O)](n) (3. Ni), have been successfully synthesized and structurally and magnetically characterized. They show versatile one-dimensional chain structures. 1 . Cu is an EO-N-3 bridged uniform chain; 2 . Co is an alternative chain linked by two EO-N-3 and two EE-N-3 bridges. Interestingly, 3. Ni is a zigzag chain linked alternatively by one EE-N-3 and a novel 3-fold bridge, which is composed of two EO-N-3 and one acetate group. This series of azido complexes demonstrates that the flexibility of the dpa ligand plays an important role in directing the structures of the final products. Magnetic studies reveal dominant intrachain antiferromagnetic couplings in compound 1 . Cu. Compounds 2 . Co and 3 . Ni are weak ferromagnets due to the spin canting, with critical temperatures of 12.4 and 32.5 K, respectively.