| Free radical chemistry has caused great attention from researchers,not only because of unique bonds of radical compounds,but also the optical,electrical,magnetic properties and the potential applications in batteries and molecular devices.Stable organoradicals have been ubiquitously applied in metal-mediated catalysis and magnetic materials.It is of great significance for us to construct single-molecular magnets(SMM)by combining radicals with metal complexes and study the relationship between radicals and metals.Most free radicals are very reactive,resulting in short lifetimes due to oxidation,polymerization,and hydrogen abstraction.Stabilization and isolation are the most important keys to the radical chemistry.In this thesis,we summarize the development of azaacene radicals and radical ligand-containing SMM,and successfully isolated six pyrene-fused azaacene radical compounds and seven main-group element-based radical-containing lanthanide metal complexes and studied their structures and propoties.1.Azaacene radical anion salts[(18-c-6)K(THF)2]+·1·–,[(18-c-6)K(THF)2]+·2·–and azaacene diradical dianion salts[(18-c-6)K(THF)2]+[(18-c-6)K]+·12–··,[(18-c-6)K(THF)]22+·22–··are successfully isolated by reduction of the neutral pyrene-fused azaacene derivatives 1 and 2 with different equivalents of potassium graphite in THF in the presence of 18-crown-6.Their geometric and electronic structures were studied by single crystal X-ray diffraction,UV-vis,EPR,and superconducting quantum interference device(SQUID)measurements,in conjunction with DFT calculations.The study shows that the unpaired electrons of complexes[(18-c-6)K(THF)2]+·1·–and[(18-c-6)K(THF)2]+·2·–were delocated on the whole?system.The diradical dianion complexes[(18-c-6)K(THF)2]+[(18-c-6)K]+·12–··and[(18-c-6)K(THF)]22+·22–··are both open-shell singlet state in their ground states with small singlet-triplet energy gaps.Additionally,NOSb F6 was used to partially oxidate compounds 1 and 2 in the presence of Li[Al(ORF)4](RF=C(CF3)3),and two radical pimers,[13]2··+·[Al(ORF)4]2-and[22]·+·[Al(ORF)4]-were successfully isolated.Their geometric and electronic structures were studied by single crystal X-ray diffraction,UV-vis,EPR and flourescence,in conjunction with DFT calculations.The study reveals that[13]2··+·[Al(ORF)4]2-and[22]·+·[Al(ORF)4]-display flourescene both in solution and solid states.2.Reaction of the diazafluorenylidene-substituted phosphaalkene 3 with[Cp*2Ln][BPh4](Ln=DyIII,TbIII,GdIII)followed by subsequent reduction with KC8afforded complexes Cp*2Dy(N,N'-1)4,Cp*2Tb(N,N'-1)5 and Cp*2Gd(N,N'-1)6 in moderate yields,in which the phosphaalkene moiety is in the radical anion state.Complexes 4,5,6 represent the first lanthanide metal complexes of a heavy main-group element-based radical.They have been characterized by single crystal X-ray diffraction,UV/Vis spectroscopy and superconducting quantum interference device(SQUID)measurements.The magnetic studies reveal that the phosphorus radical center has a ferromagnetic interaction with the lanthanide ion in 4 and 5.Furthermore,complex 4shows slow magnetic relaxation behavior.3.The lanthanide complexes[Cp*2Ln][N,N'-bpy B](7:Ln=Dy III;9:Ln=Gd III;Cp*=pentamethylcyclopentadienyl)and[222-cryptand K][(Cp*2Ln)(N,N'-bpy B)](8:Ln=DyIII;10:Ln=GdIII)bearing the redox-noninnocent diborane ligand 5,5'-bis-(dimesitylboranyl)-2,2'-bipyridine(bpy B)have been syn-thesized through selective reduction of bpy B to the radical anion and diamagnetic dianion states with elemental potas-sium in the presence of[Cp*2Ln][BPh4],respectively.SQUID measurements revealed that the radical anions and the lan-thanide ions in 7 and 8 exhibit an antiferromagnetic interaction.Moreover,the effective energy barrier of magnetic relaxation for 7(18.5 K)is much smaller than that for 8(77.2 K)under a 1 KOe field,highlighting the potential of main-group element-based redox-noninnocent ligands in tuning single-molecule magnets. |
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