[ErCu4(butyrat)4}2]·Cl3·MeOH·26H2O (1) and [YbCu4(butyrat)4}2]·Cl3·MeOH·26H2O (2) (H2butyrat = 3-aminobutyric hydroxamic acid), have been reported. X-ray crystallographic analysis reveals that the two complexes displayed nested-sandwich configurations with two 12-MC-4 metallacrown units capping LnIII in the centre. Magnetic studies revealed that 1–2 undergo antiferromagnetic coupling interaction. Magnetic measurements