Diamidophosphate is the simplest phosphorodiamidate ion, with formula PO22−. It is a phosphorylating ion and was first used for phosphorylation of sugars in aqueous medium. Diamidophosphate can form salts such as sodium diamidophosphate, or an acid phosphorodiamidic acid. Phosphorodiamidic acid can crystallize as a trihydrate. It is hypothesized as a plausible primordial reagent in the emergence of the first peptides, cell membrane lipids and nucleotides, the precursors of all life on Earth. In a November 6, 2017 press release from the Scripps Research Institute, DAP was described as "a compound that may have been a crucial factor in the origins of life on Earth". Other nitrogenous derivatives of phosphorus derivatives have also been proposed in this context in a review article.
Production
Diamidophosphate compounds can be made from phenyl diamidophosphate reacting with sodium hydroxide in a water solution. This solution can crystallise sodium diamidophosphate. Phosphorodiamidic acid trihydrate can be precipitated from the solution by adding it to an excess of ethanol.
Reactions
The sodium saltcrystallises as a hexahydrate. It can be dehydrated by heating at 70°C for a week. When anhydrous sodium diamidophosphate is heated it polmerises. At 160°C Na2P2O42, Na3P3O622, Na4P4O832, Na5P5O1042 and Na6P6O1252 are produced. These substances contain a P-N-P backbone. These can be separated by paper chromatography. At 200°C heat the hexa-phosphate is the most common and at 250°C the typical chain length is 18. If hydrated salts are strongly heated they lose ammonia to form oligophosphates and polyphosphates. This compares with the heating of sodium amidophosphate, which yields sodium imidodiphosphate Na4P2O6NH and sodium nitridotriphosphate Na6P3O9N is produced also. Diamidophosphate binds to nickel ions, and inhibits urease enzymes by blocking up the active site, binding to two nickel atoms. Diamidophosphate mimics the urea hydrolysis intermediate. A silver AgPO22 and a potassium diamidophosphate salt KPO22 are also known. The silver salt can react using double decomposition with bromides forming other salts. Diamidophosphate can also be tribasic, and the amine groups may also lose hydrogen to form more metallic salts. With silver further reactions can yield explosive salts: tetrasilver orthodiamidophosphate 3PNHAg, and pentasilver orthodiamidophosphate 3P2. Numerous organic derivatives are known. Organic groups can substitute on the oxygen for the OH group, or replace a hydrogen on the amine group.
