The cyclic pentazolium cation (N+ 5) is not known due to its probable antiaromatic character; whereas the open-chained pentazenium cation (N+ 5) is known.
Kation pentazolium siklik (N+5) tidak diketahui karena kemungkinan sifat antiaromatiknya; sedangkan kation pentazenium yang berantai terbuka (N+5) diketahui.