Difluorophosphate

Difluorophosphate or difluorodioxophosphate or phosphorodifluoridate is an anion with formula PO2F−2. It has a single negative charge and resembles perchlorate (ClO−4) and monofluorosulfonate (SO3F−) in shape and compounds. These ions are isoelectronic, along with tetrafluoroaluminate, phosphate, orthosilicate, and sulfate. It forms a series of compounds. The ion is toxic to mammals as it causes blockage to iodine uptake in the thyroid. However it is degraded in the body over several hours. Difluorophosphate or difluorodioxophosphate or phosphorodifluoridate is an anion with formula PO2F−2. It has a single negative charge and resembles perchlorate (ClO−4) and monofluorosulfonate (SO3F−) in shape and compounds. These ions are isoelectronic, along with tetrafluoroaluminate, phosphate, orthosilicate, and sulfate. It forms a series of compounds. The ion is toxic to mammals as it causes blockage to iodine uptake in the thyroid. However it is degraded in the body over several hours. Compounds containing difluorophosphate may have it as a simple uninegative ion, it may function as a difluorophosphato ligand where it is covalently bound to one or two metal atoms, or go on to form a networked solid. It may be covalently bound to a non metal or an organic moiety to make an ester or an amide. The ammonium salt of difluorophosphate is formed from treating phosphorus pentoxide with ammonium fluoride. This was how the ion was first made by its discoverer, Willy Lange, in 1929. Alkali chlorides can react with dry difluorophosphoric acid to form alkali metal salts. Fluoridation of dichlorophosphates can produce difluorophosphates. Another method is fluorination of phosphates or polyphosphates. Trimethylsilyl difluorophosphate reacts with metal chlorides to give difluorophosphates. The anhydride phosphoryl difluoride oxide (P2O3F4) reacts with oxides such as UO3 to yield difuorophosphates. Phosphoryl difluoride oxide also reacts with alkali fluorides to yield difluorophosphates. In ammonium difluorophosphate the difluorophosphate ion has these interatomic dimensions: P–O length 1.457 Å, P–F length 1.541 Å, O–P–O angle 118.7°, F–P–O 109.4° and F–P–F angle 98.6°. Hydrogen bonding from ammonium to oxygen atoms causes a change to the difluorophosphate ion in the ammonium salt. In potassium difluorophosphate the ion has dimensions: P–O length 1.470 Å, P–F length 1.575 Å, O–P–O angle 122.4°, F–P–O 108.6° and F–P–F angle 97.1°. On heating the salts that are not of alkali or alkaline earths, difluorophosphates decompose firstly by giving off POF3 forming a monofluorophosphate (PO3F2−) compound, and then this in turn decomposes to an orthophosphate PO3−4 compound.