Metal-ion induced ferromagnetic polarization in mixed-spin system
Three new 3d-3d heterometallic complexes, [CuII3MII(hmb)6(OH)]ClO4·H2O (M = Zn (1), Ni (2) and Co (3)) (Hhmb = 2-hydroxy-3-methoxy-benzaldehyde), have been synthesized. Structural analysis reveals that three complexes are isostructural. Three CuII ions are in a perfect trigonal geometrical frustration and form a tetrahedral frustrated system with the introduced fourth ion ZnII/NiII/CoII. Magnetic studies indicate the antiferromagnetic coupling between metal ions in all 1, 2 and 3. Due to the geometrical frustration, spin-frustrated magnetism is also the typical feature of 1-3 and the magnetostructural correlation is far more complicated than their structures. The detailed magnetic investigation found that the ground state spin of 2 cannot be simply determined by antiferromagnetically linear arrangement of spins, because the strong antiferromagnetic coupling between CuII and NiII ions quenches the spin frustration and ferromagnetically polarizes the spins of [CuII3] unit. Contrarily, the antiferromagnetic coupling between CuII and CoII ions is not strong enough in 3, so there is no similar behaviour compared to 2.