Alkenylruthenium ferrocenyl and triarylamine conjugates for the quantitative analysis of electronic coupling in unsymmetrical mixed-valent compounds at the Class II/III borderline

本项目旨在利用烯基或芳基修饰的二茂铁和三芳胺的自由基阳离子来探索不对称混合价化合物中部分和完全电子和自旋离域之间的边界区域。这两种化合物都具有两个强耦合但化学性质不同的氧化还原位点，其固有的氧化还原电位可以通过在二茂铁或三芳胺亚基或钌位点的共配体上引入合适的取代基而独立改变。这将使我们能够直接影响势超表面上局部极小值的垂直偏移量，从而影响相应的混合价自由基阳离子基态的价离域程度。此外，这两种氧化还原活性亚基都将提供指示性IR或EPR可寻址光谱标签，这些标签可以在固有的不同时间尺度上对各自位点的电荷和自旋密度进行定量测量。有了这些化合物，我们将解决以下问题：-两个氧化还原波之间的氧化还原分裂以及这些化合物的混合价形式的电子基态中电荷和自旋离域的程度如何受到单个位点内在氧化还原电位差异的影响？-我们能否通过分析不同电荷敏感红外标记的光谱位移和分析这些分子中不同自旋密度标记的超精细分裂模式，获得单个氧化还原位点上电荷和自旋密度分布的一致图像？-氧化还原不对称性对混合价自由基阳离子低能电子吸收带的位置、强度和半宽度有何影响？-我们能否通过比较该电子带的特征参数与从IR和EPR光谱中得到的电荷和自旋离域的定量信息，获得一种确定这种混合价体系中有效电荷转移距离的方法？-我们能否确定控制价（去）定位的环境影响，我们能否利用它们从一种转换到另一种？

This project aims at utilizing the radical cations of alkenyl- or styryl-modified ferrocenes and triarylamines to explore the borderline region between partial and full electron and spin delocalisation in unsymmetrical mixed-valent compounds. Both kinds of compounds feature two strongly coupled, yet chemically different redox sites, whose intrinsic redox potentials can be independently varied by the introduction of suitable substituents at the ferrocene or triarylamine subunit or the coligands at the ruthenium site. This will allow us to directly influence the vertical offset of the local minima on the potential hypersurface and hence the degree of valence delocalisation in the ground state of the corresponding mixed-valent radical cations. Furthermore, both redox-active subunits will offer indicative IR or EPR addressable spectroscopic tags which provide quantitative measures of the charge and spin densities at the respective sites at inherently different timescales. With these compounds in hand we will address the following issues:- How are the redox-splitting between the two redox waves and the degree of charge and spin delocalisation in the electronic ground state of the mixed-valent forms of these compounds affected by the difference in the intrinsic redox potentials of the individual sites?- Can we obtain a congruent picture of charge and spin density distributions over the individual redox sites by analyzing the spectroscopic shifts of different charge-sensitive IR markers and the analysis of the hyperfine splitting patterns to different spin density markers within these molecules?- How are the position, the intensity and the half-width of the low energy electronic absorption bands of the mixed-valent radical cations affected by the redox asymmetry?- Can we obtain a method for determining the effective charge-transfer distance in such mixed-valent systems by comparing the characteristic parameters of that electronic band with the quantitative information on charge and spin delocalisation derived from IR and EPR spectroscopy?- Can we identify environmental effects that control valence (de)localization and can we utilize them for switching from one to the other?