Like NaCN the most stable geometry of KCN is cyclic, although there are linear KCN and KNC minima as well (as for NaCN). KCN is an ionic compound, as the density cross-section shown here demonstrates very clearly. KCN is one of the many cyanide species detected to date in space. As a salt, potassium cyanide is a well-known and infamous poison, both in real life and in fiction.