The analytical and descriptive inorganic chemistry of the hydrolysis of hexafluoropnictate ions, PnF6− (Pn = P, As, Sb, Bi)

The rates of aqueous hydrolysis of the hexafluoropnictate ions, PnF6− (Pn=P, As, Sb, Bi) were determined using a fluoride ion selective electrode and understood qualitatively in terms of ionic size and polarizability of the central atom. Both SN2 and SN1 (i.e. associative and dissociative) hydrolysis are discussed as are the competing roles of acid and base in the reaction. (Valence) isoelectronic analogies are also given. Regardless of the interpretation or reaction conditions, it is unequivocal that the hydrolysis rate is measurably rapid for the hexafluoroantimonate. By contrast, it is negligible for both hexafluorophosphate and hexafluoroarsenate.