Proton-conducting layered structures based on transition metal oxo-clusters supported by Sb(iii) tartrate scaffolds

摘要

Two transition metal-antimony oxo-cluster based compounds, H-5{MCd(H2O)(6)[M(H2O)(3)Co(3)Sb(V)SbIII6(mu(3)-O)(8)(l-tta)(6)]}7H(2)O (1) (M = Cd-0.5 + Co-0.5) and H3K5(H2O)(11){Cd(H2O)(4)[Cd(H2O)Fe4Cd2Sb6(mu(4)-O)(5)(mu(3)-O)(3)(l-tta)(6)][Cd(H2O)(2)Fe4Cd2Sb6(mu(4)-O)(4)(mu(3)-O)(4)(l-tta)(6)][Cd(H2O)(2)Fe4Cd2Sb6(mu(4)-O)(4)(mu(3)-O)(4)(l-tta)(6)Cd(H2O)(5)]}17H(2)O (2) (L-H(4)tta = l-tartaric acid) were hydrothermally synthesized and characterized. Compound 1 features a [MCo(3)Sb(V)SbIII6(mu(3)-O)(8)(l-tta)(6)(H2O)(3)](9-) cluster, while compound 2 contains three types of clusters, namely, [Cd(H2O)Fe4Cd2Sb6(mu(4)-O)(5)(mu(3)-O)(3)(l-tta)(6)](4-), [Cd(H2O)(2)Fe4Cd2Sb6(mu(4)-O)(4)(mu(3)-O)(4)(l-tta)(6)](4-) and [Cd(H2O)(2)Fe4Cd2Sb6(mu(4)-O)(4)(mu(3)-O)(4)(l-tta)(6)Cd(H2O)(5)](2-). All the clusters are of sandwich-type with {Sb-3(mu(3)-O)(l-tta)} scaffolds on the top and bottom. The Cd (and M in 1) ions interconnect the clusters into layered structures in both compounds. To the best of our knowledge, this is the first report of transition metal-antimony oxo-clusters that simultaneously contain the first-row and second-raw transition metal ions, and compound 1 represents the first example of such type of clusters that contain Sb(v). The two compounds exhibit proton conductivity with the values of 2.43 x 10(-3) and 2.95 x 10(-3) S cm(-1) at 85 degrees C under 98% relative humidity, respectively.