Magnetism of Organic Radical Complexes

分子内或分子间的磁相互作用通常是反铁磁的。如果两个磁性轨道，每个都有一个电子，足够接近相互作用，它们可以重叠形成反键和成键轨道。两个电子都位于反平行自旋排列的成键轨道上。这种情况可以被认为是一种非常弱的化学键。然而，铁磁相互作用可以以几种方式出现。例如，磁轨道的正交排列可以导致高自旋态的稳定，这种情况在金属络合物和金属-自由基络合物中观察到。另一方面，通过抗磁性金属离子的顺磁性中心之间的磁相互作用是可以忽略不计的小或弱反铁磁性。已知一些抗磁性金属离子倾向于四面体配位几何结构，这适合于两个双齿配体的正交排列。因此，可以预料，两个双齿自由基配体的配位将导致自由基之间的铁磁性相互作用。在这项工作中，我们研究了有机自由基配合物的磁性，其中心金属离子是抗磁性的。我们发现铜（I）和银（I）离子的四面体配位构型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 ~ 2<-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>).