Tricomponent azide, tetrazolate, and carboxylate cobridging magnetic systems: Ferromagnetic coupling, metamagnetism, and single-chain magnetism

Three novel coordination polymers with azide and a bifunctional zwitterionic ligand bearing carboxylate and tetrazolate as bridging groups, [M(L)(N₃)]·xH₂O [L=1-(carboxylatomethyl)-4-(5- tetrazolato)pyridinium, M=Cu (1, x=2), Ni (2, x=1), and Co (3, x=1)], have been synthesized and characterized by X-ray crystallography and magnetic measurements. The compounds consist of two-dimensional coordination layers in which uniform anionic chains with the unprecedented tricomponent (μ-azide)(μ-tetrazolate)(μ-carboxylate) bridges are cross-linked by cationic 1-methylenepyridinium spacers. The tricomponent bridges induce ferromagnetic interactions in all the compounds. Furthermore, this isostructural series of ferromagnetic-chain-based compounds has allowed us to observe distinct bulk properties that are dependent upon the natures of the different spin carriers: with the isotropic Cu^II ion, 1 exhibits a paramagnetic phase of the ferromagnetic chains without long-range magnetic order above 2 K; with the weakly anisotropic Ni^II ions, 2 displays antiferromagnetic ordering and field-induced metamagnetism without slow dynamic relaxation; and with Co^II, which has strong magnetic anisotropy due to first-order spin-orbital coupling, 3 exhibits magnetic hysteresis and slow magnetization dynamics typical of single-chain magnets.