Yellow Arsenic as starting Material– Differences and Similarities in Its Reactivity to White Phosphorus

Investigating the reactivity of elementary white phosphorus is an actual area of research, taking both a sustainable and an atom-efficient direct path towards the synthesis of usable organo-phosphorus and inorganic phosphorus compounds. In contrast, the synthetic route to analogous, arsenic-containing compounds whose application potential is mainly in semiconductor technology always proceeds via AsCl3 and AsH3, respectively. To overcome the obvious deficit in the research of the usage of yellow arsenic as a starting material, our project focuses the investigation of the reaction behavior of yellow arsenic towards compounds of main group elements for which, so far, hardly any examples are known. This is crucial especially with regard to the prospectively high application potential of arsenic main group element compounds, and our corresponding knowledge has to be significantly enhanced. In the first instance, this field of application is subordinate to the general academic question of the access to and the principal characteristics of such main group element products and therefore has to be advanced in an explorative manner. Further, there is the question of the analogy and the differences in the reaction behavior between, on the one hand, As4 and, on the other hand, P4, under as much as possible identical conditions in order to evaluate as to whether their reactivity differs (based on the different E–E bond energies) and as to what extent different products become accessible. The mechanistic elucidation of the As4 activation is another central purpose of this project. To achieve the latter, it is necessary to trap and isolate transient species, as the 75As-NMR spectroscopy cannot be used to elucidate the reaction pathway. However, the comparative activation of the mixed tetrahedra PnAs4-n (n =1-3), in which one to three arsenic atoms were replaced by phosphorus atoms, presents a possibility to use the 31P-NMR spectroscopy instead. However, for the derivatives with n = 1 and 2, suitable synthetic routes with usable quantities have to be developed.