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

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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.