A Heniconuclear {Mn₂₁} Cluster-Based Coordination Polymer with Manganese(II) Linkers Showing High Proton Conductivity

An unprecedented metal-linked cluster-based coordination polymer, composed of heniconuclear {Mn₂₁} clusters and Mn­(II) ions as the nodes and linkers, respectively, was self-assembled from a facile aqueous synthesis. The structural analysis reveals that the compound possesses a rare 3D 8-connected hex framework topology. Significantly, the compound demonstrates a high proton conductivity of 1.06 mS cm^–1 at 373 K and 98% RH and exhibits a magnetocaloric effect with a magnetic entropy change of −9.94 J kg^–1 K^–1 at H = 80 kOe and T = 6.0 K.