Study On The Magnetic Coupling Properties Between Complex Radicals

The study of magnetic coupling property among adjacent radical molecules is one of frontiers in molecule-based magnetism.Some radical complexes have display special spin transition property,which are attributes of molecular switches and may lead to utilities in molecular electronics for memory or sensing applications.Therefore,performing study in magnetic coupling mechanism between adjacent radical complexes possess important meaning in theoretical field and applying field.In this dissertation,four unpublished radical complexes have been designed and synthesized with dmit(1,3-dithiole-1,2-thione-4,5-dithiolate)and mnt(cis-1,2-dicyanothylene-1,2-dithiolate)as ligands,namely,complexes [N-MePhen-OCH3][Ni(dmit)2],[Ni(phen)3][Ni(dmit)2]2CH3COCH3,[Ni(2,2’-bpy)3][Ni(mnt)2]2 and [Ni(phen)3][Ni(mnt)2]2CH3CN.The characterizations deal with IR,XRD,elemental analysis;their crystal structures determined by X-ray crystallography at room temperature and lower temperature.The variable temperature magnetic susceptibilities(5 K – 330 K)of the former three complexes have been measured;The short contact interactions between the adjacent coordinated anions have been obtained by the relevant crystal data;the spin densities on the short contact atoms and the SOMO overlap integral values have also been obtained by theoretical calculations;the corelation among the magnetic coupling strength and the spin densities and the overlap integral values have been studies and the important results have been obtained,namely:1.It is first revealed that the larger overlap integral absolute value between short contact atoms will result in the stronger antiferromagnetic coupling strength.2.It is first revealsed that the spin density on the ?-? stacking short contact atomic pair and their overlap integral are the main factors that result in the antiferromagnetic coupling strength.3.It is further confirmed that the one of dominated factors of induced strong antiferromagnetic coupling strength between adjacent coordinated radical anions is that spin density on the short contact atomic pair should be larger than 0.1.The studied results of this dissertation will possess important meaning in designing and synthesizing ideal devices of molecular electronics for memory or sensing applications.