The first direct observation of the tautomeric equilibrium between mesoionic imidazolium aminides (IA) and amino NHCs (AC) shows its dependence on the aminide substituent. A potassium (imidazol-2-ylidenyl)(anilide), an ion-pair with the ‘free’ anionic NHC, and potassium organometallic polymers, with the repeat unit exhibiting ‘Janus-type’ coordination, are reported.