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

本计画旨在利用烯基或苯乙烯基修饰的二茂铁及三芳胺的自由基阳离子，探讨不对称混合价化合物中部分电子与全电子之间的边界区域及自旋离域。这两种化合物具有两个强耦合，但化学上不同的氧化还原位点，其固有的氧化还原电位可以独立地通过在二茂铁或三芳胺亚基或共配体在钌网站的引入合适的取代基而变化。这将使我们能够直接影响潜在的超曲面上的局部极小值的垂直偏移，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，两种氧化还原活性亚基将提供指示性IR或EPR可寻址光谱标签，其提供在固有不同时间尺度的相应位点处的电荷和自旋密度的定量测量。有了这些化合物在手，我们将解决以下问题：-如何氧化还原分裂之间的两个氧化还原波和程度的电荷和自旋离域在电子基态的混合价形式的这些化合物的影响，在不同的内在氧化还原电位的个别网站？-我们能否通过分析不同电荷敏感IR标记物的光谱位移和这些分子内不同自旋密度标记物的超精细分裂模式的分析，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？氧化还原不对称性如何影响混合价阳离子自由基低能电子吸收带的位置、强度和半宽？我们能否通过比较该电子带的特征参数与来自IR和EPR光谱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？我们能否确定控制原子价（去）定域的环境效应，以及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?