Zhang Jing, Guo Shen-Zhen, Dong Yu-Bao, Rao Li, Yin Jun, Yu Guang-Ao, Hartl František, Liu Sheng Hua
Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University , Wuhan 430079, P. R. China.
Department of Chemistry, University of Reading , Whiteknights, Reading RG6 6AD, U.K.
Inorg Chem. 2017 Jan 17;56(2):1001-1015. doi: 10.1021/acs.inorgchem.6b02809. Epub 2017 Jan 3.
Homo-dinuclear nonlinear complexes [{M(dppe)Cp*}{μ-(-C≡C)X}] (dppe = 1,2-bis(diphenylphosphino)ethane; Cp* = η-CMe; X = triphenylamine (TPA), M = Ru (1a) and Fe (1b); X = N,N,N',N'-tetraphenylphenylene-1,4-diamine (TPPD), M = Ru (2a)) were prepared and characterized by H, C, and P NMR spectroscopy and single-crystal X-ray diffraction (1a, 2a). Attempts to prepare the diiron analogue of 2a were not successful. Experimental data obtained from cyclic voltammetry, square wave voltammetry, UV-vis-NIR (NIR = near-infrared) spectro-electrochemistry, and very informative IR spectro-electrochemistry in the C≡C stretching region, combined with density functional theory calculations, afford to make an emphasizing assessment of the close association between the metal-ethynyl termini and the oligophenylamine bridge core as well as their respective involvement in sequential one-electron oxidations of these complexes. The anodic behavior of the homo-bimetallic complexes depends strongly both on the metal center and the length of the oligophenylamine bridge core. The poorly separated first two oxidations of diiron complex 1b are localized on the electronically nearly independent Fe termini. In contrast, diruthenium complex 1a exhibits a significantly delocalized character and a marked electronic communication between the ruthenium centers through the diethynyl-TPA bridge. The ruthenium-ethynyl halves in 2a, separated by the doubly extended and more flexible TPPD bridge core, show a lower degree of electronic coupling, resulting in close-lying first two anodic waves and the NIR electronic absorption of [2a] with an indistinctive intervalence charge transfer character. Finally, the third anodic waves in the voltammetric responses of the homo-bimetallic complexes are associated with the concurrent exclusive oxidation of the TPA or TPPD bridge cores.
同双核非线性配合物[{M(dppe)Cp*}{μ-(-C≡C)X}]（dppe = 1,2-双（二苯基膦基）乙烷；Cp* = η-CMe；X = 三苯胺（TPA），M = Ru（1a）和Fe（1b）；X = N,N,N',N'-四苯基苯-1,4-二胺（TPPD），M = Ru（2a））已通过氢、碳和磷核磁共振光谱以及单晶X射线衍射（1a，2a）进行了制备和表征。制备2a的二铁类似物的尝试未成功。从循环伏安法、方波伏安法、紫外-可见-近红外（NIR = 近红外）光谱电化学以及在C≡C伸缩区域非常有用的红外光谱电化学获得的实验数据，结合密度泛函理论计算，能够对金属乙炔基末端与寡聚苯胺桥核之间的紧密关联以及它们各自在这些配合物的连续单电子氧化中的参与情况进行重点评估。同双金属配合物的阳极行为强烈依赖于金属中心和寡聚苯胺桥核的长度。二铁配合物1b的前两次氧化峰分离较差，位于电子上几乎独立的Fe末端。相比之下，二钌配合物1a表现出明显的离域特征，并且通过二乙炔基-TPA桥在钌中心之间存在显著的电子通信。2a中的钌-乙炔基半部由双延伸且更灵活的TPPD桥核隔开，显示出较低程度的电子耦合，导致前两个阳极波紧密相邻，以及[2a]的近红外电子吸收具有不明显的价间电荷转移特征。最后，同双金属配合物伏安响应中的第三个阳极波与TPA或TPPD桥核的同时排他性氧化有关。
