Incorporating Metal Clusters into Three-Dimensional Ln(III)−Cu(I) Coordination Frameworks through Linear Ligands

By using linear multifunctional ligands with different geometries, three novel three-dimensional (3D) Ln−M
heterometallic coordination polymers, [Nd(H2O)2(CuI)2(nic)3]·H2O (1) (Hnic = nicotinic acid) and [LnCu(inic)2(ox)]·H2O [Ln =
Nd (2), Eu (3); Hinic = isonicotinic acid, H2ox = oxalic acid], have been synthesized under hydrothermal conditions. Compound
1 exhibits a novel 3D coordination framework constructed by Cu4I4 clusters, Nd centers, and nic ligands. Our present work represents
the first example of 3D Ln−M heterometallic coordination framework incorporating discrete cubane transition metal clusters covalently
bonded to lanthanide centers through linear ligands. An unusual chemical rearrangement from Hinic to ox occurs in the formation
of 2 and 3. Compounds 2 and 3 are isostructural and possess the first 3D coordination framework based on the linkage of two-dimensional layers constructed by tetranuclear Ln2Cu2 clusters and inic ligands. Furthermore, the luminescent properties of 3 were
studied.