The Magnetic Mechanism Studies Of Coordination Compounds

The density function theory gives a firmly theoretical foundation for the study of ground states of materials. The first-principles calculation based on the density function theory has become one of the most powerful tools for the study of ground states in condensed matters. With the first-principles calculation, we can not only get the ground state properties of materials, but also simulate their behaviors under different conditions. This means that we can predict novel properties of materials or design the required materials.To obtain the macromagnetism of organic compounds, the appropriate steric arrange of molecules is important in addition to the paramagnetic centers, for the purpose of the coupling of spin magnetic moments between the paramagnetic centers. So controlling the molecule arrange in the crystals is critical for the design and synthetise of organic magnetic compounds. On the basis of above thinking, a lot of organic-metallic coordination compounds are obtained. However, these researches focus attention on the structure-magnetism relation of crystals, not involve the magnetic origin and magnetic mechanism of materials which is indispensable for revealing the coupling mechanism of metal ions through bridge ligands in magnetic materials.The purpose of this paper is using the first principles based on the density functional theory calculations to study the electronic structure and spin magnetic moments distribution of several coordination compounds, in order to reveal the metal ions through ligand coupling mechanism of the magnetic, which is important for understanding the magnetic origin and magnetic mechanism. In the calculation, we choose based on full-potential linearized augmented plane wave method WIEN2k code, which is one of the most accurate methods for performing electronic structure calculations for crystals.First, the first-principles method was applied to study the electronic structure and magnetic properties of MnCu(pba)(H2O)3·2H2O compound. According to the calculated results, there are two magnetic centers (Cu and Mn ions) in the compound. The Cu-bridge interactions exhibit significant covalent character, while the Mn-bridge interactions are mainly closed-shell interplay. There are strong intrachain interactions and weak interchain couplings. Magnetic coupling exhibits the spin delocalization effect from Mn and Cu atoms to the bridging atoms, and does not reveal metallically magnetic properties. Secondly, the first principle method was applied to study the electronic structure and magnetic properties of the compound of Co(endi)2(N3)2. According to the calculations, there is ferromagnetic interaction between the compound, and the magnetic coupling comes from Co2+ to the azide ligand spin delocalization effect. Also it reveal semi-metallically magnetic properties.Finally, the 2,2'-bipyridine ligands compounds were also studied. It can be seen from the magnetic moment distribution of the compound of Cu(μ-cbdca)(bpy)2, there are the largest magnetic moment distribution on Cu atoms and a small magnetic moment on bipyridine ligand. It indicates that there is ferromagnetic coupling between Cu atoms and the bipyridine ligand, and the ferromagnetic coupling comes from Cu atoms to the bipyridine ligand spin delocalization effect, but does not reveal metallically magnetic properties.