Azide-bridged Cu(II), Mn(II) and Co(II) coordination polymers constructed with a bifunctional ligand of 6-(1H-tetrazol-5-yl)-2,2'-bipyridine

Three new azide-bridged coordination polymers, [M(N3)(tzbp)] n (M = Cu, 1 center dot Cu; Mn, 2 center dot Mn; Co, 3 center dot Co), were successfully synthesized by the introduction of a bifunctional tetrazolate/2,2'-bipyridine ligand, 6-(1H-tetrazol-5-yl)-2,2'-bipyridine (Htzbp), from the in situ [2 + 3] cycloaddition of 6-cyano-2,2'-bipyridine in the presence of an excess of sodium azide under hydrothermal conditions. Compounds 1 center dot Cu-3 center dot Co were characterized by X-ray crystallography, IR spectroscopy, thermogravimetry, and elemental analysis. With tzbp-ligands acting in the chelating coordination mode, compound 1 center dot Cu was comprised of a single endon N3(-) (EO-N-3) bridged one-dimensional (1D) zigzag structure. Both compounds 2 center dot Mn and 3 center dot Co adopt two-dimensional (2D) layered structures composed of a double EO-N-3 bridged dinuclear motif, [M-2(EO-N-3)(2)], which are interlinked by tzbp(-) ligands in the chelating/bridging mode. The layers of 2 center dot Mn and 3 center dot Co are stacked on each other in center dot center dot center dot ABAB center dot center dot center dot and center dot center dot center dot AAAA center dot center dot center dot fashions, respectively. Magnetic investigations revealed that intrachain antiferromagnetic interactions were dominant in compound 1 center dot Cu, and both 2 center dot Mn and 3 center dot Co exhibited spin-canted antiferromagnetism with critical temperatures (T-N) of 3.0 and 18.4 K, respectively. Furthermore, below TN, the field-induced magnetic transitions of spin-flop and metamagnetism were observed in 2 center dot Mn and 3 center dot Co, respectively.