Isopolymolybdate-Based Cobalt/Nickel Coordination Polymers Constructed by V-Type N-Donor Ligands

Four novel isopolymolybdate-based coordination polymers (CPs), constructed from 2,6-bis(1,2,4-triazol-1-yl)pyridine (btp), 1,3-bis(4H-1,2,4-triazol-4-yl)benzene (btb), and 3,5-bis(1-imidazolium)pyridine (bip), have been synthesized under a hydrothermal method: {[Co(btp)(H2O)2(β-Mo8O26)0.5]·3H2O}n(1), [Ni(btp)(H4Mo6O22)0.5]n(2), [Co(btb)(H2O)(β-Mo8O26)0.5]n(3), and {[Co(Hbip)2(H2O)2(γ-Mo8O26)]·6H2O}n(4). Complex 1exhibits one 3D framework with an unexpected 3-nodal 2,4,6-c net topology containing the 1D {β-Mo8O26}nchains, 6-connected CoIIcenters, and V-type coordinated btp ligands. The neighboring [Mo6O22]4–anions of complex 2are bridged by the NiIIcenters to build one 2D {Ni2(Mo6O22)} network, which is arranged into the 3D framework through the weak π···π stacking interactions. In compound 3, one 3D framework is formed by the adjacent 1D {Co2(btp)2}nchains connected by {β-Mo8O26}nunits, which demonstrates a rare 4,6-c fsc topology. In complex 4, one 2D {Co(Hbip)2(γ-Mo8O26)} layer with a (4, 4) network is connected to one 3D hydrogen-bonding framework viaN-H···O and O-H···O hydrogen bonds. Magnetic data indicate that complexes 1and 4exhibit antiferromagnetic behaviors, whereas complexes 2and 3reveal spin-canting magnetic behavior and metamagnetic behavior, respectively. In addition, the proton conductivity of complexes 3and 4was investigated, showing that compound 4has good proton conductivity at 85 °C and a relative humidity of 98% RH.