The synthesis and thermal behaviour of magnesium bis(phosphorodiamidate)

Abstract

Magnesium bis(phosphorodiamidate) hexahydrate, Mg[PO₂(NH₂)₂]₂ · 6H₂O, was made by the wet process. The phosphorodiamidate was stable below 5° C, but it was converted to phosphoramidate, orthophosphate, and polyphosphates above 30° C in air. When the phosphorodiamidate was heated in air or in dry nitrogen at a higher temperature, it produced phosphoramidate, ortho- and polyphosphates, and polyphosphates with imino groups. The thermal products in air and in dry nitrogen finally gave Mg(PO₃)₂ associated with the following reaction at a higher temperature than about 700° C Mg[PO₂(NH₂)₂]₂·6H₂O→Mg(PO₃)+4NH₃+4H₂O and the product in dry nitrogen still contained 3 to 4% nitrogen.