ations , ▁R 2 F + ▁dich lor of lu or on ium , ▁Cl 2 F + ▁trif lu or ox en on ium , ▁X e F ▁( X e F 2 ▁is ▁neutral .) ▁ ▁O ni um ▁c ations ▁with ▁poly val ent ▁substitution s ▁secondary ▁am mon ium ▁c ations ▁having ▁one ▁double - b ond ed ▁substitution , ▁R = N H 2 + ▁dia zen ium , ▁H N = N H 2 + ▁( pro ton ated ▁dia z ene ) ▁gu an id in ium , ▁( H 2 N ) 2 C = N H 2 + ▁( pro ton ated ▁gu an id ine ) ▁( has ▁a ▁reson ance ▁structure ) ▁qu atern ary ▁am mon ium ▁c ations ▁having ▁one ▁double - b ond ed ▁substitution ▁and ▁two ▁single - b ond ed ▁substitution s , ▁R = NR 2 + ▁im in ium , ▁R 2 C = NR 2 + ▁( subst it uted ▁pro ton ated ▁im ine ) ▁dia zen ium , ▁R N = NR 2 + ▁( subst it uted ▁pro ton ated ▁dia z ene ) ▁qu atern ary ▁am mon ium ▁c ations ▁having ▁two ▁double - b ond ed ▁substitution s , ▁R = N = R + ▁nit ron ium , ▁NO ▁bis ( tri phen yl ph osph ine ) imin ium , ▁(( C 6 H 5 ) 3 P ) 2 N + ▁t ert i ary