Sil Amit, Ghosh Utsav, Mishra Vipin Kumar, Mishra Sabyashachi, Patra Sanjib K
Department of Chemistry , Indian Institute of Technology Kharagpur , Kharagpur - 721302 , West Bengal , India.
Inorg Chem. 2019 Jan 22;58(2):1155-1166. doi: 10.1021/acs.inorgchem.8b02440. Epub 2019 Jan 7.
A series of heterobimetallic wire-like organometallic complexes [( tpy-CH-R)(PPh)Ru-C≡C-Fc] ( tpy-CH-R = 4'-(aryl)-2,2':6',2''-terpyridyl, Fc = [(η-Cp)Fe], R = -H, -Me, -F, -NMe in complexes 5-8, respectively) featuring ferrocenyl and 4'-(aryl)-2,2':6',2''-terpyridyl ruthenium(II) complexes as redox active metal termini, have been synthesized. Various spectroscopic tools, such as multinuclear NMR, IR spectra, HRMS, CHN analyses, and single crystal X-ray crystallography have been utilized to characterize the heterobimetallic complexes. The electrochemical and UV-vis-NIR spectroscopic studies have been investigated to evaluate the electronic delocalization across the molecular backbones of the Ru(II)-Fe(II) heterobinuclear organometallic dyads. Electrochemical studies reveal two well-separated reversible redox waves as a result of successive oxidation of the ferrocenyl and Ru(II) redox centers. The spin density distribution analyses reveal that the initial oxidation process is associated with the Fe(II)/Fe(III) couple followed by one electron oxidation of the ruthenium(II) center. The high K value (0.11-1.73 × 10) and intense NIR absorption, with molar absorption coefficient (in the order of 10 M cm) for the RuFe mixed-valence species, signify strong electronic communication between the two metal termini. The electronic coupling constant ( H) has been estimated to be 492 and 444 cm for the structurally characterized complexes 6 and 7, respectively. The redox and NIR absorption features indicate that the mixed-valence system of the heterobinuclear dyads belongs to a Robin and Day "class II" system.
一系列具有二茂铁基和4'-(芳基)-2,2':6',2''-三联吡啶钌(II)配合物作为氧化还原活性金属末端的异双核线状有机金属配合物[(tpy-CH-R)(PPh)Ru-C≡C-Fc]（在配合物5-8中，tpy-CH-R分别为4'-(芳基)-2,2':6',2''-三联吡啶，Fc = [(η-Cp)Fe]，R = -H、-Me、-F、-NMe）已被合成。已利用多种光谱工具，如多核NMR、红外光谱、高分辨质谱、CHN分析和单晶X射线晶体学来表征这些异双核配合物。已开展电化学和紫外-可见-近红外光谱研究，以评估Ru(II)-Fe(II)异双核有机金属二元体系分子主链上的电子离域情况。电化学研究表明，由于二茂铁基和Ru(II)氧化还原中心的连续氧化，出现了两个分离良好的可逆氧化还原波。自旋密度分布分析表明，初始氧化过程与Fe(II)/Fe(III)电对相关，随后是钌(II)中心的单电子氧化。对于RuFe混合价态物种，高K值（0.11 - 1.73×10）和强烈的近红外吸收，以及摩尔吸收系数（约为10 M cm），表明两个金属末端之间存在强电子通信。对于结构表征的配合物6和7，电子耦合常数（H）估计分别为492和444 cm。氧化还原和近红外吸收特征表明，异双核二元体系的混合价态系统属于罗宾和戴“II类”系统。
