A new approach to the cooperative activation and transformation of elementary phosphorus

元素磷是制备大多数有机磷化合物的起始原料，探索由元素磷直接合成有机磷化合物的可持续方法具有重要的理论意义和应用价值。在这个项目中，我们将进一步推进最近发现的一个反应，在该反应中，一个空间上不受阻碍的N-杂环卡宾(NHC)和一个弱酸同时作用，导致形式歧化下的P4-四面体分解为两个不同的P1-构造块(“咪唑酰膦”)。通过对反应条件的优化，以机理研究的结果为指导，我们打算抑制副产物的形成，并更好地接近磷的定量转化。此外，我们将开发反应，在回收所用的NHC试剂的情况下，将生成的P1构筑块转化为功能化的亲电有机磷化合物(例如有机磷卤化物)。由各种单独转化的连接产生的反应网络将建立新的简单的途径来合成有价值的目标化合物，并将允许识别反应循环，这可能作为催化反应变体的长期开发的基础。在这些活性过程中研究的简单咪唑基膦的取代反应也将被用于组装可能用作多齿或大环配体的多官能团衍生物。在配位化学的初步研究过程中，我们将探索这些配体对动力学惰性双金属或多金属配合物的稳定作用。

Elemental phosphorus is the starting material for the preparation of most organophosphorus compounds, and the exploration of sustainable methods for their straight synthesis from the element is consequently of paramount interest in both academic and applied research. In this project, we will further advance a recently discovered reaction in which the simultaneous action of a sterically unhindered N-heterocyclic carbene (NHC) and a weak acid induces dismantling of the P4-tetrahedron under formal disproportionation into two different P1-building blocks ("imidazoyl phosphinidenes"). By carrying out an optimization of the reaction conditions that is directed by the results of mechanistic studies, we intend to suppress the formation of side products and preferably approach quantitative conversion of the phosphorus. In addition, we will develop reactions which allow transformation of the resulting P1-building blocks into functionalized electrophilic organophosphorus compounds (e. g. organophosphorus halides), under recovery of the NHC reagents employed. The reaction network arising from the connection of the various individual transformations will establish novel simple access routes to synthetically valuable target compounds and will permit to identify reaction cycles which may serve as the basis for a long-term development of catalytic reaction variants. Substitution reactions at simple imidazoyl phosphinidines, which are studied in the course of these activities, will also be employed for the assembly of polyfunctional derivatives that may serve as possible multidentate or macrocyclic ligands. In the course of first studies of the coordination chemistry, we will explore the use of these ligands for the stabilization of kinetically inert bi- or multimetallic complexes.