异自旋中心三自由基分子的磁性设计

Design of Tri-radical Ferromagnets with Heterospin Cen ters

采用量子化学DFTUB3LYP方法 ,在 6 31G(d)基组水平上讨论了以 1,3,5 苯为铁磁耦合单元的异自旋中心三自由基体系 .结果表明 :对于异自旋三自由基体系 ,形成异自旋后对称性降低使部分占据的近简并轨道能级劈裂值增大 ,反铁磁耦合作用普遍增强 .由两个同自旋和一个异自旋中心构成的三自由基若保持较好的对称性 (C2v)可望表现铁磁耦合 .在通常情况下这类分子服从已有规律 :ΔEPOMO小 ,ΔED Q大 ,表现为稳定的四重态基态 ,且其稳定性与苯环 2 ,4 。

A series of tri-radicals with heterospin center of 1, 3, 5-trisubstituted benzene as ferromagnetic coupling unit has been studied by using quantum chemical DFT UB3LYP method. The result shows that part-occupied near-degenerate orbitals split value and diaferromagnetic coupling increases when symmetry of hetero tri-radicals decreases. Ferromagnetic coupling can be obtained when the tri-radicals of two isospin and one heterospin center maintain the symmetry of C-2nu. Commonly, these molecules follow the rules that small DeltaE(POMO) and large DeltaE(D-Q) values lead to a stable quarlet ground state and the stability correlates to the 2,4,6-carbon position on benzene ring and the spin density of the radical atom.