Khalladi Ahmed, Kovalski Eduard, Abdulmalic Mohammad A, Rüffer Tobias, Yuan Qing, Naïli H, Korb Marcus, Lang Heinrich
Technische Universität, Research Centre for Materials, Architectures and Integration of Nanomembranes (MAIN), Research Group Organometallic Chemistry, Rosenbergstraße 6, D-09126 Chemnitz, Germany.
Technische Universität Chemnitz, Faculty of Natural Sciences, Institute of Chemistry, Inorganic Chemistry, D-09107 Chemnitz, Germany.
Dalton Trans. 2023 Dec 5;52(47):17717-17730. doi: 10.1039/d3dt00812f.
Dinuclear and trinuclear ferrocenylcarboxylato-bridged lanthanide complexes of type [Ln(μ:κ'-OCFc)(OCFc)(HO)(dmf)]·(dmf) (Ln = Sm (2), Eu (3), Gd (4), Tb (5); Fc = Fe(η-CH)(η-CH)), and novel [BuN][Ln(μ-OCFc)(μ:κ'-OCFc)(OCFc)(μ-OH)]·[BuN]Cl (Ln = Gd (6), Tb (7)) were prepared by the reaction of [LnCl·6HO] (synthesis of 2-5) or LnCl (synthesis of 6, 7) with FcCOH (1) in the ratio of 1 : 3. As evidenced by single crystal X-ray structure determination, in 2-5 the lanthanide ions are connected by symmetric FcCO units. In addition, two ferrocenylcarboxylato groups are μ-bridged to Ln. Each Ln ion is coordinated by nine oxygen donor atoms derived from one HO, one dmf and three carboxylates. The latter are found in chelating κ and bridging μ,κ coordination modes. Complexes 6 and 7 assemble three Ln cores around a central μ-netting hydroxide and nine FcCO entities. A combination of κ, μ,κ and μ,κ coordination modes results in an eight-fold coordination sphere for each metal, which is best described as bicapped trigonal prismatic. IR spectroscopy confirms the chelating and bridging motifs. Electrochemical studies of complexes 2-7 cyclic voltammetry (CV) and square-wave voltammetry (SWV) showed one redox event between °' = 250 and 260 mV FcH/FcH for 2-5 with all six FcCO redox events superimposed. Complexes 6 and 7 show a total of three events in the CV with the oxidations of the nine FcCO units occurring in close proximity. Deconvolution of individual redox events correlates well with the mononuclear complex [BuN][Gd(OCFc)]. UV-Vis/NIR spectroelectrochemical measurements of 7 did not reveal electron transfer between either Fc units, nor the coordinated lanthanides and resembled the absorption behavior of [BuN][Tb(OCFc)]. DFT (Density Functional Theory) calculations on the B3LYP def2-TZVP level of theory were carried out to assign the order of redox events in 6 showing that the spatial distance towards the most recent redox center, instead of the binding mode, is decisive.
[Ln(μ:κ'-OCFc)(OCFc)(HO)(dmf)]·(dmf)型（Ln = Sm (2)、Eu (3)、Gd (4)、Tb (5)；Fc = Fe(η-CH)(η-CH)）的双核和三核二茂铁基羧基桥联镧系配合物，以及新型的[BuN][Ln(μ-OCFc)(μ:κ'-OCFc)(OCFc)(μ-OH)]·[BuN]Cl（Ln = Gd (6)、Tb (7)）是通过[LnCl·6HO]（用于合成2 - 5）或LnCl（用于合成6、7）与FcCOH (1)按1∶3的比例反应制备的。单晶X射线结构测定表明，在2 - 5中镧系离子通过对称的FcCO单元相连。此外，两个二茂铁基羧基通过μ桥连到Ln上。每个Ln离子由来自一个HO、一个dmf和三个羧酸盐的九个氧供体原子配位。后者以螯合κ和桥连μ,κ配位模式存在。配合物6和7围绕一个中心μ-网状氢氧化物和九个FcCO实体组装了三个Ln核。κ、μ,κ和μ,κ配位模式的组合导致每个金属的八重配位球，最好描述为双帽三棱柱。红外光谱证实了螯合和桥连模式。配合物2 - 7的电化学研究（循环伏安法（CV）和方波伏安法（SWV））表明，对于2 - 5，在°' = 250至260 mV FcH/FcH之间有一个氧化还原事件，并叠加了所有六个FcCO氧化还原事件。配合物6和7在CV中总共显示三个事件，九个FcCO单元的氧化在相近电位发生。单个氧化还原事件的去卷积与单核配合物[BuN][Gd(OCFc)]相关性良好。7的紫外-可见/近红外光谱电化学测量未揭示任何一个Fc单元之间以及配位的镧系离子之间的电子转移，并且类似于[BuN][Tb(OCFc)]的吸收行为。在B3LYP def2-TZVP理论水平上进行了密度泛函理论（DFT）计算，以确定6中氧化还原事件的顺序，结果表明到最近氧化还原中心的空间距离而非键合模式起决定性作用。
