Design,Synthesis And Magnetic Properties Of Multidentate Nitronyl Nitroxide Radical-Metal Complexes

Two nitronyl nitroxide radicals,NITPh IM（2-[4-（1-imidazole）phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide）and NITPh-3,5-（OMe）₂（2-[4-（3,5-dimethoxy）phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide）have been synthesized and characterized.Ten novel heterospin 2p-3d-4f,2p-3d and 2p-4f complexes have been successfully synthesized based on these nitronyl nitroxides.The structures of these complexes were characterized and their magnetic properties were studied.1.The functional nitronyl nitroxide radical NITPh IM was used as a ligand to react with the mixtures of Cu（hfac）₂·2H₂O and Ln（hfac）₃·2H₂O[Ln=Gd,Tb,Dy,Er,Lu],respectively.Five new heterospin 2p–3d–4f complexes,[Ln（hfac）₃{Cu（hfac）₂}₂（NITPh IM）₂][Ln=Gd（1）,Tb（2）,Dy（3）,Er（4）,Lu（5）]have been synthesized.They are all composed of independent molecules,and the molecule exhibits a center-symmetric double-blades structure.Complexes Tb（2）and Dy（3）display frequency-dependent out-of-phase signals,indicating slow magnetic relaxation SMM behaviors.2.The 2p–3d complexes have been tried to assemble with the NITPh IM radical,meanwhile the tetrafluoroterephthalate（tftpa）as a coligand.Three new complexes,[M（NITPh IM）₄（H₂O）₂]·（Cl O₄）₂·2H₂O[M=Mn（6）,Co（7）],and[Zn（NITPh IM）₂（tftpa）]·CH₃OH（8）have been prepared.Unexpectedly,tftpa does not participate in the formation of complexes 6 and 7.Complexes 6 and 7 are isostructural,and are composed of mononuclear molecules.Each molecule contains a central M（II）ion and four coordinated NITPh IM radicals.Complex 8 is a 1D chain coordination polymer,in which the Zn（NITPh IM）₂units are bridged by tftpa dianion.The magnetic studies show that there exist weak antiferromagnetic interactions in these complexes.3.With the nitroxide radical NITPh-3,5-（OMe）₂,two new complexes have been synthesized with the formulas{Gd（hfac）₃[NITPh-3,5-（OMe）₂]₂}（9）and[Mn（hfac）₂NITPh-3,5-（OMe）₂]_n（10）,respectively.Complex 9 is composed of mononuclear molecules.The smallest asymmetric unit of 9 contains two independent molecules,of which their structural parameters are slightly different.Complex 10 consists of infinite 1D chains of[Mn（hfac）₂（NITPh-3,5-（OMe）₂）]_n,in which NITPh-3,5-（OMe）₂binds two Mn（II）ions in bis-monodentate mode.Magnetic research results indicate that the central metal Gd（III）ion of complex 9 is a ferromagnetic interaction with the free radical,and the two free radical NO groups connected by rare earth ion are antiferromagnetic coupling;The temperature-dependent magnetic susceptibility curve of complex 10 shows that there may be ferromagnetic interaction in the system.The value of the magnetic susceptibility is high which indicating that there may be magnetic order in the complex system,and further magnetic testing is still in progress.In this paper,two nitronyl nitroxide radicals have been synthesized,and ten novel NITR-metal complexes have been assembled with these radicals.The research achievements not only enrich the structural diversity of 2p-3d-4f complexes,but also provide scientific experiment basics for new functional magnetic complexes.