organic compounds
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In the title salt, C13H19N2+·BF4−, an ionic liquid, the butyl and ethyl substituents bonded to the N atoms of the imidazole ring [r.m.s. deviation = 0.019 (1) Å] adopt equatorial positions. The crystal structure exhibits slipped π–π interactions between the imidazole and benzene rings of neighbouring molecules [centroid–centroid distance = 3.529 (2) Å]. In the tetrafluoroborate anion, the B and F atoms are disordered over two sets of sites with site-occupancy factors of 0.813 (7) and 0.187 (7).