A Ferromagnetically Coupled, Bell-Shaped [Ni₄Gd₅] Cage

Reaction between NiCl₂·6H₂O, 2-hydroxy-4-methyl-6-phenyl-pyridine-3-amidoxime (H₂L), benzoic acid, and M­(NO₃)₃·6H₂O (M = Gd, Y) in MeCN under basic conditions yields the complexes [Ni^II₄Gd^III₅(PhCOO)₁₀(HL)₄(HL_zw)₄(OH)₂(NO₃)₂]­Cl·13.6MeCN·H₂O (1·13.6MeCN·H₂O) and [Ni^II₄Y^III₅(PhCOO)₁₀(HL)₄(HL_zw)₄(OH)₂(NO₃)_1.5(H₂O)_0.5]­0.5Cl­(NO₃)·3H₂O (2·3H₂O). Both clusters display similar structures, consisting of a bell-shaped {Ni^II₄M^III₅} unit, in which a linear “zigzag” {Ni₄} subunit bisects the central {M^III₅} “ring”. Direct (dc) and alternating current (ac) magnetic susceptibility measurements carried out in the 2–300 K temperature range for complexes 1 and 2 revealed ferromagnetic intermolecular interactions, while heat-capacity measurements for the Gd analogue suggest that complex 1 lowers its temperature from T = 9.6 K down to 2.3 K by adiabatically demagnetizing from B_i = 7 T to B_f = 0.