The synthesis, structure and magnetism of tetranuclear complexes, [Ln4(LH2)2(η1–Piv)(η2–Piv)(μ3−O2)2(H2O)2]·2MeOH (1, Ln = GdIII; 2,Ln = DyIII; 3, Ln = TbIII; 4, Ln = ErIII) (LH4 = 6-((bis(2-hydroxyethyl)amino)-N´-(2-hydroxybenzylidene)picolinohydrazide), (piv = pivalate...