Study On The Magnetic Coupling Mechanism Between Free Radical Complexes With Dmit As Ligand

In late more than a decade, the study on the intermolecular magnetic coupling mechanism has been one of the most studied topics in molecular magnetism research.Based on bistable spin transition property for radio compounds and its potential application in new molecular devices, it is very important in theory and practical application to perform the study on intermolecular magnetic coupling mechanism for radical compounds.This dissertation has designed and synthesized two new radical nickel complexes with dmit(1,3-dithiole-2-thione-4,5-dithiolate) as ligands, namely, complex [N-MePhen][Ni(dmit)2](1) and complex [Ni(2,2’-bpy)3][Ni(dmit)2]2(2), in which the counter cation in complex 1 is N-methyl-1,10-phenanthrolinium and in complex 2 is a nickel complex with bipyridine as ligand. The characterizations have been made for the two complexes and it includes infrared spectra, elemental analyses; single X-ray crystal structures also have been measured, which deals with three different temperatures, namely, room temperature, lower temperature(nearly 80 K) and low temperature(nearly 189 K); Based on the data of the crystal structures, the relevant data of interatomic short contact distances for the adjacent anionic radical complexes have been obtained in the three different temperatures; the variable temperature magnetic susceptibilities have been measured for the two complexes;Based on the data of the single crystal structures, the theoretical calculations have been performed and the relevant data of the spin densities and the SOMO interatomic overlap integral have also been obtained; the study on the correlation between temperature and spin densities on the atoms of radical anionic complexes has been made, and the study on the correlation between the antiferromagnetic coupling strength and the dominated factors has also been performed, in which the factors mean the spin density and the SOMO overlapintegral of short contact atomic pair. At the same time, the theoretical calculations have also been made on the reported radical complex [NO2 bzql][Ni(dmit)2]?CH3COCH3 that displays the behavior of the bistalbe spin transition. The theoretical calculations reveal the correlation among the spin transition, the SOMO overlap integral on the short contact atomic pair and the relevant antiferromagnetic coupling.The major contribution of this dissertation is as following two points.1. By theoretical calculations the correlation between temperature and the spin densities on the atoms of radical canionic Nickel complex with dmit as ligand has first been revealed.2. The correlation between the antiferromagnetic coupling strength and its relevant spin densities and SOMO’s overlap integral has first been revealed, in which the overlap integral means that of the short contact atomic pair of radical anionic nickel complexes with dmit as ligands.The achievement of this dissertation will certainly be beneficial for the designation and the synthesis of new kind of radical anionic complexes with behavior of bistable spin transition.