Ethidium hepta-fluoro-butyrate.

In the title compound (systematic name: 3,8-diamino-5-ethyl-6-phenylphenanthridin-5-ium 2,2,3,3,4,4,4-heptafluorobutyrate), C(21)H(20)N(3) (+)·C(4)F(7)O(2) (-), two ethidium ions, C(21)H(20)N(3) (+) form a dimerized structure due to π-π inter-actions, even though they are positively charged. The hepta-fluoro-butyrate anions are connected to neighbouring cation dimers via hydrogen-bonding inter-actions, the hydrogen-bonding donor sites of the -NH(2) groups of the ethidium ions connecting to the hydrogen-bonding acceptor sites of the -COO(-) groups of the hepta-fluoro-butyrate anions.