Synthesis,Structure And Magnetic Properties Of New Ln(Ⅲ)-Nitronyl Nitroxide Radical Molecular Magnetic Materials

Two nitronyl nitroxide radicals,NITPhEDO（2-（3’,4’-ethylenedioxyphenyl）-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide）and NITPhNEt₂（2-（4’-diethylinphenyl）-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide）have been synthesized,and characterized with IR,elemental analyses,ESR,XRD and single-crystal X-ray diffraction.Two series of new rare earth（or transition metal）complexes have been synthesized with NITPhEDO and NITPhNEt₂as organic paramagnetic ligand,respectively.These complexes were characterized by IR,XRD and single-crystal X-ray diffraction,and the magnetic properties were studied.The first series of complexes,Ln（hfac）₃（NITPhNEt₂）₂[Ln=Sm（1）,Eu（2）,Gd（3）,Tb（4）,Dy（5）],possess similar structures.All of them are composed of mononuclear molecules.The asymmetric unit contain two independent molecules,of which their structural parameters are slightly different.Magnetic studies indicate that there are weak antiferromagnetic interactions between Ln^IIIII and NITPhNEt₂ radical for complexes 1,2,4,5.For complex 3,the intramolecular ferromagnetic interaction is found between Gd^III and NITPhNEt₂,while antiferromagnetic superexchange interaction between two NITPhNEt₂ radicals.The out-of-phase signals of AC magnetic susceptibility are visible and frequency-dependent for complexes 4 and 5,indicating the SMM magnetic behavior.The complex Cu（hfac）₂（NITPhNEt₂）（16）possess mononuclear structure,and the strong antiferromagnetic interaction are estimated between Cu^II and nitronyl nitroxide radical.The second series of complexes,Ln（hfac）₃（NITPhEDO）₂[Ln=Sm（6）,Eu（7）,Gd（8）,Tb（9）,Dy（10）,Ho（11）,Er（12）,Tm（13）,Yb（14）,Lu（15）],are isomorphous.All of them possess mononuclear structure,and the asymmetric unit contain an independent molecule.The magnetic studies indicate that there are weak antiferromagnetic interactions between Ln^IIIII and NITPhEDO for 7 and 9-15.For 8,ferromagnetic interaction between Gd^III and NITPhEDO,and antiferromagnetic superexchange interaction between two NITPhEDO have been found.The AC susceptibility of complexes 10 and 11 demonstrate that they exhibit magnetic behavior of SMMs.Some achievements have been made in the synthesis and magnetic property of Ln（III）-nitronyl nitroxide radical complexes.The results demonstrate that NITPhEDO and NI-TPhNEt₂ are excellent components for the constructing of single-molecule magnets.