Hou Chao, Shi Jing-Min, Sun You-Min, Shi Wei, Cheng Peng, Liu Lian-Dong
College of Chemistry, Chemical Engineering and Materials Science, Engineering Research Center of Pesticide and Medicine Intermediate Clean Production, Ministry of Education, Shandong Normal University, Jinan 250014, P. R. China.
Dalton Trans. 2008 Nov 21(43):5970-6. doi: 10.1039/b803621g. Epub 2008 Sep 16.
An anomalous magnetic interaction is observed in a very common and unpublished binuclear copper(ii) complex, [Cu(2)(micro(2)-OOCCH(3))(2)(bpydiol-H)(2)(H(2)O)(2)] (bpydiol-H = mono deprotonated 2,2'-bypyridine-3,3'-diol). In the complex, the two Cu(ii) ions are bridged by two acetate anions and there is a pi-pi stacking interaction between the adjacent pyridine rings. Theoretical calculations reveal that the acetate bridge ligand leads to an antiferromagnetic coupling with 2J = -166.72 cm(-1), whereas the pi-pi stacking developed a ferromagnetic interaction with 2J = 21.0 cm(-1). The offset from the antiferromagnetic interaction and the ferromagnetic interaction may be one of main factors that resulted in the weaker magnetic coupling with experimental fitting 2J = -59.61 cm(-1). This is the first example using theoretical calculations that evaluate the magnetic coupling intensity for a pi-pi stacking system.
在一种非常常见但未发表的双核铜（II）配合物[Cu(2)(μ(2)-OOCCH(3))(2)(bpydiol-H)(2)(H(2)O)(2)]（bpydiol-H = 单去质子化的2,2'-联吡啶-3,3'-二醇）中观察到异常的磁相互作用。在该配合物中，两个铜（II）离子由两个醋酸根阴离子桥连，相邻吡啶环之间存在π-π堆积相互作用。理论计算表明，醋酸根桥连配体导致反铁磁耦合，2J = -166.72 cm(-1)，而π-π堆积产生铁磁相互作用，2J = 21.0 cm(-1)。反铁磁相互作用和铁磁相互作用之间的抵消可能是导致实验拟合的磁耦合较弱（2J = -59.61 cm(-1)）的主要因素之一。这是使用理论计算评估π-π堆积体系磁耦合强度的首个实例。
