A High-Pressure Polymorph of Phosphorus Nitride Imide

Phosphorus nitride imide, PN(NH), is of great scientific importance because it is isosteric with silica (SiO2). Accordingly, a varied structural diversity could be expected. However, only one polymorph of PN(NH) has been reported thus far. Herein, we report on the synthesis and structural investigation of the first high-pressure polymorph of phosphorus nitride imide, -PN(NH); the compound has been synthesized using the multianvil technique. By adding catalytic amounts of NH4Cl as a mineralizer, it became possible to grow single crystals of -PN(NH), which allowed the first complete structural elucidation of a highly condensed phosphorus nitride from single-crystal X-ray diffraction data. The structure was confirmed by FTIR and P-31 and H-1 solid-state NMR spectroscopy. We are confident that high-pressure/high-temperature reactions could lead to new polymorphs of PN(NH) containing five-fold- or even six-fold-coordinated phosphorus atoms and thus rivalling or even surpassing the structural variety of SiO2.