Cl^–‑Templated Assembly of Novel Peanut-like Ln₄₀Ni₄₄ Heterometallic Clusters Exhibiting a Large Magnetocaloric Effect

Two novel and fascinating high-nuclearity lanthanide-transition (4f–3d) heterometallic clusters were obtained based on an anion-template (Cl^–) and ligand-controlled approach, formulated as [Gd₄₀­Ni₄₄­(CO₃)₁₂­(CH₃COO)₄­(IDA)₄₄­(C₂O₄)­(μ₂-O)₄­(μ₃-OH)₆₀­(μ₃-O)₆­(H₂O)₁₂]·Cl₁₀·20H₂O (abbreviated as Gd₄₀Ni₄₄, 1) and [Eu₄₀­Ni₄₄­(CO₃)₁₂­(CH₃COO)₆­(IDA)₄₄­(C₂O₄)­(μ₂-O)₄­(μ₃-OH)₆₂­(μ₃-O)₄­(H₂O)₁₂]·Cl₁₀·23H₂O (abbreviated as Eu₄₀Ni₄₄, 2), where H₂IDA = iminodiacetic acid and H₂C₂O₄ = oxalic acid. Structural analysis exhibits that the compounds 1 and 2 were both constructed by two enticing bowl-like anion units Ln₂₀Ni₂₂, featuring peanut-like structures. Besides, the assembly of Ln₂₀Ni₂₂ was templated by five Cl^– ions. Magnetically, compound 1 shows a significant magnetocaloric effect, with −ΔS_m = 36.05 J kg^–1 K^–1 at 3 K for ΔH = 7 T.