氰酸根桥联双核铜配合物磁构效关系的密度泛函研究

DFT Studies on the Magneto-Structural Relations of the Pseudohalide Cyanate Bridging Copper (II) Dimers

在密度泛函理论的框架下,采用对称性破损态方法,以{Cu2(C2H4N2)2(N, N-μ-NCO)2}2+为模型化合物,研究氰酸根EO方式桥联双核铜配合物的磁构效关系,进一步证实了通过CuNCu间的三中心d-p-dσ反键的超交换作用与磁偶合构效关系的本质联系. 计算了氰酸根桥联配合物磁交换偶合常数J与桥联角θ的关系,并与叠氮酸桥联配合物进行了比较.

On the basis of the broken symmetry approach and density functional theory (DFT), the magnetostructural characterization of cyanato-bridged Cu (II) dimers in EO coordination mode has been studied. The calculated results indicate further that the essence of the magneto-structure characterization of pseudohalide-bridged Cu (II) dimers lies in d-p-d three centers sigma antibonding action between two Cu d(xy) orbits and bridged N p(x) orbit in SOMO b(g). Simultanously it is shown that the exchange coupling constant J of cyanato-bridged copper (II) dimers is larger than that of azido-bridged Cu (II) dimers, which is due to the decrease of the antiferromagnetical terms in Hoffmann's formula as the increase of the electronegativities of substituents connected with the bridging atoms.