同结构Gd^ⅢM^Ⅱ(M=Cu,Ni,Co,Fe,Mn)配合物磁性理论研究

Magnetic Studies of Isomorphous Replacement of M^Ⅱ Ions in {Gd^ⅢM^Ⅱ}(M=Cu,Ni,Co,Fe,Mn) Complexes: A Theoretical Perspective

基于DFT-BS方法,在不同泛函方法和基组下计算[CuⅡGdⅢ{PyCO(OEt) Py C(OH)(OEt)Py}3]2+及3d-Gd异金属双核配合物的磁耦合常数,结果表明,PBE0/TZVP(Gd为SARC-ZDRA-TZVP)水平可用于描述其磁学性质。顺磁中心CuⅡ、GdⅢ与桥联配位氧原子间存在较强的轨道相互作用,其磁轨道主要由GdⅢ的4fIz3、4fz(x2-y2)轨道、CuⅠ的3dx2-y2轨道和桥联配位原子O的p轨道组成。顺磁中心CuⅡ离子以自旋离域作用为主,GdⅢ离子以自旋极化作用为主,顺磁中心CuⅡ自旋离域作用对桥联氧原子的影响大于顺磁中心GdⅢ的自旋极化作用。在同结构3d-Gd配合物中,随着MⅡ离子未成对电子的增加,顺磁中心间ρ2HS-ρ2BS越大,顺磁中心MⅡ和GdⅢ之间的反铁磁性贡献越大,其磁耦合常数越小。

The magnetic properties was studied for a series of {GdⅢMⅡ}(M=Cu, Ni, Co, Fe, Mn) heterobinuclear complexes by the combination of DFT calculations, using the different functional methods and basis sets, with the broken-symmetry approach. The results showed that the calculated values at the level of PBE0/TZVP(Gd is SARC-ZDRA-TZVP) are consistent with the experimental values, and this method can be used to describe its magnetic properties. There is a strong orbital interaction between the paramagnetic centers CuⅡ and GdⅢ and bridged coordination oxygen atoms. The molecular magnetic orbital of the complex [CuⅡGdⅢ{PyCO(OEt)Py C(OH)(OEt)Py}3]2+ are mainly contributed by 4fz3, 4fz(x2-y2) orbitals of the paramagnetic center GdⅢ, 3dx2-y2 orbital of CuⅡ ion and p orbitals of the bridging oxygen atoms. Due to the compensation of spin delocalization from CuⅡ ion and spin polarization from GdⅢ ion, the effect of spin delocalization from CuⅡ ion on bridged oxygen atoms is greater than the spin polarization effect of paramagnetic center GdⅢ ion. Model calculations were used to examine the influence of the electronic configuration of the MⅡ ions on the magnetic coupling constants. As a result, the increase of unpaired electrons of MⅡ ions, the ρ2HS-ρ2BS of the paramagnetic centers GdⅢ/MⅡincreases, the contribution of antiferromagnetic coupling increases, whereas the values of the magnetic coupling constant decreases.