LAUSR

Abstract The reaction of Gd(NO3)3∙6H2O and [Cu2(piv)4(pivH)2] with the polydentate Schiff base ligands o-OH-C10H6-CH=NC(R)(CH2OH)2 (R = CH3, H3L1; R = C2H5, H3L2) in MeOH afforded the enneanuclear heterometallic complexes [Cu7Gd2(L1)4(HL1)2(piv)4(H2O)(MeOH)3] (1) and [Cu7Gd2(L2)4(HL2)2(piv)4(MeOH)5] (2). Crystallographic studies revealed that both complexes are isostructural and consist of a central core {Cu7Gd2(μ3-Oalkoxo)6(μ2-Oalkoxo)4(μ2-Opivalato)2}8+. Peripheral ligation and bridging are provided by four triply and two doubly deprotonated Schiff base ligands, two μ3-pivalates, two chelate pivalates, and terminal aqua and/or MeOH molecules. Magnetic susceptibility measurements revealed the presence of dominant ferromagnetic intramolecular interactions in both complexes. The magnetocaloric effect of 1 and 2 was examined via isothermal magnetization measurements under various applied fields and the maximum entropy change was found equal to 13.3 and 14.0 Jkg-1K-1 for 1 and 2, respectively, at 2 K for ΔH = 5 T.