Synthesis, Crystal Structure And Magnetic Properties Of Thio - Containing Anionic Ligand Complexes

Since the beginning of the fifty’s of last century, the study of molecular magnetic property has been one of important subjects in area of chemistry and physics. Especially since the beginning of the eighty’s of last century, the study of molecular magnetic property has been one of frontier subjects in coordination chemistry. The much attention has been paid in the study of molecular magnetic property of radical complexes for recent two decades. The reason is that this kind of complexes exhibited bi-stable spin-transition property, which are attributes of molecular switches and may lead to utilities in molecular electronics for memory or sensing applications.The reported radical complexes are mainly constituted anionic divalent alkene-dithiolate, such as dmit(1,3-dithiole-2-thione-4,5-dithiolate) and mnt(cis-1,2-dicyanoethylene-1,2-dithiolate), as ligands, and nickel, palladium and platinum as central ions to date. Similar to dmit and mnt, tdas(1,2,5-thiadiazole-3,4-dithiolate) is also a kind of anionic divalent alkene-dithiolate ligand dealing with radical complexes. But few this kind of complexes have been reported to date, and only one complex dealing with molecular magnetism has been published to our best knowledge. In addition, the structure-property of cobalt complexes with mnt as ligand has not been understood thoroughly. Based on information above, The five new complexes have been designed and synthesized with tdas and mnt as ligands and nickel and cobalt as central ions in this dissertation, namely, two novel dinuclear radical anionic nickel complexes [Ni(tdas)2]22-×, which N-H-pyridinium and N-methyl-pyridinium as counter-cations, respectively; three new dinuclear cobalt anioniccomplexes [Co(mnt)2]22-, which N-H-pyridinium, tetrabutylammonium and N-(4-chlorobenzyl)-pyridinium as counter-cations, respectively. The characterization with IR,elemental analysis and x-ray single crystal determination has been made for the five new complexes. For the two radical nickel complexes, the properties dealing with thermal analysis and ESR spectra at room temperature in solid state and in the solution have been performed, and theoretical calculations have also been performed. The information dealing with magnetic coupling strength and the factors that dominate magnetic coupling strength,such as spin densities, have been obtained at the first time; the study also deals with the magnetic coupling information and its relevant molecular forces for the two novel radical nickel complexes. For the three new cobalt complexes, the correlation between the coordinated structure and the magnetic properties has also been studied. The obtained information from this dissertation will benefit the synthesis and the study of the magnetic property of the new radical complexes, and especially this dissertation will benefit designing and synthesizing new ideal bi-stable spin transition complexes.