Effect of lanthanide contraction on a series of “sulfate-templated” transition-rare-earth metal clusters: Synthesis, structures and magnetic properties

Twelve novel transition-rare-earth metal clusters, formulated as [Ni18Pr14(μ3OH)14 (dmpa)10 (mmt)10(SO4)4(CH3COO)16]∙9CH3OH∙5H2O (1, H3dmpa = dimethylolpropionic acid, and Hmmt = 2-mercapto-5-methyl-1,3,4-thiadiazole) [Ni36RE102(OH)138 (mmt)18(Hdmpa)30(H2dmpa)12(CH3COO) 72(NO3)36(SO4)18(H2O)30]·Br6 (RE = Nd (2), Sm (3), Eu (4) and Gd (5)) [Ni12RE10(μ3-OH)10 (dmpa)8 (mmt)8(SO4)2(CH3COO)8(H2O)4]∙8CH3OH∙7H2O (RE = Tb (6), Dy (7), Ho (8), Er (9) and Y (10)) [Ni8Pr8(μ3-OH)8 (mmt)8(Hdpga)16(CH3COO)8]·8CH3OH (11, H2dpga = diphenyl-glycolic acid), and [Ni16Tb6(μ3-OH)24 (mmt)8(Hdpga)4 (dpga)4(CH3COO)2(NO3)4(H2O)2]∙12CH3OH∙5H2O (12), were synthesized solvothermally by using different ligand combinations and rare earth nitrates. X-ray crystal structure analyses reveal that complexes 1 and 12 possess sandwich-like structure. Compounds 2–5 are isostructural and feature a hexagonal structure, shaped like a "Star of David". Isostructural 6–10 present ring-like structure, as well as the cluster 11. The structural variations of these complexes can be attributed to the effect of lanthanide contraction. Moreover, the template effect of SO42− anion derived from the slow decomposition of Hmmt ligand also plays a significant role in the formation of cluster skeletons. The in-situ mechanism for the generation of sulfate anion is briefly discussed. Meanwhile, the magnetic properties of complexes 2–11 were studied which show typical antiferromagnetic interactions.