31P nuclear magnetic resonance chemical shifts of elemental phosphorus in the gas phase

Facile storage and release of white phosphorus and yellow arsenic

The storage of metastable compounds and modifications of elements are of great interest for synthesis and other, e.g., semiconductor, applications. Whereas white phosphorus is a metastable modification that can be stored under certain conditions, storage of the extremely (light- and air-)sensitive form of arsenic, yellow arsenic, is a challenge rarely tackled so far. Herein, we report on the facile storage and release of these tetrahedral E₄ molecules (E = P, As) using activated carbon as a porous storage material. These loaded materials are air- and light-stable and have been comprehensively characterized by solid-state ³¹P{¹H} MAS NMR spectroscopy, powder X-ray diffraction analysis, nitrogen adsorption measurements, and thermogravimetric analysis. Additionally, we show that these materials can be used as a suitable E₄ source for releasing intact white phosphorus or yellow arsenic, enabling subsequent reactions in solution. Because the uptake and release of E₄ are reversible, these materials are excellent carriers of these highly reactive modifications.

On the molecular and electronic structures of AsP3 and P4

The molecular and electronic structures of AsP(3) and P(4) have been investigated. Gas-phase electron diffraction studies of AsP(3) have provided r(g) bond lengths of 2.3041(12) and 2.1949(28) A for the As-P interatomic distances and the P-P interatomic distances, respectively. The gas-phase electron diffraction structure of P(4) has been redetermined and provides an updated value of 2.1994(3) A for the P-P interatomic distances, reconciling conflicting literature values. Gas-phase photoelectron spectroscopy provides experimental values for the energies of ionizations from the valence molecular orbitals of AsP(3) and P(4) and shows that electronically AsP(3) and P(4) are quite similar. Solid-state (75)As and (31)P NMR spectroscopy demonstrate the plastic nature of AsP(3) and P(4) as solids, and an extreme upfield (75)As chemical shift has been confirmed for the As atom in AsP(3). Finally, quantum chemical gauge-including magnetically induced current calculations show that AsP(3) and P(4) can accurately be described as strongly aromatic. Together these data provide a cohesive description of the molecular and electronic properties of these two tetraatomic molecules.