Magnetism of Organic Radical Complexes

分子内部或分子之间的磁相互作用通常是反铁磁性的。如果两个磁轨道，各有一个电子，距离足够近，可以相互作用，它们可以从反键轨道和成键轨道重叠。两个电子都以反平行自旋排列在成键轨道上。这种情况可以看作是化学键非常弱。然而，铁磁相互作用可以通过几种方式产生。例如，磁性轨道的正交排列可以导致高自旋态的稳定，这种情况在金属配合物和金属-金属配合物中被观察到。另一方面，顺磁中心之间通过抗磁性金属离子的磁相互作用很小或弱反铁磁性。已知一些抗磁性金属有利于四面体配位几何，这适合于两个双齿配体的正交排列。因此，我们预计两个双齿自由基配体的配位将导致自由基之间的铁磁相互作用。在本工作中，我们研究了中心金属离子为抗磁性的有机自由基配合物的磁性。我们发现铜(I)和银(I)离子的四面体配位几何导致配位自由基之间的铁磁相互作用，特别是铜(I)离子传播了相当强的铁磁相互作用（103 cm^<-1>）。

Magnetic interaction within or between molecules are typically antiferromagnetic. If two magnetic orbials, each having one electron, are sufficiently close to interact, they can overlap to from antibonding and bonding orbitals. Both electrons locate on the bonding orbital with anti-parallel spin alignment. This situation can be regarded as a very weak chemical bond. However, ferromagnetic interactions can arise in several ways. For example, Orthogonal arrangement of the magnetic orbitals can lead to stabilization of the high-spin state, sucsituation being observed for metal complexes and metal-redical complexes. On the other hand, magnetic interactions between paramagnetic centers through diamagnetic metal ions are negligibly small or weakly antiferromagnetic.Some diamagnetic metal ios are known to favor a tetrahedral coordination geometry which is suitable for the orthogonal arrangement of two bidentate ligands. Thus, it is anticipated that coordination of two bidentate radical ligands would lead to a ferromagnetic interaction between the radicals, In this work, we studied magneism of organic radical complexes whose central metal ions are diamagnetic. We have found that tetrahedral coordination geometries of copper (I) and silver (I) ions lead to the ferromagnetic interaction between coordinating radicals, especially the copper (I) ion propagate the fairly strong ferromagnetic intcraction (103 cm^<-1>).