Singlet−Triplet Gap in Triplet Ground-State Biradicals Is Modulated by Substituent Effects
作者:David A. Shultz、Scot H. Bodnar、Hyoyoung Lee、Jeff W. Kampf、Christopher D. Incarvito、Arnold L. Rheingold
DOI:10.1021/ja020154+
日期:2002.8.1
semiquinones are attached 1,3 to a 5-substituted phenylene ring. The biradical complexes differ in their meta-substituents: 1-NMe(2)(), X = N,N-dimethylamino; 1-t-Bu, X = tert-butyl; 1-NO(2)(), X = nitro. All three structures have been determined by X-ray crystallography. Results of structural studies indicate that the biradical ligands of all three complexes have nearly identical conformations with
已经制备了三个 S = 1 双(半醌)配合物。为了确保铁磁分子内交换耦合,两个半醌以 1,3 的方式连接到 5-取代的亚苯基环。双自由基配合物的不同在于它们的间位取代基:1-NMe(2)(), X = N,N-二甲氨基;1-t-Bu,X = 叔丁基;1-NO(2)(),X = 硝基。所有三种结构均已通过 X 射线晶体学确定。结构研究的结果表明所有三个配合物的双自由基配体具有几乎相同的构象,平均半醌环扭转 32 度 +/- 2 度相对于 5 取代亚苯基环。交换参数 J (Eta = -2JS(1).S(2)) 的范围从 +31.0 +/- 0.6 cm(-)(1) 到 1-NO(2)() 到 +59.3 +/- 1.2 cm(-)(1) 对于 1-t-Bu,对于 1-NMe(2)(),J = +34.9 +/- 0.7 cm(-)(1)。由于构象几乎相同,交换耦合参数 J 的差异是由于取代基效应。实验结果得到了