Syntheses,Structures And Properties Of 3d-4f Heterometallic Dinuclesr Complexes

The 4f rare earth ions have a large high-spin ground state and great anisotropy. It can construct chiral 3d-4f metal SMMs complexes with charming properities by incorporating the 4f and 3d metal ions with chiral source. However, the 3d-4f metal complexes with chirality property are reported rarely. The properties and synthesis condition also have to be explored. In this thesis, the chiral cyclohexanediamine has been used as the chiral resource. The chiral salen-type Schiff base ligand, N,N′-(1,2-cyclohexanediylethylene)bis(5-Bromo-3-methoxy salicylic aldehyde) was obtained by Mannich condensation of the chiral cyclohexanediamine with 5-Brom-3-methoxy salicylic aldehyde. The salen-type ligands show flexible coordination modes, can supply N2O2 and O2O2 cavities to form 3d-4f heteronuclear complexes at the same time. Based on the above considerations, the synthesis, structures and magnetic properties of Cu-Ln and Ni-Ln heterometallic dinuclear complexes based on salen types ligands have been studied in this paper.By using the salen-type chiral mononuclear CuⅡL complexes as precursor buliding blocks, ten achirality Cu-Ln heterometallic dinuclear complexes, [Cu(L)Ln(NO3)3](Ln = Ce-Yb, 1-10), and six pairs of chiral Cu-Ln heterometallic dinuclear complexes, [Cu(CH3CN)(L)Ln(NO3)3](Ln = Gd(11R, 11S), Tb(12R, 12S), Dy(13R, 13S), Ho(14R, 14S), Er(15R, 15S), Yb(16R, 16S)) were obtained successfully. The single-crystal X-ray diffraction analysis revealed that the complexes 1-10 are isostructural, crystallize in space group P21/n. The complexes 11-16 are isostructural, crystallize in space group P21. Magnetic investigations showed that ferromagnetic couplings between the CuⅡ and LnⅢ ions exist in 11 R and 12 R, antiferromagnetic interaction in 14 R and 15 R, the strong spin-orbit coupling of the DyⅢ ion in 13 R. The alternating current magnetic susceptibilities showed that 12R-14 R exhibit field-induced relaxation of magnetization behavior.By using salen-type chiral mononuclear NiⅡL complexes as precursor buliding blocks, ten achirality Ni-Ln heteronuclear metal complexes, [Ni(L)Ln(NO3)3](Ln = Ce-Yb, 17-26) were synthesized successfully. The single-crystal X-ray diffraction analysis indicated that the complexes 17-26 are isostructural, and crystallize in space group P21/c. Magnetic measurements showed that ferromagnetic couplings between the NiⅡ and LnⅢ ions exist in the complexes 21 and 22, and antiferromagnetic interaction in 23. The alternating current magnetic susceptibilities showed that 22 and 23 exhibit typical features of field-induced single-molecule magnets. The external 2000 Oe dc field prohibits the quantum tunneling effect under the low-temperature effectively.