Hexafluorophosphate

Hexafluorophosphate is an anion with chemical formula of PF−
6. This octahedral species is isoelectronic with sulfur hexafluoride, SF₆, and the hexafluorosilicate dianion, SiF₆, and is valence isoelectronic with the highly stable superacid anion fluoroantimonate SbF−
6. As a non-coordinating anion, it is a poor nucleophile. It is prone to decomposition with the release of hydrogen fluoride in ionic liquids but is generally extremely stable in solution. Hydrolysis to the phosphate ion is very slow even in concentrated acid with warming, and even slower under basic conditions.