 Illustrative PPN+ salts of reactive anions include PPN[HFe(CO)4], PPN[Co(CO)4], and PPN[Fe(CO)3NO].The role of ion pairing in chemical reactions is often clarified by examination of the related salt derived from PPN+.A phosphazenium cation related to PPN+ is {[(CH3)2N)3P]2N}+.