A zwitterionic cyclopentadienyl annulated imidazolium salt

The first directly annulated cyclopentadienyl–imidazolium salt has been synthesized and fully characterized. In the solid-state, this zwitterion arranges itself in a hydrogen-bridged head to tail trimer which optimizes ionic interactions. Substantial π–π interactions are absent. The UV spectrum of the imidazolium innersalt reflects the intimate electronic interaction arising from direct fusion of cationic and anionic fragments of the molecule.