Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Kohoku-ku, Yokohama, Japan.
J Phys Chem B. 2011 Jul 7;115(26):8465-73. doi: 10.1021/jp111779k. Epub 2011 Jun 10.
The theoretical study of the magnetic properties of oxovanadium(IV) complex self-assemblies with tetradentate Schiff base ligands is discussed on the basis of DFT calculations. Large negative spin densities are found on the axial oxygens of the various oxovanadium(IV) complexes. The relationship between the effective exchange parameters J(ab) and the geometrical parameters for these complexes was studied by changing the position of the neighboring molecules for the purpose of clarifying the mechanism of the ferromagnetic coupling. The intermolecular ferromagnetic interaction of the oxovanadium(IV) complexes with tetradentate Schiff base ligands is significantly affected by the formation of polymeric octahedral structures in the solid state. The overlap between the 2p orbitals of the axial oxygen and the 3d orbitals of the adjacent vanadium is effective for the ferromagnetic coupling. On the other hand, the effect of overlap between the vanadium 3d(xy) orbitals is too small to lead to magnetic coupling. It was revealed that the intermolecular ferromagnetic interaction of the polynuclear oxovanadium(IV) complexes is significantly affected by the spin polarization on the axial oxygen.
基于密度泛函理论（DFT）计算，讨论了具有四齿席夫碱配体的氧钒（IV）配合物自组装的磁性理论研究。在各种氧钒（IV）配合物中，轴向氧上的自旋密度呈现出较大的负值。通过改变相邻分子的位置，研究了这些配合物的有效交换参数 J(ab)与几何参数之间的关系，目的是阐明铁磁耦合的机制。固态中聚合八面体结构的形成，显著影响了具有四齿席夫碱配体的氧钒（IV）配合物的分子间铁磁相互作用。轴向氧的 2p 轨道与相邻钒的 3d 轨道之间的重叠，对于铁磁耦合是有效的。另一方面，钒 3d(xy)轨道之间的重叠效应太小，不足以导致磁耦合。结果表明，多核氧钒（IV）配合物的分子间铁磁相互作用，显著受到轴向氧上的自旋极化的影响。
