(E)-5-(2-Chloro-phen-yl)-7-ethyl-2-oxo-2,3-dihydro-1H-thieno[2,3-e][1,4]diazepin-4-ium 2,4,6-trinitro-phenolate.

In the title molecular salt, C(15)H(14)ClN(2)OS(+)·C(6)H(2)N(3)O(7) (-), protonation occurred on the double-bonded N atom. One of the nitro groups shows slight disorder over two orientations, with an occupancy ratio of 0.91:0.09. In the crystal, classical N-H⋯O hydrogen bonds, as well as C-H⋯O contacts connect the components into a three-dimensional network. The seven-membered ring adopts a boat-like conformation. The least-squares plane defined by its non-H atoms encloses an angle of 38.99 (6)° with the benzene ring bonded to it.