In-situ characterisable nitrosyl-iron complexes with controllable reactivity in multiphasic reaction media

铁（II）盐溶液与一氧化氮（NO）反应形成亚硝基配合物。亚硝基化产物的形成可以通过光学和振动光谱检测。液相是亚铁盐的水溶液。在与一氧化氮反应时，形成亚硝基-铁键，其稳定性可通过添加共配体来调节。多齿螯合剂如乙二胺四乙酸酯（edta）诱导铁（NO）功能对NO损失的显著电阻率。在第一个资助期，亚硝基胺配合物的结构化学建立了一系列属于胺羧酸类的共配体，如edta。因此，铁(II)/氨基羧酸盐/亚硝基配合物的结构-性质关系变得切实可见，例如配位数变化对no结合的影响。因此，为进一步发展含铁水相与反应气体NO的非均相反应提供了坚实的基础。具体而言，未来发展的化学部分侧重于构建具有进一步增强性能的新配体，包括两个目标。首先，我们将尝试全面提高配合物的稳定性，以允许在低一氧化氮分压下可靠地吸收一氧化氮，包括以一氧化氮为次要成分的气体混合物的研究。其次，我们将尝试通过设计新的配体来实现NO-与o2的选择性结合，这些配体可以完美地协调NO结合前后的铁基中心。第二个问题不仅具有学术意义，而且解决了用于从烟气流中剥离NO的技术上使用的铁(II)/edta溶液的恼人副反应，即铁（II）试剂不可逆氧化到铁（III）氧化态。如果我们通过优化化学参数成功地抑制了不可逆氧化，则可以使用气泡柱技术最终促进所需的NO吸收反应。在第一个资助期内，证明了在甲醇作为溶剂时，即使使用纯NO作为反应气体也会导致竞争性反应序列，即形成铁和钴的单硝基或二硝基。我们计划开发一种反应系统，使我们能够通过改变气泡柱参数来研究对两种反应之一的选择性。总之，除了继续使用颜色强烈的亚硝基隆配合物来研究和模拟气泡柱中的反应外，我们的目标是开发两个新的领域：一方面控制亚硝基化和氧化之间的竞争，另一方面控制单硝基或二硝基的形成。

Iron(II) salt solutions react with nitric oxide (NO) as a reactive gas under formation of nitrosyliron complexes. The formation of the nitrosylated products can be detected by optical and vibrational spectroscopy. The liquid phase is an aqueous solution of a ferrous salt. On reaction with nitric oxide, a nitrosyl-iron linkage is formed, the stability of which can be adjusted by the addition of co-ligands. Multidentate chelators such as ethylenediaminetetraacetate (edta) induce pronounced resistivity of the Fe(NO) functions towards NO loss. In the first funding period, the structural chemistry of nitrosyliron complexes was established for a series of co-ligands that belong to the class of aminecarboxylates, as does edta. As a result, structure-property relationships within the class of iron(II)/aminecarboxylate/nitrosyl complexes have become tangible, such as the consequences of coordination-number changes on NO-binding. Thus, a solid basis is available to further develop the heterogeneous reaction of an iron-containing aqueous phase and the reactive gas NO. Specifically, the chemical part of future development focuses on the construction of new ligands with further enhanced properties and includes two goals. First, we will attempt to produce an overall increase of the complexes' stability to allow for reliable NO absorption at low nitric-oxide partial pressures to include the investigation of gas mixtures with NO as the minor component. Second, we will try to achieve selective NO- over O2-binding by designing new ligands that perfectly coordinate the ferrous centres before and after NO binding. This second issue is not only of academic interest but addresses an annoying side-reaction of technically employed iron(II)/edta solutions used for the stripping of NO from flue-gas streams, namely the irreversible oxidation of the iron(II) reagent to the iron(III) oxidation state. If we succeed in repressing the irreversible oxidation by the optimisation of chemical parameters, bubble-column technology may be used to finally promote solely the desired NO absorption reaction. In the first funding period, it was demonstrated that, in methanol as the solvent, even the use of pure NO as the reactive gas could result in competing reaction sequences, namely the formation of either mononitrosyls or dinitrosyls of iron and cobalt. We plan to develop a reaction system that allows us to study the selectivity towards one of the two reactions by the variation of bubble-column parameters. In summary, besides continuing to use the intensely coloured nitrosyliron complexes for the study and modeling of the reactions in bubble columns, we aim to develop two new fields: the control of the competition between nitrosylation and oxidation on the one hand, and the control of the formation of either mononitrosyls or dinitrosyls on the other.